Human Social and Biology ® for CSEC Richard Fosbery INCLUDES Peter Givens Pamela Mark CD Hunte Morris Angela Ramjit-Delochan 0 C 0 V') 835292 HSB for CSEC 2e Edition cover.indd 3 <l) z 14/01/2015 t r aP 2nd fo --.J dr o f x O ...c I- ytisrevinU C 1.... s serP V') <l) 14:26 Unlimited/Corbis; 3 Photo p155: Great Clarendon Oxford It Street, University furthers the Oxford, Press is a University’s OX2 6DP, department objective of United of the p139(B): Wheeler/Science Keith Library; p116(B): Jiri by publishing worldwide. 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Images; LIBRARY Quallo; p283(B): Richard Visuals Gladden Willis/Visuals We are grateful reprint Fosbery an in Although before for extract Cambridge we have publication publisher permission from will ‘The Cambridge International made this rectify to history every has any effort not been errors or of AS to University vaccination & A Level trace and against Biology contact possible in every omissions at the Press for smallpox’ (CUP, all case. earliest permission by 2013). copyright If to Richard notied, holders the opportunity. 13/01/2015 15:36 Contents Introduction 1 B.4 The B.4.1 UNIT skeletal Bones Cells, tissues, whole A .1.1 organ systems, organisms 2 Characteristics of B.5 A .1.2 Animal and A .1.3 Microbes Specialised Movement into plant cells Matter Movement and out of cells energy across 19 webs flow 32 and A .4.1 Energy A .4.2 Carbon B.1 chains food 32 Interdependence Energy of organisms cycles t hrough and an 39 ecosystem nitrogen cycles Nutrition Balanced B.1.2 Teet h diet B.1.3 Enzymes Digestive B.1.5 Absor ption digested 45 B.7 49 Homeostasis B.5.2 The 175 B.5.3 Kidneys B.5.4 Homeostasis 187 B.5.5 Skin 194 functions of t he kidney 179 and healt h 183 Coordination and control 207 B.6.1 The B.6.2 Ner ves, ner vous B.6.3 How B.6.4 The B.6.5 Types B.6.6 The B.6.7 Eye system neurones 207 neurones endocrine of and send reflexes impulses system 210 216 219 receptor 225 eye 229 236 defects Reproduction 243 B.7.1 The reproductive B.7.2 Egg and B.7.3 The menstr ual B.7.4 Fer tilisation B.7.5 Pregnancy sperm systems 243 production 247 cycle 252 and implantation respiratory and t he fate of 255 Bir t h B.7.7 Family UNIT and (gas overeating of t he Meiosis 284 C.4 Variation 289 97 C.5 Monohybrid 103 C.6 Genetic Smoking 108 B.2.4 Cell 1 12 UNIT D.1 The B.3.4 Hear t of system and inheritance engineering Disease and its impact on D.1 Healt h and humans disease 312 D.2 Non-communicable 312 123 function 131 system diseases 316 138 D.3 disease 302 D (non-infectious) circulator y 295 123 blood str ucture 278 C.3 B.2.3 and genes 280 breat hing respiration 278 Mitosis The mechanism variation Chromosomes breat hing system and C.2 B.2.2 exchange role 269 C.1 gas circulatory planning C Heredity exchange) and B.3.3 257 263 85 str ucture Hear t of 80 The B.3.2 role placenta B.7.6 97 The t he 76 products Undereating B.3.1 and 70 system system The 175 Excretion 58 C.1 B.3 165 67 B.1.4 B.2.1 158 B.5.1 t he The joints muscle 58 B.1.1 B.2 and skeletal 45 B B.1.6 of surface Photosynt hesis A .3.2 car tilage 21 Photosynthesis, food Function 19 cell membranes and Bones, B.4.3 12 B.6 A .3.1 B.4.2 154 4 cells and A .2.2 UNIT and 8 A .2.1 A.4 skeleton 2 A .1.4 A.3 t he uses living organisms A.2 of 154 A t heir A.1 system Communicable (infectious) 145 diseases 322 iii 835292 CSEC HSB TOC.indd 3 08/01/2015 15:54 Contents D.4 Effect of vectors on UNIT human healt h 325 E.1 D.5 E Met hods of Impact the microbial D.6 The against D.7 Use growt h body ’s health practices on environment 353 331 E.1 Pollutants E.2 Water – its cycling and treatment and t heir effects 363 353 E.3 Sewage 368 E.4 Refuse 372 defence disease and of controlling misuse 337 of dr ugs 344 Index disposal 380 iv 835292 CSEC HSB TOC.indd 4 08/01/2015 15:54 Introduction Human and Social Biology for CSEC® is a comprehensive course Practical designed to help you has written achieve your best in t he examination. Practical been by experienced teachers who have work to make it easier for you to master t he key t he subject time is you ot her sciences place in and a science are as nature it our natural which you learn you will t he should t his on discuss issues, t he responsibilities and So issues to many scientifically t his is not like all of ourselves, to each have is a principles and apply wit h human do not subject our in t hem. healt h have are ot her just t hese your t he biology not do of But we t his scientific and t hink course. environment. facts also environmental you on concentrates and to Here and working to do These answers. So your opinion is ver y important number activities practical designed skills to since they some hazards. is be require These tell finished you each so it important to describe. what you should Look at be able section ‘ Yes, I If can not, Key we in t hat’ over to do once carefully you before has have a are have ready topics in finished. to t he move section If you onto can To We that them Some have we vocabular y. of in the also think you bold most made you Studying learn a the type t he again next and where complete to Biology important important need they are in section. find It is a is like words are own are not for a terms, defined called you good learning of idea glossar y as well where you the terms. You will find the These suggestions are These can add notes about glossar y on the connections between Did know? help you different learn, par ts of revise t he We hope They t hese might t hem wit h your tip Ever yone who you exams. prepare you teacher to and facts go t hat and your the T alk how have course. you course. has for to contributed have t he apply to Written t hat will based procedures and on involve practical that you work may have boxes find and highlight The equipment list any you of potential hazards requirements in need in order to includes a work any safely . activities special t hat you apparatus. can do at However, home you as t hey should always case studies developing analysis are included your and t hroughout t hinking skills evaluation of t he t hrough book. t he information and data. have written family some and talking teacher. points They for are an you to discuss important with part of your this because syllabus you by hearing can learn talking their to much others about and many gaining of the ideas topics from in them opinions. make might your activity . Questions not own know. and share use the is good a the friends. are look not exam-style carefully at information idea questions to to write and questions. what you answer out saying the to They have are learnt fairly each rather ‘Yes, I than can do to section straightfor ward answers yourself questions in help and questions. just that looking It at one’. put to some t his ideas book and knows somet hing suggestions to help At the about exams. end points. of You each can everything. be able Unit use to this there is like checklist When think a you of a short read the each summary to make point information in you of the sure the have main you have summary just read you read. skills is t he ver y skills all you impor tant calculate, Practise are materials is CD. t he have to estimate exercises and we learnt in ever yone predict give Mat hs and we to give t hroughout t he We give you questions based oppor tunities to on write information answers have at included questions Paper you. activities str uctured exam-style questions t his will in These the 2 activities supervision Summary We Mat hs plenty and Paper These under to syllabus. you of for Practice You apparatus in learning. about should Maths the develop make you interesting stimulate Exam about are your laboratory you studies are These you any inter pretation, and to a help to safely. book, skills in experience safety practical number the Study enhance out question to designed yourself need friends, use been key all to A We your this These do t he and first boxes glossar y know. are study work help you answer Case huge printed text. terms. terms you t he you and throughout have you information. language. the when course or terms Biology new do look relevant and the activities impor tant. Try each to special special t hem of and right outcomes section. part practical have and practical Learning of carried One The wrong an a concepts. course. This is included expected features activities It 1. (MCQs) We Paper 2. also Here you may have The answers in these that have we are be like have that questions that found on some those questions questions can sections test the you are on multiple will have similar specific topics from to choice in your the topics; questions in different the exam Units. CD. provided lengt h. CD This contents book extra includes practice and an interactive interesting CD to provide you with some activities. 1 835292 CSEC HSB Introduction.indd 1 08/01/2015 15:51 Unit A Cells, A.1 Learning By the should ● list of ● end be the of ● write topic you to: characteristics how Characteristics There seven are humans show characteristics definitions of Scientists seven study Those characteristics, e.g. at hletes help t hem have a who of life living systems, – organisms growt h, excretion organisms nutrition, and study human biology nutritionist advises people to t he who best advise of t hem t heir respiration, reproduction. t hese study trainers perform of movement, different characteristics. and the characteristics (sensitivity), who organ organisms A.1.1 irritability organisms describe these this seven living whole outcomes able tissues, are different also about about interested what t heir t hey exercise in t hese should eat routines to ability. characteristics. ● Growth is – is such as usually lost. as removing About cells Nutr ition sur vive. The by also make eating Figure A.1.1.1 World and Usain using a size absorbed to of an of use nd and an t heir increase, Dr y Size measurements, body decrease water organism. organism. linear t hen some per manent mass an animal two is weighing single cell. cells. water, t hem. This cell Anot her food . energy gives new t hey mass. again. which t hey Some This have growt h is mass measured is usually is t hen dened af ter so it is easy Organisms absorbs aspect food, of to calculate composed of increases growt h is an t he dr y many in size increase and in an a so supply t hat organisms: eating All organisms organism dies. need energy Animals in obt ain order to energy eat. t hem cells ot her is of t hey t he can herbivores biological grow. eat molecules Animals plants; t hat obtain carnivores t hey t heir gain food t heir animals. different. the dioxide into Plants gain their energy by absorbing light plants all the release Respiration water biological The waste into the – many This absorb biological t he and is is people breat hing. but chemical and reactions into molecules product air to be of photosynthesis sugars. of The that sugars plants are need photosynthesis used by other that then for is growth oxygen, organisms in respiration. of ten compared does not broken not Respiration enjoying drive functions. other cells Students to and their ● it carbon conver ted which A.1.1.2 of t hat nutrition conver t Figure people in size Bolt and p a t he Olympic Plant champion, by not obt aining ot her nutrition have in usually cells. is food food to – We weigh increase af ter into of increase ways. water. Wit hout t he need p from number is dr y cent animals divides from in t he per also to t hey t hat all grow t hen t he 70 of We because increase mass different appear Because an per manent in height. organisms ● a measured release in t he t hat you in so a your fuel much cells of respiration have chemical burning quite in t hink Af ter molecules down wit h occurs so. eaten food. like oil living or all is to do of It wit h you t his release gas. at to meal, Some reactions energy all a is a digest and travels energy. similar to your This is process once. organisms – wit hout energy lunch organisms even would when you be are dead. Energy is needed by t he body all t he time, asleep. 2 835292 CSEC HSB Unit A Topic 1.indd 2 08/01/2015 15:56 Cells, tissues, Aerobic respiration happens muscle in what it stimulus. to a The means These way react we in our to makes cold, ver y temperature t he Movement as – all no a supply oxygen bursts efcient of Movement might t heir is y trap t he context. or to is into may a Any put t he at of of oxygen. available, strenuous releasing 0 which ✔ activity. energy bad-tempered, change are in our detected or in on by jacket do insects, a is for We but Exam Think t han t hat body and is a lead to t he t hey to not irritability is is par t toxic of carbon if it t he chemical seven and two photographs identify This will and their to nd see how happening many in help you in this the learn section. the terms denitions. beach but bean in and The change putting on in t he sensitivity. some extent. t heir or to When position, avoid t hink pod plant, is changes body. food move, to cracks folds being about its t he open leaves to if eaten. way a release you its touch dioxide (CO ) is a waste product of Figure builds up body’s the reactions inside t he body, metabolism. t hat take This place in so is an must t he be term removed. t hat organism. A.1.1.3 move A and if Venus fly the touches fly trap – one one of respiration. 2 It these can false – tip you p Excretion organisms conditioning warm. change whole sensitive keep air stimulus of ten t heir t he t hem. ● about living is surroundings t he respond where movement animals, a a term move Mimosa, response. building building show plants catches a a stimulus, body t hat way being stimuli, Anot her essential t hink and suggests organisms move par t – go enter response. respond seeds sudden more stimulus you you you organisms Venus have is characteristics t his a When You cells t here of behaviour. temperature. is much changes, in jacket during (sensitivity) change it if Characteristics respiration. Irritability not is organisms when occurs cells respiration whole occurs respiration anaerobic ● systems, Anaerobic Aerobic ● organ hairs the trap will snap shut Respiration covers Excretion sensitive all is t he 0 t he Key terms ! removal During Any of t he t he waste day, carbon products plants dioxide use t hat of metabolism. photosynt hesis t hey produce is to produce used in t heir t heir own Respiration The breakdown nutrients photosynt hesis do not excrete it. Instead, t hey have more oxygen t han t hey release it is lost from t he also requirements. substances includes In and our we Reproduction – removing case, excrete one respiration water t hem substances and in salts are t hat are good sur plus examples in to of t hese occurs Anaerobic Respiration urine. of t he inevitabilities of life is deat h. For life is Respiration reproduction is oxygen is present respiration that not occurs present in when cells. to Stimulus continue, when cells. oxygen ● cells body. that Excretion inside energy. need Aerobic and of so to t hey chemical food. A change in the essential. environment. In asexual growt h. t hey reproduction, They grow to eit her organisms divide produce par t into of two t he reproduce (as body happens t hat by using wit h breaks a form bacteria) away to of or form a Metabolism reproduction individuals without toget her at involves fer tilisation. t he production of sex cells t hat occur chemical Asexual new reproduction the that in an organism. new individual. Sexual All reactions fusion from of one Forming parent gametes. fuse Sexual new reproduction individuals gametes by (sperm Forming fusion and of eggs). 3 835292 CSEC HSB Unit A Topic 1.indd 3 08/01/2015 15:56 Animal and plant Cells, cells q 0 Study ✔ You will read molecules A.1.1.1 Definitions Unit about B.5. biological Do not Characteristic Denition the Growth A information about permanent plants rely Obtaining on plants for our food oxygen. W ithout them not examples them later be life here. Look of how we in this unit out in size, dry mass and the number of cells food for to provide energy and biological molecules; plants need light photosynthesis The chemical and reactions make it in cells available that for breakdown cell food substances to release activities for depend and increase we energy would of organisms and Respiration our characteristics whole – energy we the systems, skip Nutrition over of organ tip more in T able tissues, on Unit Irritability The B.1. ability respond Movement Excretion by to The change The removal substances Reproduction The living organisms to detect changes in their environment and to them in position of in formation waste of the body products of excess of of individuals new or part of the metabolism, body toxic substances and any requirements to become the next generation Questions 1 Explain at p Figure A.1.1.4 a seahorse male been incubating young now inside time for seahorses a to the should end be eggs line he and pouch, next make the birth; gives the brood the Learning By Continuing this able describe How 3 Explain 4 What and it you structure and structures the animal ● state and the plant plant and carbon dioxide does the how do nutrition sexual animals of plants differ reproduction gain from their from differs the from nutrition asexual of animals? reproduction. food? is A.1.2 All Animal organisms can animal day appearance topic list the of easily be are seen photographs and made using taken of a plant smaller light wit h a cells units called microscope. light cells. Figures microscope of Animal A.1.2.1a typical and and plant plant cells A.1.2.2a and animal of cells, ● during has to: the oxygen night. 2 are ● excrete – outcomes of plants the generation an why toget her wit h diagrams illustrating t he visible str uctures. cells within cells function of each nucleus of ● these make a structures table to show vesicle the (small similarities between plant and vacuole) differences animal mitochondrion and cells. cell surface membrane cytoplasm 0 Key term ! p A.1.2.1a through Cell The structural organisms. by Figure cell All cells surface contain unit are of a light Cheek cells microscope viewed p Figure A.1.2.1b typical animal The structure of a cell most surrounded membranes and cytoplasm. 4 835292 CSEC HSB Unit A Topic 1.indd 4 08/01/2015 15:56 Cells, tissues, organ systems, whole organisms Animal and plant cells mitochondrion cellulose wall: cell maintains shape of cell nucleus vacuole contains watery sap chloroplast: of site photosynthesis cytoplasm cell surface membrane p Figure A.1.2.2a through a light Leaf Animal and Plant animal have and a cells viewed p Figure microscope plant jelly-like cells a cells share cytoplasm leaf A.1.2.2b The structure of cell structure many common surrounded by a str uctural cell features. surface Bot h membrane 0 t hat Key terms ! separates cell t he cell from its surroundings. Inside t he cytoplasm are some str uctures. Cytoplasm where The most obvious of t hese str uctures are t he green chloroplasts which most only in plant cells. Chloroplasts contain t he pigment are t he str uctures t hat carr y out photosynt hesis. Chlorophyll energy making it available to special molecules wit hin occur. t he conver t water and carbon dioxide into sugars and Just visible, in bot h animal plant not have a easy to chloroplasts. They are wit h a see like good light Mitochondria cells to Also, carr y just microscope are out visible do and These t he t heir in site called vesicles A of inside feature are long Each t he by t he strands strand controls of one Plant This Plant sap cells is and have outside cells have subst ances for on wall cell pressure of a a is of They t he genes cell cell. t he are in The inside t he cells, wit h and t hey Each much so is t he and are are are special release small, around This light, a growing are instr uctions is microscope Mitochondria contain sections. more the of cells; cytoplasm by envelope. visible energy structures Gene that Short controls a Thread-like are made length feature of of of DNA an DNA. that organism. for dividing. spherical cell. separated from r unning section nuclear Chromosome not dye. chromosomes, for from is a t he cells. gene information t he which t hat about C.1. in cells is are made vacuole solution. outward to t hey and per manent suppor t light stained moving, Nuclei because sugar s are nucleus. There Unit shape as a chromosomes activities oxygen. absorbing smaller. plant t he into cell. for substances membrane and gives such envelope. divided large, t he is wit h respiration and carr y cells DNA. salts water of xed t he cont aining t he of feature chromosomes t hat also cells aerobic animal nuclear DNA t he functions bot h vacuoles cytoplasm of if cells, pigment the chloroplast the mitochondria. Contains controls separated t hat material chemical absorbs and light cell’ s chlorophyll Nucleus and jelly-like a are reactions found A of t he sur rounded of whic h The pressure of cell The maint ains is of lled vacuole cell. and layer s t he t heir a cell wit h stores water wall by cellulose in a bres. water y t hese t he vacuole wit hst ands shapes. wall. t he Looking 5 835292 CSEC HSB Unit A Topic 1.indd 5 08/01/2015 15:56 Animal and plant Cells, cells at Figure boxes, A.1.2.2b but t his c hloroplasts. lower layer is you not The of upper cells t hat Practical Observing It is easy them 1 2 dropping Use a cotton this Transfer the coverslip any 4 mounted needle 5 them pipette so or the shown around to flat, in the the disinfectant. of are are long, a dropping pipette coverslip and to use a in cells two are whole like layer s of cylindr ical organisms long cells cells t hin wit h and t he shape. lining of your cheek, stain of water on object to scrape a the microscope inside of slide. the cheek. removed. of cheek the a piece into Use a the water piece of and paper add a towel to absorb coverslip. that add a inside microscope. drop your object the the light diagram. edge place Use put from the from a blunt Immediately of of spher ical cells with a solution plant all t here consists near cells scrapings as water are some at bud firmly layer t hat leaves systems, Activity off look a t hink Inside organ cells scrape then Use Do 3 human to and might so. tissues, you little of used to scrape methylene paper towel blue to your stain absorb cheek into to edge one some water coverslip from under coverslip 6 Put some paper the and coverslip the more towel to cells water on will at remove the opposite absorb the any side stain some of the not side. of The stain will go under the it. coverslip absorbed and by absorb the it with the cells. slide 7 Look at the slide with low and high power of a microscope. water The p Figure cells should look like those in Figure A.1.2.1a. A.1.2.3 Written Use all animal the and Activity information plant cells. in topic Set Feature Cell Animal next to make table like yourself a table of the table, table you is will cell completed nd that Plant for you compare cell ü you. can to this: û row your If add you more leave rows space after at the reading end the page. Making you A.1.2 your wall One of out tables need these to to like learn. help this This learning is a very book and good way contains to more organise many opportunities to of the topics that make tables like revision. 6 835292 CSEC HSB Unit A Topic 1.indd 6 08/01/2015 15:56 Cells, tissues, Looking Light are To see things more between Figure If the you extra much extra tiny to us a tantalising cells scientists than animal light. that use we electron The beams objects inter pretative the than is Animal see into the with electrons possible diagram a type that help with in world this microscopes of and plant cells cells glimpse cannot smaller use to light Figure of of cells. There microscope. beams of distinguish microscope. A.1.2.4b show some detail. Figures detail be give at organisms and compare cytoplasm are detail whole closely inside rather A.1.2.4a cell systems, more microscopes many electrons, of organ is no seen described t hat longer wit h in A.1.2.4a an an t he Table and electron empty light b wit h Figure microscope area, but microscope. is is full The A.1.2.1b able of to you show. str uctures functions of will Notice t hat t hese see t he t hat are t he too str uctures A.1.2.1. nucleus rough endoplasmic reticulum nuclear mitochondrion envelope nucleus Golgi apparatus cell surface membrane cytoplasm mitochondrion rough u Figure A.1.2.4a Part a cell of – was q Cell image made T able Cell human this electron with ribosomes an microscope A.1.2.1 The functions p of structure surface cell structures reticulum Controls Many (Golgi body) Lysosome Nuclear (plural: mitochondria) envelope to it is All the chemical Nucleus Contains Ribosome Very the the The structure of the cell shown in Figure A.1.2.4a of from and and by aerobic the that the cell transport endoplasmic cells which respiration cytoplasm; substances around the cell; if there are ribosomes reticulum endoplasmic destroy the leave canals rough can reactions nucleus and as produced that nucleus enter reticulum are eaten occur small for by within pores export the this (holes) in cell out of and the any cell worn out cell structures such structure the nucleus allow substances to pass cytoplasm ribosomes DNA small Small tubes known substances mitochondria Produces vacuoles) it, chemicals Separates Nucleolus (small A.1.2.4b cells substances as between Vesicles which Packages Contains Mitochondrion animal interconnected attached apparatus in Figure Function membrane Endoplasmic Golgi endoplasmic reticulum that spherical membrane makes structures to that structures be up the make that chromosomes proteins carry from which amino substances control the cell’ s activities acids packaged by the Golgi apparatus to the cell surface exported 7 835292 CSEC HSB Unit A Topic 1.indd 7 08/01/2015 15:56 Cells, Microbes 0 ------, Study ✔ Most cells organ systems, whole organisms Questions tip are less than 1 mm 1 Refer to Micrometres (µm) are Figures A.1.2.1b and A.1.2.2b and list three ways in which an in and animal size. tissues, the a plant cell are a similar to each other , and b different from one units another . used to measure 1000 µm in them. 1 mm. some maths soon, so There There questions remember will are 2 be coming a up What the name cell and 3 List 4 the What a 5 cell Look 6 the end be of this able topic you State Bacteria, to: not state that bacteria, viruses the structure b that Which of forms the the cell boundary structures between shown in are cell at is in are involved in making, processing and cells. cell wall c structures A.1.2.4a. of cell. the necessary for? mitochondria Figure cytoplasm it membranes? that following b of to add a d Name stain vesicle the cell the epithelial to structure that cells fills from most the cheek. Microbes vir uses and organisms and fungi fungi like break are the all microbes others down we dead or have and microorganisms. considered. decaying Many Vir uses species material, and these fungi used are of are fungi called and the why living bacteria ● proteins carefully the A.1.3 outcomes are consist structures chloroplast of should to surroundings? its A.1.2.4b transporting By given this. Figure Learning is decomposers. Some species of bacteria and are in making microbes food such as yoghur t, bread, cheese and wine. We have made use of vir uses (microorganisms) in ● describe the structure genetic and ● 0 bacteria, fungi compare the the groups three and huge and Bacteria have bacteria are fungi numbers not cells. of reproduce individuals. survive suitable to give as they do not food source. reproduction is a light and cells t hose of life and the continuation C.6). Organisms pathogens. Many that infect pathogens other are organisms microbes. simple are cell and only str ucture some a few are t hat you can rod-shaped. micrometres in see in Many lengt h Figure exist and in can A.1.3.1. shor t only Some chains be seen one of electron are microscopes. surrounded plants, but by which cell ser ve walls, t he which same are not function of made of cellulose keeping t he nd shape and preventing it bursting. The cells of some bacterial species Remember surrounded by a slime capsule t hat provides protection against ot her characteristic organisms of a spherical Bacteria Bacterial are that Unit Many cell’s a (see called tip like do are Bacteria wit h Bacteria disease of microbes. of Exam ✔ cause viruses structures of engineering of that ensures and reduces t he chances of dr ying up. the organisms. chromosome (DNA) slimy capsule (protein) 0 ribosome Key terms ! cell Decomposer feeds on bodies and and An organism breaks down that wall flagellum dead cell surface membrane wastes. cytoplasm containing Pathogen causes An organism that granules disease. p Figure A.1.3.1 A cell of a bacterium 8 835292 CSEC HSB Unit A Topic 1.indd 8 08/01/2015 15:56 Cells, tissues, Bacteria have str ucture of take a or agella Bacteria good no are nucleus, for colony. Look 1 out colony the a – may large star ts size at ruler figure: loop of DNA animal in plant bacteria t he divide or air, in of just one cytoplasm. as t hey whip-like do The not have extensions uids. water twenty bacteria t he cells, have ot her ever y number from wit hin and water Microbes and in t he minutes, t hat you soil. so can it Under does see on not agar as cell. skills the carefully Use ver y organisms Some ever ywhere a Maths Finding a from t hrough bacteria have Each just differs moving found to whole mitochondria. conditions, long systems, bacteria chloroplasts called organ of Figure to bacteria A.1.3.2. measure measure measurement A Now the in the Notice length millimetres, that of it one not has of in a the line indicating bacteria centimetres. 1.0 shown Let’s call µm. in this p 2 measure length of the scale bar in millimetres. This is Figure which 3 Divide the length of the bacterium by the length of the scale A.1.3.2 bar line in cause 4 Multiply = A /B Open the Bacteria into to feed simple be 1.0 CD as have a answer by check into cold protective suitable by the your making molecules, heat, length that the scale bar t he and enz ymes as cells. so can spores t heir food molecules which produce t hey t he digest These Bacteria, drought, return, t hat sugars. can spores sur vive sur vive wit hin for germinate and are a harsh t heir long and break small visible eye. fungi. Each not Fungi spore from t he in cell carr y as fungi has in out reproduce lands it. on This fungus. Figure t he under Most cellulose cannot shows t he a light are by and They making grows can to a do cell not see an a spores source into t hat grow a Many are alt hough wall have hypha is t hat t hin it down conditions cells. time. divide also yeasts which is These When again. visible are made chlorophyll, t he are of spores surface. network, enzymes t hen which is car r ied t hread, network release food a many over extensive hyphae of microscope. multicellular, nucleus plants. digested tip a suitable for m The The bar a or to t he of A.1.3.3 got out left mouldy; single-celled out Figure fungus in This the different have piece air and types grown all of bread has gone of mould over it chitin, chloroplasts, so photosynt hesis. soon You to mycelium. fungus. a A.1.3.4 bread µm scale called enough p naked 1 of r answer. such covering conditions are is the length represents: Fungi Fungi the µm. to absorbed such bacteria poisoning; (A /B). your × food indicating (micrometre) millimetres Salmonella B t hreads have The where it to as is t he on t he t he also t he If t he hypha, of bread into body food hyphae. grows body grow fungal digest t he wind. a for m landed which by t he hyphae which absorbed by known or outside Figure t he A.1.3.5 grows. p Figure mould A.1.3.4 fungi through a This from light structures to released this fungus to what bread microscope; black be is the are into full the another of air one of looks the little spores to food the like about spread source 9 835292 CSEC HSB Unit A Topic 1.indd 9 08/01/2015 15:56 Cells, Microbes tissues, organ systems, whole organisms ' 0 Key terms ! Enzyme made of Spore A biological catalyst protein. A very small reproductive structure. Hyphae form The the The thin threads mycelium hyphae structural have of the features as a that fungus. same endoplasmic cells. vacuole nucleus reticulum Mycelium that grows Parasite The from Any body one of a fungus spore. organism • that 0 0 0 t gains on its nutrition another known as by living organism, the in which Figure or of is a body o ~o host. is A.1.3.5 mould is the enlarged structures same cell mitochondrion ribosomes wall cell fungi water for feed temperature. on, or on growt h, in, dead or oxygen Some anot her fungi living decaying for are structure the mycelium; so you inside; the cell fungal a can hypha see these are structures the the in membrane cells Most as The fungus; aerobic matter and respiration parasites, gaining to of do and a t heir animals t his and t hey suitable plants need warm nutrition from living organism. Viruses Vir uses are t hat are million 1 electron Vir uses or t he causes are is t he and RNA. Vir uses If impression of virus of looks This what like is an one (×260 you far is in They composed maybe enter Vir uses To do enter producing A.1.3.6 cells. compound t hat multiply. Figure not material or nanometres similar coat small; inuenza smaller t han approximately a millimetre). bacteria 120 and fungi, nanometres Vir uses are only in e.g. size visible t he (t here under an microscope. parasites p extremely vir us host new breat he a ot her t he do t his of cells few par ticles genes of and t hat t hat anot her respire must made surrounded proteins cells not t hey are RNA) and make take code help t hem a of for it of over t he cell and material coat. (t he All host) t heir own str uctures turn The proteins, reproduce. make t he genetic protein organism cannot use up by t hem (DNA genetic which vir uses in order t heir into are to protein, of form DNA hosts. factories vir uses. in t he vir uses t hat cause measles or inuenza, t hey enter artist’s particular 000) type t he cells of your vir uses t hat Vir uses can do not ver y and t hroat. more be harmful ver y respond constantly nose invade to of your because antibiotics. change into new Here cells Some strains, t hey to t hey of reproduce make can t hem, making even to reproduce such our make more as t he effor ts lots of new vir uses. ver y quickly inuenza to control and vir us, t hem difcult. 10 835292 CSEC HSB Unit A Topic 1.indd 10 08/01/2015 15:56 Cells, tissues, organ systems, whole organisms Microbes surface proteins genetic material protein coat HIV adenovirus – respiratory infections p rabies Figure A.1.3.8 human virus Structure of a virus o ___ Study ✔ You can read microbes E. ebola influenza virus in Section microbes and cause microbes Figure are A.1.3.7 some diseases Viruses examples they of come in viruses different that infect shapes and us the and sizes; names ahead here of D deals about are that in now are with see of the and those The useful Section to D harmful diseases. photographs the more Sections that described p tip E. to us roles to us of are Look some them. cause Questions ✔ 1 Make a table to show the similarities and differences between Study the Answer structure of bacteria, fungi and facts help Cell Bacteria wall Explain 3 Calculate (Use 4 why the the things that in Human the page do not to help organise virus 9 to learn and them. û without shown help decay. to microbes being in inside Figure a host cell. A.1.3.6. you.) Suggest why microbes did not bodies are a 1000 years old and were found in frozen Siberia. bogs Ancient on of 1 these following: ground into width reproduce you about Viruses ü cannot activity dead Mammoths peat c actual maths Sometimes b viruses the decompose a Fungi ü 2 question viruses. the Feature tip in that Egyptian burial are over 2000 years old and were found in acid Denmark. mummies that were dried out before being placed chambers. 11 835292 CSEC HSB Unit A Topic 1.indd 11 08/01/2015 15:56 Specialised Learning By the Cells, cells end A.1.4 outcomes of this topic be able identify some of including epithelial, sperm cells egg functions. ● state importance specialised that similar into are cells identify organs into organs some and specialised A.1.4.1 – function one work are specialised together to to make carr y the out whole Muscle cells, ner ve each have cells and epithelial cells their cells. shapes They are different a cell from membrane, each other nucleus (Figures A.1.4.5). This and gives rely them on great others to advantages meet their as cells can concentrate requirements. For example, are cells need to be supplied with glucose and oxygen, cells in the gut oxygen digesting from the food lungs to provide and glucose, transpor t it to and red muscles. blood Red cells blood take cells are are organ human organ in into around the body by the muscles in the hear t, which contract to push systems the ● efciently. but on moved organised which cells tissues, organised and cells, of up organs have specialised cells specialise tissues of cytoplasm, muscle organised function examples and the organisms These and are having cells muscle, nerve, describe organisms cell many-celled organism ● whole specialised cer tain cells systems, to: Most ● organ you Types should Specialised tissues, blood through our blood vessels. tissues, systems. nucleus muscle, e.g. cytoplasm biceps contractile fibrous with proteins tissue p Figure A.1.4.1 tapered at form a food through move strong eggs oviducts the end tissue the from and sperm Smooth either muscle so they that canal ovaries sperm from to to move and through the are together contracts alimentary the cells fit testes the along ducts cytoplasm tendon (attaches muscle to full of contractile bone) proteins nucleus bundle of muscle fibres cross link: helps with the coordination the single light muscle of beat fibre band p dark heart Figure A.1.4.2 only the Cardiac muscle cells, found band in heart, joined together linked together are into short fibres; cylindrical these cells fibres are nuclei t Figure many partially permeable but A.1.4.3 muscle has many Skeletal fibres; muscle each nuclei. fibre Fibres cells is are are composed equivalent bundled to a of cell, together to membrane form muscles like the biceps 12 835292 CSEC HSB Unit A Topic 1.indd 12 08/01/2015 15:56 Cells, tissues, Much of in arm, t he our organ body are systems, is made organs as whole up of t hey organisms skeletal are Specialised muscle. composed of Muscles, different like t he tissues, biceps such 0 as Key cells terms ! skeletal muscle tissue, blood and tissues that brous tissue. Epithelium Epithelial cells form line body cavities. Imagine a journey body through your nose and into the depths of your lungs. The air ways are lined by special, protective cells which are shown in into Figure of the cells that make you have a sticky substance breathed in, such that as traps fungal any small spores, form and saw dust. them These cells thought are they called looked goblet like cells goblets, because which the are of the cells in this epithelium are cells with many scientists drinking cilia. One of the cells epithelium. A group perform These the of similar same cells function. who A group of tissues that cups. work Most cell an vir uses, Organ rst a foreign bacteria, that pollen lines A.1.4.4. Tissue par ticles that your that Some tissue cavity. Epithelial lungs A down together to perform specic A of tiny functions. projections move from side to side in a coordinated fashion to move mucus Organ up the air ways and into the back of the mouth. These two specialised that work together to protect the lungs against damage and work Ner ve cells of are t he specialised body to for anot her t hin cells rat her cells t hat transmits like This tells muscles t he t he in wires contract transmission form in house. information to fast t he to a from of information pulses. Figure A.1.4.5 brain t he t he move of electrical food to along. They shows one alimentar y There is from are about ner ves in Unit much of t hese canal. (see and eggs Figures cells and This is A.1.4.6 t he diag rams – are sex and is t hat t heir in nuclei An and number will into wit h ever y anyt hing made ✔ more especially reproduction impor tant difference between – cannot so cells half t hat t he t hat do not generation. As a t hey fuse you number we unless for ner ve contain reproduction, c hromosome g row muscle organs out function for the one body. is Study a tip shame, but -i we cannot show B.6. (gametes) A.1.4.7). epit helial, impor tant not cells carry o ___ you Sper m group to one long, It information together infection. major par t system cells of toget her at t hese see in t he c hromosomes. double result, to in a and the book fro to airways YouTube show move to for how how the cilia mucus mouth. some cilia these video move along Look clips on that move. our sper m and eggs cilia fer tilisation. any move mucus trapped and particles mucus-secreting nucleus goblet Maths Finding Look 1 out the carefully Use a not in The egg size at ruler of Figure to human A.1.4.6. measure centimetres. the This is cells Notice width of that the it says egg the cell: magnication measure in is × 300. millimetres, A measurement p 2 of the cell egg is 300 divide times your smaller than measurement the by drawing. 300. Y our T o find answer the is actual size Figure that B A.1.4.4 lines goblet Y ou will see that your answer is much less than 1. It is always better in sizes in whole numbers so multiply B by 1000 to give an Part make cells of airways an in mucus move the epitheli um the lungs; and mucus to towards give the cells ciliated 3 cell skills the mouth answer micrometres. Open the CD to check your answer. nucleus Red blood body. cells They are have a specialised peculiar for shape t he transpor t of ten of described oxygen as a around biconcave t he disc. There \4 axon is no nucleus, which haemoglobin t hat oxygen blood when leaves plenty combine ows of loosely t hrough space wit h for millions oxygen tissues t hat in t he need it. of molecules lungs and Having no of release nucleus p also means t hat it is easy for red blood cells to change shape, which t hey Figure the as t hey t han a pass red along blood capillaries cell. – tiny blood vessels t hat are not much A.1.4.5 A nerve cell (neurone); do wider arrow impulses this shows than the are direction transmitted of the long cell 13 835292 CSEC HSB Unit A Topic 1.indd 13 08/01/2015 15:56 Specialised Cells, cells Table its A.1.4.1 shows you how t he tissues, str ucture organ of systems, each of t hese whole cells organisms is suited for function. jelly-like We have many more types of specialised cells in our bodies. It is estimated coating of egg t hat t here Sections cell q surface T able are B about and 200 of t hem. You will read about more of t hem in C. A.1.4.1 Specialised cells and their functions membrane T ype of cell Structure Muscle Cytoplasm Function is full of contractile Contracts to bring about Transmits an electrical movement proteins cytoplasm Neurone Long (nerve two cell) as follicle Figure A.1.4.6 A human cell; the ovary cells when it from is the it is ovum released surrounded ovary that brain The free epithelial cilia – between body, and the distance such from one impulse part of the over body a to long another gut that move is thin back Cytoplasm from by surface short, covered Cilia in move direction, processes mucus e.g. made along by goblet airways to cells the in one mouth forth and or nucleus has has stored energy; Female chromosomes keep follicle helped in gamete; the nucleus contains resulting contains stored zygote genes alive from energy after the to fertilisation; mother its Sperm development the the of Ciliated Egg egg process cell nucleus p thin parts Long thin cell with Male very gamete; release mitochondria energy for (×300) little cytoplasm; many has cell mitochondria; chromosomes; agellum swimming has and nucleus forth to to propel reproductive long from (‘tail’) the reach the the system; male to egg; the cell tail through nucleus egg lashes at back the delivers female genes fertilisation nucleus head mitochondrion Red blood cell No nucleus; cytoplasm lled Haemoglobin transports oxygen; without neck (spiral with shape) haemoglobin the cell can haemoglobin; not having a nucleus have a lots of nucleus middle means the cell to move can easily change shape piece Figures cell A.1.4.1 – A.1.4.5 show t hat help specialised through cells are capillaries attached to each surface ot her to form tissues. Figure A.1.4.9 shows t hat organs, such as t he membrane stomach, flagellum Organs p Figure cell A.1.4.7 A are composed of different tissues. (‘tail’) human of ten different sperm work levels of toget her in organ systems. Cells ● Tissue same ● Figure cells 0 A.1.4.8 Human red blood (× 2500) Organ one ● Exam – Organ – you write you should something that function. about t hese A e.g. collection e.g. system – A of similar muscle of t he cells tissue, different hear t tissue is and collection an Organ system 1 working ner vous tissues toget her tissue working or made of epit helial tissue (see different organs carr y toget her organ of to epit helial muscle Table and to out t he tissue. carr y tissue, out ner vous A.1.4.2). their structure up carr y of out t he one hear t major (an function, organ), blood e.g. t he tissues working vessels circulator y (organs) and system (see Table blood (a A.1.4.2). say structure helps table to specialised always about This collection connective made tissue) how shows tip is When A function, toget her cells char t J-.[ Organs Tissues function, tissue, ✔ ow (×2000) ,_______,,- ., _ _ _ _ _ _- . [ p The organisation: with should and their help. 14 835292 CSEC HSB Unit A Topic 1.indd 14 08/01/2015 15:56 Cells, tissues, organ systems, whole organisms Specialised AN FOUR ORGAN: the cells stomach TISSUES smooth muscle tissue -· AN ORGAN the digestive SYSTEM: system oesophagus epithelial tissue epithelial tissue surrounded by layers of tissue making wall of two smooth the muscle up liver the intestine stomach gall bladder pancreas duct duodenum secretory tissue in the pancreas colon (large intestine) ileum appendix rectum blood p Figure A.1.4.9 digestive q T able The organisation of specialised cells, tissues A.1.4.2 The main organs and organ systems of the spinal T estis and cord sperm Trachea, bronchi, Kidneys, ureter and and the ducts (male); ovary, oviducts and uterus (female) bronchioles Excretory vessels making stomach, thyroid Reproductive Respiratory bladder bones glands, systems Nervous and blood the Oesophagus, Adrenal in body Organ Brain, Heart organs human Organs Skull and system Circulatory up small gland, limbs and and large pancreas pelvic and intestines, pectoral pancreas, girdles liver Skeletal Digestive Endocrine 15 835292 CSEC HSB Unit A Topic 1.indd 15 08/01/2015 15:56 Specialised Cells, cells Some bot h t he organs t he hormone circulator y 0 may be digestive in more system insulin. t han and The t he liver tissues, one organ system, endocrine functions in systems, e.g. t he system t he whole pancreas because digestive, it organisms is in secretes excretor y and systems. Questions Did you know? ? Blood not is joined muscle are a tissue, together tissue. the as Instead suspended called but in a cells they are 1 Define the 2 What are 3 State two 4 List 5 How terms: tissue, organ and organ system are the advantages of having specialised cells? in the cells watery uid the specialised tissues that cells make that up are the not organised into tissues. stomach. plasma. do muscle cells rely on red blood cells and nerve cells? Summary Cells, ● tissues, There are seven respiration, ● ● Cells The are organs, of Cell units by Cell walls, found ● ● ● in The oxygen Cells are T o the T o for of function the aerobic the the image into by the printed calculate the length the answer on the of for as of less of an than have bodies nucleus and and animal permanent animal fungi the and nutrition, reproduction. made up cytoplasm, of cells. which are cells are mitochondria, e.g. and that red vacuole are features cells. viruses. help cells body. them is to that function. each cells in blood cells specialise of all the cells are the type The tissues object the in when length the scale image a growth, excretion in the organised is body structured rely in on each carrying body. into organs; organs systems. an length size the of and the large, tissues; organ size plant respiration into image have specialised requirements, organised organisms structures having organisms: ribosomes. bacteria, have of one their but are cells calculate length ● a in cells living movement, membrane. both not organised length in and out are surface are chloroplasts plant for Most animals and advantage carry life. reticulum Specialised other ● cell of (sensitivity), and that Microorganisms to ● a structures endoplasmic ● of plants surrounded ● systems characteristics irritability the cells organ of scale bar. a scale scale bar. Multiply bar, measure Divide your the answer the length by of the bar. object when millimetres 1.0 given the – given by multiply the by its magnification, magnification. 1000 to give an Do divide not answer leave in micrometres. 16 835292 CSEC HSB Unit A Topic 1.indd 16 08/01/2015 15:56 Cells, tissues, organ systems, whole organisms Practice 9 Practice Section 1 t he animal cell? following str uctures is not present in an 10 2 chloroplast vesicle Which of t he following are found in animal nucleus and B chlorophyll C cell cell Which and membrane 4 secretor y epit helium D ner vous Which is t he main A To allow function substances B To control to of pass t he in cell and membrane? out wall is and t he To digest large main function bacteria and transpor t oxygen. To transpor t carbon transpor t is A store of red blood main t he of cells. cell. substances. in chemical reactions. Which cell str ucture A nucleus is responsible for making protein? B cell C ribosome D cell membrane waste wall cells? Which cell A cell membranes str uctures B ribosomes C mitochondria D chloroplasts carr y out aerobic respiration? substances. dioxide. proteins. function of t he vacuole in a plant cell? 13 To store assist of vacuole To What To To activity chloroplasts C To C D t he mitochondria and B D B C cytoplasm 12 A impulses? cells? 11 3 transmits nucleus D D blood mitochondria C A A A of B tissue Questions Which A Which Questions Which is a group of cells t hat carries out a specialised substances. function? B To release C To produce D 5 To energy. control Which of t he A sugars B carbon A an B a system t he activity following of t he absorbs C a tissue D an cell. light energy in plants? Section 6 organism B dioxide C chlorophyll D proteins Which organ proteins. 1 substance is released from plants The diagram shows a typical human cell. during A photosynt hesis? A water B carbon C sunlight D oxygen B dioxide mitochondrion C 7 Muscle from cells place in to animals place. require Which energy process in for movement cells makes a energy State t he A respiration B locomotion C names diagram. of t he par ts labelled A, B and C in b State t he c Cells in [3] functions organs of such str uctures as t he A and kidneys and B [2] liver have sensitivity D many mitochondria. many mitochondria. Which of t he processes is responsible for t he removal why some cells have Explain metabolic waste substances in t he t he difference [3] between tissues and of organs. [3] body? e A Explain growt h d 8 t he available? Name two organ systems in t he body and state t he egesting main B defecation C respiration D excretion function of each. [4] 17 835292 CSEC HSB Unit A Topic 1.indd 17 08/01/2015 15:56 Practice 2 The Cells, Questions diagram human shows specialised cells from t he 3 body. a Describe b State cell A B C c is e 4 Describe b i) t he role Identify of t he cell cell A a Make b Use Describe t he type roles of shown t he in cells in i). The cells shown in C State one ii) Use t he provide protection system d Name a cell cells diagram function to type in shown to t he is in explain provide t hat for t he e Explain the typical vir uses labelled your which animal in a mould typical cell. cells a bacterial fungus. plant [3] cell [3] t hat are responsible [2] differ diagram diagram animal Humans to cells. have from of a explain t he cells of typical how plant plant cell. cells [6] differ [3] about body cell. human C 200 how different for and advantages ii) of 5 cells a Irritability i) [4] each coordination. having how t he types of specialised body are organised so t hat t hey cells of function t hat t he protection. responsible Explain [6] [1] of b [2] specialised cells. Use by t he ii) movement, in a body. following: i) ways of [4] of [2] organ t he str ucture cell. str ucture [3] efficiently. contains bacterial t he organisms you t he i) t he synt hesis. specialised c a which whole B. t hat c identified of systems, [2] from ii) a in str uctures how bacteria. a a t he protein Explain to t hree from Identify organ features ways similar Describe for four t hree differs d tissues, [3] t he following ii) iii) one t his State Explain i) is of human t he feature. one example of nutrition and respiration and of living irritability of each living growt h excretion and of explain between features reproduction to organisms. what is meant [4] differences pairs features examples in of plants. [1] t he organisms: [4] [4] movement. [2] 18 835292 CSEC HSB Unit A Topic 1.indd 18 08/01/2015 15:56 Unit A Movement A.2 A.2.1 Matter and of into and out cells energy Learning By the end outcomes of this topic you Matter should Matter is made from chemical elements and compounds. A is a substance t hat cannot be broken down into any Examples of elements t hat are in biological materials are describe oxygen, sulfur and phosphor us. In later units you the particle the three nature will matter carbon, ● nitrogen, to: simpler of substance. able chemical ● element be also describe states read of matter about t he impor tance of iron and calcium. Compounds are formed when ● elements on t he join Ear t h Matter is toget her are made water, of by forming carbon par ticles, chemical dioxide which can and be bonds. Common are made made made Ions of are of from one two or t he atoms element, more charged e.g. of or or nitrogen elements, atoms, one such groups of as atoms, more and that several forms. energy exists in cellulose. molecules or ions. Atoms are the smallest particles of a chemical element that can exist. Molecules par ticles explain compounds elements. oxygen carbon atoms, molecules. dioxide, which Some can Many proteins be are molecules eit her and are fat. positively + charged, The t hat e.g. sodium (Na is of universe matter movement energy of is made made requires of ) or negatively matter and par ticles energy energy. t hat called charged, are The such kinetic constantly kinetic as energ y chloride t heor y moving ). states about. (meaning (C l This literally ‘t he movement’). p Figure brain ions A.2.1.1 is Electrical dependent across on the membranes activity in the movement of nerve of cells solid liquid = particle gas p Figure A.2.1.2 matter. A have more solid more This kinetic kinetic diagram where they energy energy and shows are and the packed move move very behaviour tightly over and each of particles vibrate other, and a a in little, gas the a three liquid where states where they of they have much freely Matter can exist in three states: as a solid, as a liquid and as a gas. Look at Figure A.2.1.2 and think of a chemical substance such as water (H O). Water 2 is made of particles called water molecules which, in turn, are made of atoms of hydrogen and oxygen joined together by chemical bonds. When you drink a glass of water, you are drinking water in its liquid state. You might cool the water by placing cubes of ice in it. The ice is water in its solid state. If you leave p Figure A.2.1.3 generator season; in cells generators energy Installing readiness have to an for electricity the hurricane mitochondria produce ATP for as all their their needs 19 835292 CSEC HSB Unit A Topic 2.indd 19 08/01/2015 15:57 Matter and Movement energy into and out of cells the glass of water in the Sun for several hours you will nd that its volume has 0 Key decreased because the water has evaporated. Water evaporates to form water terms ! vapour, which is a gas. Kinetic energy The energy of SOLID LIQUID GAS movement. ice ATP cells A molecule when they formed respire. by It melts liquid water evaporates to all processes in Par ticles cells. move that small All the occur Anabolism which condenses energy-consuming Metabolism changes vapour provides freezes energy water all All a more solid move slowly t han more slowly t hose in a t han gas. t hose in a liquid To move from par ticles move faster) one which, state to in turn, anot her chemical in the in the adding energy (making par ticles (making or removing energy body. reactions molecules involves are move slower). in made Energy into large molecules. Catabolism which large down into All the reactions molecules smaller are in broken ones. Study Respiration energy Heat of provides on your is as t he t he exists energy (see ability ability in transferred Light photosynt hesis cells with Remember this their (see page of many from 32). do forms one enables page to par ticles work. to – place green do heat, to kinetic as light anot her plants Chemical The work to energy by energy result and make is a t he t heir movement food stored of chemical. in during t he through the book 58) (see below). learning notes. Do respiration with and in cellular stores such as starch, glucose and food we eat fat as transfers are ver y impor tant in biology. During respiration, cells and energy-rich molecules of carbohydrate, protein and fat, and not use confuse is Energy energy breakdown write dened above tip needs. read best par ticles. Energy you is described movement. o ___ ✔ Energy some of the energy released to make a substance known as ATP. This breathing. molecule is the way electricity to we use provide ‘energy energy for currency’ in the of home. anabolic all cells. ATP Cells moves chemical use easily reactions to ATP much like throughout occur to the the move cell some Questions substances from 1 Explain the between a atom each element c atom of and and these pairs: d 2 does anabolism not body. function compound, ion, ATP t he molecule, to and to move cell str uctures, such as vesicles, anot her. of have sur vive Each electricity and and place membranes difference and b one across long needs in to mitochondria in to cell t he use home, a t he (see t his generator blood, generate is to page like so its 5). To homes make we own do not ATP return t hat for to are transpor t itself. our not it That around is t he comparison on t he wit h electricity grid electricity. catabolism. Which particles have the Metabolism most kinetic energy: those The metabolism of the body is all the hundreds of different types of chemical in a solid, those in a liquid or reactions that occur in our cells and in the gut. Metabolism is divided into: those in a gas? ● 3 a Where is ATP made anabolism, form cells? b What is ATP What form taken in of energy a green b in which small molecules combine to larger ones, t hem e.g. glucose starch. These of ten require energy to happen. catabolism in which large molecules are broken down into These of ten release smaller metabolism occur is ones, plants, e.g. and reaction is ● by chemical for? make 4 a inside glucose carbon dioxide and water. energy. animals? speed wit h metabolic The rate. which t he reactions of called t he 20 835292 CSEC HSB Unit A Topic 2.indd 20 08/01/2015 15:57 Movement A.2.2 into and out of cells Movement Movement across cell surface membranes surface the end cells are surrounded by cell surface membranes (see page 5). This is to t he movement of substances. Membranes are for keeping be t he cell, such However, state as t he proteins, sugars and fats t hat it has made t hey need that a cell cells to needs need to take in substances from t heir cell surface remove substances t hat are harmful. Any molecule or define to use, or needs to get rid of, must be membrane. These membranes are membranes because t hey allow able to described some but not Movement across membranes active transport get membranes as anot her. liquid is t he You into a t hroughout movement can occurs of by one molecules, demonstrate glass all state a liquid, the substances to of t he t he wit h explain are so water. water par ticles each diffusion Af ter in t he have ot her. concentrated molecules of t hree met hods: the a while or by ions, from putting t he a one drop coloured place of 0 in have Key Fully spread more kinetic collide energy wit h each and move ot her a lot in t he drop. But t he drop is and t hese collide wit h t he a par ticles drop wit h spread lots of out into coloured t he water. par ticles Af ter a by a The where t hey par ticles are concentrated Diffusion or ions, (in t he depends in two continue concentrated to (in spread t he as t hey drop) to a move place plants size that to t here from a on are to a t he difference Molecules, place concentrations said to diffuse so A will through, is wit h called down in T o activity this works you a are best 1 Fill 2 T ake if use one of the small a t heir much to all you or in t he ions, concentrations diffuse a low from concentration. concentration concentration have top in need and a school the drop all of ions to them. The from net a movement place with a of high concentration to a concentration of molecules. place with a low a of place molecules, wit h a high Osmosis The water a from The gradient. difference Ions and net place concentration of diffusion with solutes through a a of low (dilute partially between permeable membrane with concentration to a place molecules a high of solutes gradient. solution). transport molecules and The ions movement across the the release using a a concentration energy from small with bottle middle the is two some liquid food tall glasses or eye dropper similar colouring, clear plastic to the which vessels. dropping you can This pipettes orcollege. vessels off against respiration. store, you at not less liquid grocery may but yourself Diffusion in that and place t hey gradient do membrane still membrane buy of coloured of a molecules t he Active this an walls through. molecules (concentrated Tr y to cell permeable some solution) t he allow pass to water). places. concentration and by too, lighter where Applied membrane because par ticles while, sur rounded organisms. terms molecules liquid. of active around sur rounded coloured living permeable articial of glass. They and ! to coloured par ticles transport Diffusion be importance d iffusion, pass coloured osmosis diffusion allows water between and osmosis, membrane t hey transport difference pass Partially colliding diffusion, active parti ally any In terms and t hrough Diffusion Diffusion cell ot hers. osmosis or enter through ion ● t hrough, cells the diffusion permeable you surroundings ● its topic to: substances leave osmosis t hat this for ● and of able surface itself. outcomes t hings and inside membranes a ● barrier surface membranes should All cell Learning By Cell across water. of of food the colouring vessel. Do and not use the squeeze pipette the to dropper put a too drop. 21 835292 CSEC HSB Unit A Topic 2.indd 21 08/01/2015 15:57 Movement across cell surface Movement membranes 3 Watch to the take record 4 Try e.g. Many p Figure the top of the A across ● The ability t hrough it or tip will moves from have them another cells. kinetic across and place a is a the few water. hours Use later. your Keep cells phone these as a T ake put some to do as not cold photos see if in a water after there release have shown ice Figure one certain is single pipette in any intervals and of hot time, difference. drops just vessel if you a drop add invert of them the or colouring to A.2.2.1 does gradient – depends t he steeper on: t he gradient t he faster will be t he many molecules smaller t he membrane. t hrough of The t he and ions molecule, more or lipid membrane. to pass ion, t hrough t he faster soluble This is t he it cell will par ticle because lipid membranes. move is is, t he t he faster main membranes. ve r y i mp o r t a n t place which to surface place diffusion is a p a s s i ve in t he m ove molecules m ove m e n t b o d y. as we As do far n ot as cells need a re concer ned, energy f ro m AT P to not Molecules, from is membranes a energy, one cell membranes inside which from t he component diffusion process, ATP ions, that of t he move Diffusion Remember need through and of rate. Generally Study cell concentration diffusion passive time colouring you water start out observe. minutes, food If disperse the and A.2.2.1 ● ✔ 15 at this other. of them. you but and bottles Diffusion 0 what 10 colouring photos again, in 5, squeeze the of this water food some into of t he t he h ave molecules to m a ke m e m b ra n e , to human s u re as a c ro s s and we ions t hat can cell is t h e re see sur face m e m b ra n e s . re s p o n s i b l e is wit h a fo r t heir c o n c e n t ra t i o n t hese e xa mp l e s The k i n et i c m ove m e n t . g ra d i e n t of a c ro s s diffusion energy We o n ly t he in t he from t he body: cell. ● Exchange ● Absor ption ● Movement blood ● ● into of of and digested oxygen carbon Movement of a ner vous oxygen and glucose t hese water will by be t he small dissolved dioxide and across diffusion dioxide t he lungs. intestine. nutrient a waste out synapse by an Bot h same glucose Af ter on glucose molecules of cells (gap) into t he between bot h Cell A.2.2.2 membrane and a molecules, t hem. Figure ar ticial diffusion. t he of t hrough subst ances. equilibr ium are movement from in in blood. ner ve cells in water while, sides of membranes shows t hat is two fully molecules t he water, can membrane, are solutions of per me able pass concentrations t he ions, as of to t hrough glucose you can t he and see in A.2.2.3. molecules to t hese separated dynamic lef t allow subst ances. Figure and chemical carbon to membrane food dioxide system. membranes per meable carbon cells. of Cell to oxygen Movement t he A of r ight lef t r ight to still means and t hen moving, no eight r ight, has but t here is been but overall move if ten no set t hat up. Dynamic t here movement, is no e.g. from r ight to move from r ight net if lef t, t hat t he net movement. ten molecules t he to means net lef t Net move movement and ten move is from two from lef t movement. 22 835292 CSEC HSB Unit A Topic 2.indd 22 08/01/2015 15:57 Movement into and out of cells concentrated glucose (less glucose water) (more - • solution water) • • • • •\ • dilute solution \ Movement • • • • • • •• • • • •I • • ,,..;; • +-• • • •• · I· ./ . ' • fully = p • A.2.2.2 water and permeable = Movement glucose of by p water a fully • • A.2.2.3 when the either side A dynamic concentrations molecules of the still movement diffusion membranes '• glucose Figure molecules through membrane = surface • membrane glucose Figure of permeable cell • • / • across from one but side water equilibrium; are the membrane, occurs = there to same on movement the is no of net other Osmosis As you read t his section remember t hat a solution is of a solvent dissolves made a solid, and concentrated one or more solutes. Water is t he usual solvent and liquid glucose gas, whic h separated it whic h by is a only t he solute. par tially allow Figure A.2.2.4 per meable small shows membrane. molecules t hrough – two This in glucose has t his solutions pores case (holes) water, but in not glucose. is a solutions called special in t he case which of diffusion. water is t he It diffusion (i.e. solvent (t he chemical dissolved in it is of t hem solute) a of water dilute a par tially molecules solution) concentrated ● to a from region a region where where t here are t here fewer are of lots t hem (i.e. a solution) permeable membrane – one t hat will allow free movement t of molecules, Figure A.2.2.4, but t he not net of ow t he of solute water • partially = water In (more movement of water is an will example permeable is membrane a high t he from equal Importance Animal cells Animal cells cell called a diffusion place concentration become no net and of t here blood The water a low solute. is a t herefore of be from right to lef t. p Figure to It living cells by by a T wo glucose partially = water solutions permeable par tially until of permeable solute t he two to a water place wit h the from there the solution on is net solution the movement on the of right to left concentrations equilibrium. cells permeable suspended concentration a concentration continues par tially are membrane • A.2.2.4 • osmosis. t hrough dynamic surrounded Red plasma. wit h of osmosis are walls. of • glucose membrane; Osmosis • molecules. separated This solution water) \. involves: • ● water) 1. ,/•/ Osmosis ● glucose . -.~ .I ·. .... . ·1.. . . _,, . . I . •\.• • .:. .•..\. _.,, .. • (less or dilute solution of in plasma t he membranes. liquid remains par t of relatively They t he have blood constant all 23 835292 CSEC HSB Unit A Topic 2.indd 23 08/01/2015 15:57 Movement 0 across cell surface Movement membranes t he ✔ Exam tip ● Never use ‘strong’ time what and a so describe solutions. ‘concentrated’ and red blood happen solution to a cells red do not blood change cell if it in were size. Figure placed wit h a solute concentration higher wit h a solute concentration lower t han and out A.2.2.5 of cells shows in: plasma – net ow of ‘weak’ water to t hat would into out Use ‘dilute’ instead. ● a solution water t han plasma t Cell surrounded more net cell by concentrated flow water is a solution than that is plasma Cell is surrounded more dilute by than a solution net of scale marked flow water • ~ becomes is cell \ ow of Figure A.2.2.5 effects of on blood The of red osmosis cells in bursts (lysis) ; \ tube net that plasma out crenated glass – in. with 250 in mm 200 In our bodies we have mechanisms t hat keep our blood plasma not happen. at a 150 constant meniscus 100 solution the 50 of the moved concentration, so t hese changes do sugar up tube Written Activity 0 Observing and recording osmosis water A student which sugar solution Visking is surface set also up the known membrane. moved up regular intervals the tube. apparatus shown in Figure as tubing, is partially Visking Over The and a period student recorded of time used them in the a the A.2.2.6. meniscus scale Dialysis permeable to take of tubing, like the the sugar cell solution measurements at table. (dialysis) tubing Time/minutes Position of the meniscus in the tube/mm p Figure A.2.2.6 Answer the a 0 0 1 24 2 52 3 73 4 102 5 127 6 138 7 180 8 190 following 1 Draw graph 2 Describe the of questions. the results student’s shown by results your in the graph. table. [6] [2] 24 835292 CSEC HSB Unit A Topic 2.indd 24 08/01/2015 15:57 Movement into 3 Calculate 4 Explain over the Osmosis Plant wit hstands Eventually of t he This to stems so the a of cells Movement movement in mm per minute of the across solution t he as cell When pressure will turgid. moved and be If ow of up t hey resists t he cell is and kept It a the of lef t tube. ow in t he t he rigid against of t he into cell water t he water t hat ‘stiffness’ can more into permeable water cell t his is a plant wall, into and t he t he anot her cell which cell. cell is example before. pressure and of to builds t heir suppor t up in t he leaves, cells, owers t hemselves. is and Stems of 0 Key do not have wood, stand erect and leaves are at right angles stem to absorb most ow a of away plant water from cell out t he is by cell so in osmosis. a a concentrated The vacuole movement t hat solution shr inks is t here and called t he will be a net cytoplasm pulls cell, like t hat in Figure A.2.2.8, is water The tissue is no is but instead it is wilt of on t he hot days. direct rays descr ibed The of as accid. This is what happens to light of do advantage t he Sun, so of wilting t hey are is t hat protected t he leaves against A cell not that has because push lost the against cell the are The movement of plants cell surface membrane away taken damage the cell wall when the cell by loses high full push wall. from out is longer the t hat which contents wall. limp Plasmolysis turgid, cell the cell cell and contents plasmolysis. plasmolysed. the Flaccid cell The A that sunlight. placed wall, cell to against When terms ! water, t he membranes [4] par tially ow water described gives t he net pushes t he ow we is and net plants. are around no water, for wall t here swells equilibrium useful t hat cell. cytoplasm t here t hat surface meniscus Turgid plants, cell [2] sugar cellulose each t he inward rate of minutes. dynamic extremely out plants of osmosis, referred 8 have membrane by the why in cells and water. intensities. cell wall – fully permeable nucleus • molecules cell surface membrane of solutes • vacuole cytoplasm concentrated water inside --.... dilute More water solution The cell p solution molecules Figure molecules inside pressure the of cell the pass to from the solution the solution outside the solution cell into the cell outside the cell the cell than from the outside in the vacuole increases, pressing the cytoplasm against the wall A.2.2.7 A turgid plant cell 25 835292 CSEC HSB Unit A Topic 2.indd 25 08/01/2015 15:57 Movement across cell surface Movement membranes cell into and out of cells wall nucleus cell molecules surface membrane vacuole shrinks of solutes cytoplasm from the pulls cell away wall water dilute solution inside molecules the • • More water solution The pressure cytoplasm well excavated grains of here and sucrose dish of of pass cell the solution against the to from the cell the the • concentrated solution inside the cell to solution the outside outside than the cell from the inside in the wall; vacuole eventually decreases, the reducing cytoplasm pulls the away pressure pressing from cell the the wall containing (not salt) p Figure A.2.2.8 A plasmolysed plant cell water Roots peeled molecules outside • cell have specialised cells, known as root hairs, which increase t he surface portion area available for water uptake by osmosis. Water moves from the soil into the root hair cell by osmosis. Water moves from the root hair cell across the cells of the root to the hollow xylem vessels in the centre. Once the water is in the xylem it is transported to the rest of the plant. unboiled p potato Figure boiled half potato half - A.2.2.9 Key Net movement water by soil of particle osmosis soil water root xylem the cortex vessel carries water rest of hair cytoplasm cells to the plant Lower p p Figure A.2.2.11 very large give a water Plant number large from of surface the roots tiny area have root for Figure A.2.2.10 water concentration Uptake of water by High a root water concentration hair a hairs to absorbing Tr y soil this yourself Requirements ● a large ● a sharp Irish knife potato ● a white tile or scalpel ● two ● a bag dishes ● a spoon of sugar (sucrose) 26 835292 CSEC HSB Unit A Topic 2.indd 26 08/01/2015 15:57 Movement into 1 Cut a 2 Remove large shown 3 4 one Using a the half the each of cells potato 10 mm diagram in sharp in into in across cell surface membranes two. circumference of peel from cut ends each half the as below. boiling knife, Movement or water for scalpel, 10 minutes. carefully make a well in as diagram. half in a separate dish containing water to the level seen in diagrams. 6 Place 7 Leave 8 Observe a Irish the Place Place out about in shown 5 and some for sucrose roughly the in 24 pieces each well (about half way up the sides). hours. of potato and write a record of what you see or take photograph. Tr y this Softening up yourself an eggplant Requirements an ● if eggplant they firm, not ● some ● a 1 are (or two small; or three must be five ● very soft) salt ● permanent ● scales cups or other small marker stirrer Weigh out 58 grams of table or cooking salt. 3 2 plastic containers Dissolve the salt in 1 dm 3 of water (1 dm is the same as 1 litre). This -3 is a solution stock 3 Pour it 4 with the concentration of 58 g dm which we will call the solution. some of this some more solution to half-fill one of your containers and label A Pour half full and Y ou now of label it your B. stock Fill this solution into container another with water container and stir so it is thoroughly. -3 5 Pour C. 6 Pour it half Fill D. the have of this half Fill a the solution contents container of this solution the of with contents container from that has of container concentration container water with a and container water D so B stir C and that into third 29 g dm container and label and label it thoroughly. into stir all a of a fourth container thoroughly. the Pour containers away have the half of same volume. 7 Half-fill a 8 Cut eggplant an fifth containers 9 After 10 decide container and five place minutes how into they with have the and equal-sized them take water into the pieces changed label pieces different out over of the the it E that just solutions solutions, fit into you feel time they have changes that you the have them been in made. and the solutions. 10 Use the term osmosis to explain the have observed. 27 835292 CSEC HSB Unit A Topic 2.indd 27 08/01/2015 15:57 Movement across cell surface Movement membranes into and out said to of cells Questions 1 Suggest 2 process. Look Figure at a reason reason. What c effect Which do will the you becoming your would of through A.2.2.2. for What movement 4 diffusion passive Give 3 why What a partially glucose or will happen b What will permeable molecules would dilute surface membranes to the is glucose happen to the be a molecules? water? Give a eventually? happen think more a answer. cell be more in membrane Figure harmful more becoming – have on the A.2.2.2? our blood plasma concentrated than our red 1 blood cell low surface concentration outside membrane cells? cell 5 Explain and high why leaves 6 How does 7 Explain 8 Create 9 Explain it b is important help wilting how that the following are held upright: a stems flowers. root a hairs plant survive absorb during a hot day? water. concentration inside cell a table why to compare energy is the processes needed for active of and diffusion active transport. transport. 2 tneidarg • • molecule into 10 fits protein State noitartnecnoc Active - ~~ - ••• • • are cells to substances ). Cells pump as uses ATP to of active have also need and Examples of Table to outside use t heir to use They of use same t heir ATP occur q T able out in of of source t he of bot h t he helping to keep our cells cell active This means t hem of t hat against energy to at a t hey t heir move t hese against concentration transpor t. animals energy we functioning A.2.2.1 Examples Cells of active transport Substance active and plants consume is as shown used in in active properly. in plant moved and animal cells Reason transport process direction) Root hair cells Nitrate ions magnesium the ••• • •• move are repeated Plant ~ t he to t hat the (and - as surroundings cytoplasm. energy process one-quar ter by is t heir the Organism the in t heir substances t he transpor t About t han some from cells. move t hey active A.2.2.1. substances gradient. into gradients transpor t, into across membrane 4 transport. move molecules cell energy require concentration going concentration - - ..- •\C•W- examples transport Sometimes lower •• 3 four pump and ions (into are used ions are for making used for making are into cells Potassium against ions (into T o help T o open absorb water by osmosis for diffusion the the cell acids chlorophyll Guard moved ions amino Magnesium cells) -molecules Nitrate cells) the stomata of their gases into and out of the leaves concentration gradient Animal Red blood cells Sodium the Nerve p Figure A.2.2.12 A protein cells the cell surface membrane molecule against a into the cell T o prevent water Potassium ions (into T o and help in them absorbing too much expanding cells) the transmission of impulses cells Glucose (into the Absorb glucose into blood from digested food concentration from gradient of moves Epithelial a (out molecule the in ions cells) by the small cells) the to provide energy active intestine transport 28 835292 CSEC HSB Unit A Topic 2.indd 28 08/01/2015 15:57 Movement Figure into and A.2.2.12 molecules out of cells represents across Movement one membranes way via in a which protein energy ‘pump’ in in ATP t he is used to across cell surface membranes move membrane. Summary Movement ● A chemical simpler An or ● ● element of is a the smallest the atoms of different Energy exists energy and Particles are molecules Diffusion all the is the moving the heat be two element. broken or down more Ions are to a elements. Molecules elements. energy, a about light Catabolism down place in that are particles charged energy, all smaller atoms chemical low a kinetic small the energy. within the body. molecules reactions in are built which large ones. substances with of occur which includes into of because reactions reactions movement to an more forms: chemical broken concentration of of atoms. all ones. are or cannot made energy. includes larger one that are particle of constantly is substance different kinetic Metabolism into in cells Compounds is groups up out from Anabolism ● and substance. atom made ● into from a place concentration with (down a high a concentration gradient). ● Substances active ● permeable as water), membranes ● Osmosis a cell surface membranes by diffusion, osmosis and transport. Partially (such cross is and a membranes but not dialysis special dilute solution large to a allow ones membranes type of more the (such are diffusion in movement as partially which concentrated of sucrose). molecules surface permeable. water solution small Cell moves across from partially permeable membranes. ● If animal cells osmosis, solution ● they cellulose cell cells animal they by are wall cell ● said to pump get ● rid their in of the If water, resist into and the swell, but crenated. cytoplasm the and of need burst They are they into surface water very dilute to they have by a turgid. solution, red immersed by gain a because are happens water are gradient they not cells cell They solution immersed concentrated this lose movement that do very plant also plasmolysis. is a When If dilute are expansion. into shrink. concentration very cells their they a plant immersed substances of Diffusion to be causing transport against burst. solution, pulling wall Active are osmosis concentrated shrinks immersed and absorb If water are swell osmosis. they lose blood cells into a very The vacuole membrane away from the flaccid. substance using and across energy pump from them a membrane respiration. out if they Cells need to them. and osmosis molecules are passive themselves processes rather than ATP relying on supplied the by kinetic energy respiration. 29 835292 CSEC HSB Unit A Topic 2.indd 29 08/01/2015 15:57 Practice Movement Questions Which Practice 1 Some responsible for t he upward out of cells t he sugar solution A plasmolysis B osmosis C diffusion D active in t he movement tube? A sugar Visking solution (dialysis) drops of of bag. red food was put tubing as inside shown colouring were a bag made in t he diagram. added to inside a t he from Two t he water. The Af ter star ted to bag ten turn was t hen minutes red. t he Which put water caused in beaker t he t he beaker water transpor t contents 5 in is and Questions of Section process into to Which process animal cell? results in t he movement of water into an of had A diffusion B active C osmosis D absor ption change transpor t colour? glass rod 6 Which substance enters an animal cell by active transpor t? visking sugar red tubing solution food A carbon B potassium dioxide C oxygen D water and ions colouring water 7 A bag of Visking tubing contains a concentrated beaker A solution of of sugar dilute sugar. B active C diffusion D osmosis Which Changes is an example Oxygen moving B Mineral ions C Water D Carbon of osmosis into t he moving entering t he dioxide into root moving in root out root hair cell. root hair t he hair a hair cell? into will a beaker happen is an A Carbon B Water example dioxide into a Magnesium Potassium The of t he sugar solutions af ter to an t he hour? of ions ions apparatus into flaccid of diffusion a t he root into into into shown mesophyll leaf a in a in the the concentrations Visking tubing of bag the In sugar the solutions beaker A increases decreases B increases increases C decreases decreases D decreases increases cell. hair cell. a plant Which is required for active transpor t to take place into cell? a 4 Which cell. 8 Which D placed transpor t A C is dissolving Inside 3 bag solution. concentration 2 The cell? cell. A Energy. B A C Formation D A cell. root guard t he hair cell cell wall. cell. of diagram a was set tube scale marked high vacuoles. concentration of solutes outside t he cell. up. 9 glass of stoma. A sample of red concentrated with blood salt cells was placed solution. The diagram into a shows t he 250 in mm appearance of t he cells. 200 150 meniscus 100 solution the of the moved sugar up tube 50 0 water Which A sugar explains t he Water entered B Water lef t C Salt entered D Salt lef t appearance t he cells by of t he cells? osmosis. solution t he cells t he by cells osmosis. by diffusion. Visking t he cells by diffusion. (dialysis) tubing 30 835292 CSEC HSB Unit A Topic 2.indd 30 08/01/2015 15:57 Movement 10 into Which and process respiration in A active B cell C diffusion D muscle out of does cells not Practice require a supply of energy from 2 cells? a What b Describe cell transpor t c oxygen B Visking t his • it of in tubing is similar to cell surface membrane The is par tially permeable. Some students i) salt. what what pure happens water, ii) a when an animal concentrated [6] is meant by ‘more concentrated [1] Compare t he permeability terms of cell flaccid, of cell walls membranes. plasmolysis wit h t he [4] and turgid refer to in plant t hat placed Explain [1] explain permeability e 1 water? and solution’. contraction d Section pure solution division of is is Questions cells followed Explain t he meaning What meant of each of t hese terms. [3] procedure. Six pieces length were filled weighed water of with the The bags in large • Af ter wit h Visking tied 10.0 g. • a of were six at a beaker paper sixth measuring to make sugar bag a 140 mm bag. solution was filled in Five bags until they with 3 b of towels cotton distilled bags and t hread and d removed, reweighed. The blotted results in t he what why t he par tially when solution diffusion permeable of a plant salt. cell is placed in [6] t hrough cell membranes is a [3] term diffusion term happens process. Explain t he dynamic across cell equilibrium membranes. as it applies [4] are 4 shown Explain to dr y by [2] concentrated passive suspended water. were is Explain a distilled c wit h t he a membrane? mass. tied hours, end different The same were tubing one a All human cells carr y out respiration to provide graph. t hemselves wit h energy. 22 Explain why membrane 20 cells. g/sruoh b 18 is across impor tant for t he cell surface respiration in human [6] Identify four diffusion. c diffusion Describe factors which affect t he rate of [4] and explain what will happen to a piece 6 retfa of 16 potato when solution. placed in a concentrated sugar [5] ssam 14 5 a Describe t hat two simple diffusion experiments occurs in air and in to demonstrate water. [6] 12 b Explain t he between two similarities osmosis and and diffusion. t hree differences [4] 10 c 0 60 180 120 240 i) Suggest why a cell needs energy for active 300 transpor t. [3] –3 concentration of sugar/g dm ii) a Explain i) why t he included water; ii) t hem. Describe c Explain d A t he t he not e of active transpor t. [2] a bag t hat contained distilled dried t he bags before weighing results results shown of t he in t he graph. [4] students’ [5] criticised t he results saying t hat t hey were reliable. State t he examples [1] investigation. student two [1] surface b Give students: how t he results Predict bags if what lef t procedure more will for prediction. should reliable. happen anot her 18 be changed to make [1] to t he hours. mass of t he Explain your [3] 31 835292 CSEC HSB Unit A Topic 2.indd 31 08/01/2015 15:57 Unit A Photosynthesis, A.3 Learning By the end and A.3.1 outcomes of this topic be able define the process state the of photosynthesis to: term is t he process by which green plants make t heir own food. photosynthesis They ● webs Photosynthesis Photosynthesis ● chains you The should food food requirements do t his by conver ting light energy from t he Sun into chemical energy for in glucose. The glucose t hat is made by t he plant is stored as starch and photosynthesis also ● explain what happens conver ted into many ot her molecules. The following are needed for during photosynt hesis to take place. photosynthesis ● ● describe the fate of Chloroplasts chlorophyll products of in cell str uctures t hat contain t he green pigment the and enzymes t hat catalyse reactions to make glucose. photosynthesis. ● Light ● energy Carbon ● Water The eit her dioxide of (some used respiration Overall, we of can by t he t he root Sun which by write is hairs used ot her a or from by + e.g. lamps. are by glucose t he (which plant). The can rest be is stored excreted as starch), and can be organisms. word dioxide sources, osmosis. equation for light carbon ar ticial atmosphere. photosynt hesis oxygen in from absorbed products from photosynt hesis as follows: energy water glucose + oxygen chlorophyll A p Figure A.3.1.1 The success of simplied chemical equation for photosynt hesis light such as these bananas depends + 6H 2 understanding of and why plants food for O C 2 need to produce themselves and H 6 photosynthesis O 12 + 6O 6 2 chlorophyll carbon own energy on 6CO an is: crops dioxide water glucose oxygen their us Practical T o test a leaf for Activity the presence A.3.1 of starch Requirements ● a suitable ● a beaker, leaf, e.g. ● a water ● a test ● a thermometer ● forceps ● a ● ethanol Hibiscus ● dilute iodine in potassium iodide 3 The p Figure crop of need and A.3.1.2 corn plenty good materials water T o produce (maize), of light, supplies for and these high of a at 85°C ● Bunsen burner or electric water heater tube white a solution) tile biochemical test for starch ● a ● gauze ● eye ● matches involves tripod protection which is brown, starch simply turns blue-black. checking However, whether leaves cannot iodine be solution, tested for plants by putting iodine solution on them because: raw photosynthesis carbon bath (iodine good temperatures the solution 250 cm ● the ● leaves chlorophyll in leaves makes any colour change more difficult to see – are not very permeable to iodine solution. dioxide 32 835292 CSEC HSB Unit A Topic 3.indd 32 08/01/2015 15:58 Photosynthesis, For these food reasons 1 Remove 2 Place it the in chains the leaf following to boiling and be food for Photosynthesis procedure tested water webs from 20 the is used. plant. seconds. This makes the leaf more boiling permeable 3 Ensure to that the all iodine Bunsen solution. burners ethanol are turned leaf off. water at 85°C 4 Place the ethanol leaf and in the a test leaf tube in a of ethanol. water bath at Place about the test 85°C, tube as with shown the in gauze Figure 5 After A.3.1.3. 10 The minutes, ethanol remove will the boil leaf and from de-colourise the ethanol the and leaf. wash it in the tripod water 6 bath Spread to the cover record for 20 leaf the your seconds. out leaf on and a white wait for tile 1 and add minute. enough Pour off of the the iodine iodine solution solution and p observation. Figure A.3.1.3 ethanol 7 Record the colour of the I Bunsen o_ _ _ _ o the lid Wear i.____ is of ammable. the eye ethanol protection All Bunsen bottle and is burners must be turned off choose light be t hat two and tested shown plants t he for in leaves in starch Figure produce from ot her t he t he using take care not to burn l yourself. starch same dark. t he when species; Af ter a t hey for week, procedure 1 are photosynt hesising, week a leaf described keep from one each above. The shows starch are t hat Key used destarched. destarched a up. A Plants plants, leaf plant plant in t he and should results leaf t hat are Practical T o find out if a plant kept in t he wit hout have used t he Activity needs any been in dark in for stores t he next a of dark t hree week all starch for a is of stores described week, practical its known which energy near this such apparatus and from has use carbon Destarched are The chemical plants it absorb to make dioxide water. been week, is in lights terms by glucose A.3.1.4. if burners Photosynthesis is This heating naked ! light check When place before removed. process To not leaf. as Ethanol do in so that up used plant the in A dark all of plant for its that about stored a starch respiration. of as as a leaf kept in the b light leaf kept in the dark activities. A.3.2 chlorophyll to make starch Requirements p Figure two ● as ● leaves for Practical Activity a variegated plant that has been Y ou will The plant several 2 Pick need a plant should with have The see if results plants of testing produce variegated been leaves, destarched when kept for a week in (a) the testing with destarched light 1 to A.3.1 starch from A.3.1.4 leaves and e.g. variegated then put in the and (b) the dark Hibiscus. light for days. one of upper side, green and the leaves making the a and clear non-green make a drawing distinction areas (such of its between as the Figure A.3.1.5a). 3 Using the method in Practical Activity A.3.1, carry out Before a starch test on the whole with Figure A.3.1.5b shows the testing After leaf. results. p Figure iodine solution iodine solution A.3.1.5a p Figure A.3.1.5b variegated leaf The for results of testing a starch 33 835292 CSEC HSB Unit A Topic 3.indd 33 08/01/2015 15:58 Photosynthesis, Photosynthesis Practical T o find out if a Activity plant needs food chains and food webs A.3.3 light in order to make starch Requirements ● as ● a for ● foil 1 Y ou for 2 Practical potted or black will a paper need a a strip upper shown stray in A.3.1 the and plant 3 Put 4 After in dark paper which can the for a week clips has plant for reach in paper sides A.3.1.6a. paper several it black lower Figure of the of and light edges test Activity kept been destarched a Practical a Make leaf foil) leaf, with pick using Activity A.3.1.6b. to sure under a in the dark b no the the the bright leaf light. and method p in Figure if a the The result leaf of in testing a A.3.1. shows Practical out A.3.1.6 shows the Activity plant to see if plants need light results. to find it as leaf T o placing foil. place days starch the (or of b Figure by week. Attach the plant needs photosynthesise A.3.4 carbon dioxide been the in order to make starch Requirements ● 2 potted ● 2 polythene plants that ● 2 elastic ● dish of soda ● dish of saturated have in dark for a week to destarch them bags bands lime sodium hydrogencarbonate solution saturated 1 sodium hydrogencarbonate releases carbon solution Put a dish cover the saturated with a sodium hydrogencarbonate polythene bag secured solution tightly with inside an a elastic pot and band. dioxide Sodium 2 polythene of plant Prepare hydrogencarbonate another potted solution plant in breaks exactly down the to same release way, but carbon use dioxide. soda lime, bag which 3 Put 4 After absorbs the plants several carbon in the days in dioxide. light and leave the light test conclude from the a them leaf for several from each days. plant for starch. Questions 1 What can you results shown in Figures A.3.1.5b and dampened A.3.1.6? soda lime absorb to carbon 2 Explain why the potted plant with saturated hydrogencarbonate solution dioxide elastic should be used in Practical Activity A.3.4 (see Figure A.3.1.7). Figure A.3.1.7 band 3 p Figure A.3.1.7 T wo potted plants Predict like one provided one without with any carbon carbon dioxide dioxide what the leaves from the two plants in will look – after testing with iodine solution. and 4 Explain why destarched plants should be used in these practicals. 34 835292 CSEC HSB Unit A Topic 3.indd 34 08/01/2015 15:58 Photosynthesis, food chains and food webs Photosynthesis It is very difcult to quantify how much starch is produced by leaves. The iodine test tells us that starch is present, but not how much. This means it is no good for telling us how much photosynthesis goes on in a plant. It is much easier if we look at using oxygen, the by-product of photosynthesis, instead. Practical T o demonstrate Activity the evolution A.3.5 of oxygen by a photosynthesising plant Requirements ● a test ● a glass tube beaker, ● a ● pondweed, ● a glass funnel ● 2 funnel ● ● stop clock ● sodium ● scissors water ● a a thermometer ● matches ● a lamp An aquatic 3 the rate gas are the 1 of supports plant, released of Assemble as to and can the 2 blow 3 pondweed Check Record many 4 that the with the the are light for of or can be plant Remove the lamp counted the bubbles These bubbles by number of so number of adding solution under is Figure a or if Use either by amount using of investigate bubbles oxygen, of one of warm using water a sodium solid). Cut a short length water. bubbles. produced over 60 seconds by to shining that a lamp acclimatise the step to produced conditions 3. bubbles Again, are the new over wait produced onto the (longer 60 the 3–5 over apparatus. if not Wait environmental seconds same as (or conditions. longer). when you minutes. 60 seconds evolved tube collect to small contain A.3.1.8. small 1 g producing bubbles in in concentration, (largely test used photosynthesises, produced). intensity the shown bubbles being 6 the it as dioxide pondweed Record Count cut splint pondweed, plant counted. (0.1% 5 7 the the scissors number minutes be carbon through bubbles Increase 3–5 As apparatus the hydrogencarbonate of Canadian freshly hydrogencarbonate photosynthesis. increase straw such photosynthesis. products and 250 cm (or longer). gas oxygen) to bubbles bubble 0 of 0 gas 0 glass 0 (transparent) 1~ ------1 beaker ~o f ' - - - - - - ' I 0 0 0 warm 0 0 with 0 carbon freshly water dissolved dioxide cut pondweed glass (transparent) funnel to gas bubbles test tube p (to into water to Figure of support direct A.3.1.8 aquatic The apparatus to measure the rate of for funnel allow to fresh circulate pondweed) photosynthesis plants 35 835292 CSEC HSB Unit A Topic 3.indd 35 08/01/2015 15:58 Photosynthesis, Photosynthesis The apparatus various in factors pondweed. Figure on These temperature, and t he A group of carbon dioxide species an They of used distances are in the Light effect a light ruler of light used light the intensity aquatic from be Figure A.3.1.9 freshwater bubbles in the of bright to and light plant oxygen; water animals In aquatic plant and the a 1 Plot 2 Describe a apparatus that to intensity they meter give a 5 The are o ___ it does very not store cells starch with dissolve ● ● instead than in if the be cell nd out photosynthesis found in a of a light local bench how of a stream. lamp intensities. units Rate of at different Their results photosynthesis /number bubbles per minute 6 40 18 60 24 100 25 a of main the student’s your graph results. shows [6] about the effect of light intensity [4] realised how reasons students plant that they for they could the shape compare the results to stream. valid comparison Suggest between photosynthetic a light intensity the how that you with they have drawn. another would [4] species do this to plants. [3] products photosynt hesis use for [2] graph wanted Plants reading the another of no this. of from product had get t he is glucose, glucose made which in is a sugar. All photosynt hesis sugars for t hings. Much of the glucose is converted into starch and then stored. Starch, like Conver ted into t he Conver ted into ot her make so in is insoluble complex sugar sucrose for transpor t. water much stored just plant cell carbohydrates, such as cellulose, which is used to walls. as kept Combined wit h ions containing t he elements nitrogen and phosphor us – to and make nucleic acids (DNA and RNA). more ● can to of glucose? glucose, compact, glucose A.3.1.8 photosynthesis rate position range of glucose, is a carbohydrate. The rest of the glucose is used in a variety of ways. ● is light, tip plants unlike Figure rate 10 carbohydrates. several Starch, the 20 what Suggest Suggest The their of of as plant. 4 Fate lling in the had to on 30 of students 0. make ● graph the The of of wavelengt h such for of do effects dissolve oxygen 3 Why t he t he plants webs concentration inuences light plant intensity /arbitrary microbes Study aquatic food table. this on ✔ investigate of and produces some provide to intensity, of p used chains Activity students the can photosynt hesis are the increasing of factors Written Investigating A.3.1.8 rate food Combined wit h nitrogen, sulphur and ot her elements to make proteins. starch glucose ● Respired to release energy t hat is needed for growt h and cell activities. seeds, e.g. peanuts, solution. ● Conver ted cashew into nuts lipids, and soya such as oils found in many beans. 36 835292 CSEC HSB Unit A Topic 3.indd 36 08/01/2015 15:58 Photosynthesis, food chains and food webs Photosynthesis enzymes, cell membranes nitrate from ions the soil proteins photosynthesis amino stored e.g. in peas stored seeds, and in respiration acids beans seeds glucose lipids as energy glucose store stored short cellulose in leaves term as energy starch sucrose store for use at night transported to stored cellulose fibres in cassava, cell in yams, potatoes as stems walls bolls and for in seed cotton long-term roots stored in stored A.3.1.10 The fate Photosynthesis Photosynt hesis contain strikes rst t he it step dioxide in molecules t he rest uses a is series not diffuses Chloroplasts The also of shows so in t hese t he photosynthesis chloroplasts, to it of This break is used and palisade which pigment water by to are green absorbs molecules released reactions cells cane structure Hydrogen leaf found of in chemical needed, are plant energy sugar. of out ar rangement whic h and products chlorophyll. t he making the place pigment and in takes of in beet sugar Figure store dispersal sugar p energy from make t he and spongy cells in leaves str ucture of a is single light apar t. water sugar. mitochondria into because t he This reacts in is t he wit h Oxygen t hey t hat carbon from respiration water and air. mesophyll shown in palisade Figure cells in leaves. A.3.1.12, mesophyll cell. p Figure A.3.1.11 adapted large they to surface are distance diffuse thin, for to Leaves absorb area so light of the cells is a a tissues; short dioxide that well having green there carbon are by to absorb it for photosynthesis 37 835292 CSEC HSB Unit A Topic 3.indd 37 08/01/2015 15:58 Photosynthesis, Photosynthesis food chains and food webs sunlight upper cuticle: waterproof layer that cuts down water also lost epidermis: cells with no goes straight single layer chloroplasts. of Light through the by palisade mesophyll: evaporation chloroplasts the palisade contain lots cells of chloroplasts. cell wall cytoplasm Most photosynthesis cell spongy occurs mesophyll: here membrane leaf more stem cells rounded with lots of vein: air spaces contains nucleolus between xylem vessels them that bring and salts leaf and water vacuole lower thick epidermis: cuticle. Has no lots to the nucleus phloem root of tiny holes tubes called stoma). t. (singular These gases to in p Figure A.3.1.12 chloroplasts, 0 The which arrangement are found in allow diffuse and of out cells palisade that take stoma guard stomata in a and plant palisade dissolved mesophyll cell food away carbon enables spongy cell it to mesophyll dioxide diffuses in photosynthesise efficiently; photosynthesis takes place inside cells Questions Key terms ! Mesophyll The between upper and the cells in the lower the tissues in a 1 Define the 2 Write 3 Identify term photosynthesis leaf out the word equation for photosynthesis. epidermis epidermis. mesophyll The the raw materials, source of energy and the products of have photosynthesis. many chloroplasts that carry out 4 What is the role of 5 Explain 6 a Why do leaves b Why do they chlorophyll in plants? photosynthesis. Stoma A epidermis diffusion dioxide small of of a hole leaf gases and that – oxygen the atmosphere the leaf. in the how leaves gain their light, carbon dioxide and water. allows have a large surface area? carbon – and have many small holes on the lower surfaces? between the air inside 38 835292 CSEC HSB Unit A Topic 3.indd 38 08/01/2015 15:58 Photosynthesis, A.3.2 Plants food chains and food webs Interdependence are impor tant microbes on are eaten by are called t he to Ear t h us and all because herbivores, of organisms ot her t hey whic h in Interdependence animals, make tur n food are and Learning most available eaten by of for By t he us. car nivores. Plants the because t hey photosynt hesise and be Producers are and t he also for indirect all t he source of parasites food and for car nivores t hat shows show two feeding different relationships food chains. by The means arrows of food show chains. t he Figure energy direction in which ows. .. .. .. long-horned you ways in which depend plants either directly indirectly chain draw food and ● the food webs grass the organisms explain A.3.2.1 ● t he topic to: eat ● can this decomposers. or We of able explain on herbivores, outcomes provide other food. organisms Plants ● producers end should of chains from broad-winged both aquatic identify trophic in a a food terrestrial (marine habitats the of and freshwater) organisms lizard principles and levels food of chain. hawk grasshopper .. mangrove shrimp tree great blue p heron p Figure A.3.2.1 T wo examples of a food chain Figure 0 A.3.2.2 Key A mangrove forest terms ! Herbivores are primary second ary consumers. consumers In t he rst and food animals chain in t hat feed Figure on t hem A.3.2.1, t he are broad- Producer its winged heron hawk is a is a terti ary secondar y consumer, in t he second chain t he great own food chain may have t hree, Primary four, ve or more trophic organism by that makes photosynthesis. blue consumer. that Each An food consumer gains energy by An organism eating levels: producers. Secondary producer primary consumer secondary consumer organism There are leaves. plants many Ver y and few pr imar y consumer s animals feed animals are on t hat one feed type of on g rass food. and Animals on mang rove t hat eat bot h omnivores eating better way to show to draw t he feeding relationships in a community is a food web . Figure A.3.2.4 shows a in a forest in by consumers. energy by An organism eating consumers. of simplified level Feeding level in a food food web An energy consumer gains Trophic organisms gains primary T ertiary that that secondary A consumer tertiary consumer chain. Producers, consumers Dominica. and decomposers trophic are examples of levels. Food chain show feeding organism at A simple way relationships each trophic to with one level. 39 835292 CSEC HSB Unit A Topic 3.indd 39 08/01/2015 15:58 Interdependence of Photosynthesis, organisms barn antilles p Figure A.3.2.3 Herbivory in racer food chains and food webs owl (snake) action mangrove cuckoo Dominican 0 anole (lizard) common Study ✔ bat caterpillars Many are fruit tip producers microscopic in aquatic algae. habitats Some grow bush-crickets on rocks or suspended the on in coral, the many water are forming phytoplankton. grass p Figure A.3.2.4 organisms Many such fungi insects. As released. water aquatic Phytoplankton habitat from (×100) Decomposers and fall and suppor t reef. some of the litter break organic become also root and matter break ions, also down on for Decomposers soil roots food webs provide food for ground. between and which (see Decomposers, in t he soil ear t hworms organic ions but in rest food trees t hey do turn of web t he and not are t hat is secondar y rst eat eaten food algae are matter, absorb Figure to dark- and soil mineral magnesium ions t hem A.2.2.10, all by of t hem. small are along page wit h 26). into small Bacteria animals, and which e.g. mangrove pieces fungi by crabs feed provide on food to web. suppor ted live consumers, shredded on t he by ver y coral, small absorb on Bacteria dead and and fungi Here are are grazed t hree by sea food urchins chains for and coral sh like organisms sunlight is and t he coral produce food. decaying Algae growing on coral reefs Phytoplankton web A more show feeding many organisms. complex relationships way to between Phytoplankton of A food web is many food chains. - - - parrotsh zooplankton coral parrotsh. reefs. matter. composed relationships matter suppor ts plants, t heir t he organic phosphate available hairs under down and t he Microscopic They Food feeding trees terms ! feed leaf nitrate chains t hey t he Anot her that in This shows forest Dominica bacteria, t he from shrimps, t hem 0 web fruits, an leaves Key as These food in decomposers such t hrough Aquatic A.3.2.5 live and t he food forest humus. nutrients Figure This a organisms as coloured p in leaves, coral buttery sh moray eel parrotsh octopus moray eel dolphin 40 835292 CSEC HSB Unit A Topic 3.indd 40 08/01/2015 15:58 Photosynthesis, food chains and food webs Interdependence of organisms Figure A.3.2.7 shows a food web for a coral reef, showing how the feeding relationships are more complex than shown in the three food chains opposite. sun phytoplankton zooplankton p Figure sea from coral A.3.2.6 the many These are urchins surface of these long-spined grazing of sea a the algae coral reef; when urchins died off anemone around Jamaica the algae grew, jellyfish overshadowing the coral which died parrotfish crab 0 butterflyfish sea turtle Talk about ? The complex Discuss these friends, family web of life questions and with teachers. your Y ou octopus may nd webs ● that will How drawing help are the the organisms some food discussion. following marine dependent on each shark other: p Figure A.3.2.7 Part of a food web for a Caribbean coral algae, phytoplankton, zooplankton, reef parrotsh, crabs, coral, sharks, shrimps, sea sea urchins, birds, lobsters and turtles? carnivorous ● fish What are the long-term consequences water if shermen take beetles too many of the edible species? tadpoles small fish i water fleas mosquito larvae freshwater mussels green p Figure A.3.2.8 Part of a algae food web for a freshwater pool 41 835292 CSEC HSB Unit A Topic 3.indd 41 08/01/2015 15:58 Interdependence of Photosynthesis, organisms We are dependent indirectly. chemical plant 0 for our food Photosynt hesis energy material, in plants. If we from plants. The on t he compounds e.g. from is cereals eat sh process or or plants process t hat beans, meat, t hat animals t hat make t hen t hen star ts and we plant are are light tissues. getting getting ever yt hing chains is and directly conver ts up we food food and energy When our into we energy energy webs eat directly indirectly photosynt hesis. Questions Exam ✔ tip 1 When drawing food chains or Believe These webs point The make from the arrows energy sure that food show the to the it or not there are animals that feed on long-spined sea urchins. food are crabs, starfish, porcupine fish and wrasse. arrows the way feeder. a Draw a food b State the chain that includes sea urchins. the trophic levels of each of the organisms in the food chain. ows. 2 Referring the 3 to trophic Refer two to level Figures freshwater each A.3.2.4, Figure of each two terrestrial food chains indicating organism. A.3.2.7 food draw and chains. A.3.2.8 to In case each draw two marine indicate the food chains trophic level and of organism. Summary Photosynthesis, ● ● Photosynthesis The site The source artificial ● Plants many are into energy The walls Plants is of webs light energy chloroplasts photosynthesis materials such to as for and are in is transport also to either which energy sulphur – chemical are cellulose the amino to or water. converted throughout converted sunlight and storage, make energy. cells. dioxide sugars, for into plant light carbon make sucrose Sugars are starch nitrogen proteins. are producers and nutrients provide food herbivores that herbivores, or same lipids into for plant. acids that Sugars that are are stored are eat as they for themselves for many them, responsible living indirectly decomposers both are herbivores and for for organisms, if they on are that feed and carnivores, producing animals and either directly carnivores dead animals so also food if that and rely to supply decomposers. on they eat are live plants. plants Many in the ways. food more chain shows organisms interconnecting the for and food conversion raw with and energy. Plants A the photosynthesis cell humans ● of light. use energy ● is chains photosynthesis combined made for of compounds, making ● food feeding freshwater at the feeding different food chains relationships in relationships trophic and a is levels. a habitat, more such A between food web complete as a three way forest, or shows to coral many show reef or pool. 42 835292 CSEC HSB Unit A Topic 3.indd 42 08/01/2015 15:58 Photosynthesis, food chains and food webs Practice 8 Practice Section 1 Chloroplasts in a palisade mesophyll cell are Questions in t he Questions A vacuole B nucleus C cytoplasm D between A Which best describes t he process known as t he cell membrane and t he cell wall photosynt hesis? 9 A The uptake of water by t he roots of A student He B 2 Transpor t of C Absor ption D The Which use of of t he sugar of in t he carbon light dioxide energy following phloem is to by make t he gas of t hen t he starch. Which oxygen nitrogen C carbon hydrogen A Which of leaves The a 4 lion B rabbit C cabbage D human Which and used B in being absorbs t he producer B consumer C carnivore D decomposer is of a week. t hem his results and conclusions? for stained brown indicating that the The stained leaves leaves The all with all t hat stored iodine t he with stored black starch solution plant iodine starch wit h had had had iodine made been used up. solution been used up. solution glucose and starch. leaves stained t hat brown t he plant wit h had iodine made solution glucose and Which of starch. t he following are t he raw materials for photosynt hesis? A leaves for producer? 10 organism What describes The digests dead organic matter A Sunlight B Water and carbon t he and oxygen C Water and sunlight D Carbon dioxide externally products? Section 1 A term for t he green pigment found in dioxide and oxygen B student used investigate 5 dark tested black stored A t he and the D is in leaves that stored following t he stained dioxide t he plant of indicating indicating 3 two leaves. indicating D potted food. C B a removed plants. photosynt hesis? A kept plants. t he t he apparatus effect of shown different in light t he diagram intensities to on t he t he rate of photosynt hesis of a pond plant. The student plants? monitored A vacuole B chlorophyll C mesophyll D stomata t he investigation. gas room The temperature table shows t hroughout t he student’s t he results. collects glass tank here with water test-tube 6 In a food chain, which provides energy for secondar y consumers? pond A producers B sunlight C ter tiar y D primar y plant consumers consumers syringe 0 7 The diagram shows t he trophic levels in a food chain. scale / mm 10 Producers Primar y consumers consumers Ter tiar y Which level trophic Secondar y 20 consumers has t he most energy? 30 air A Producers B Primar y bubble 40 in movement of capillary consumers air bubble tube 50 movable C Secondar y D Ter tiar y consumers 60 lamp consumers 70 80 ruler -I-~_'__'_'_'__________________ 43 835292 CSEC HSB Unit A Topic 3.indd 43 08/01/2015 15:58 Practice Photosynthesis, Questions 3 Distance lamp of from Distance pond by air travelled bubble Rate in a A student investigated a food local chains habitat and and food webs found four of photosynthesis/ organisms feeding organisms are: at different trophic levels. The −1 plant/mm 5 minutes/mm 20 mm min 30 long-horned 6.0 i) 30 26 5.2 40 14 2.8 ii) 50 7 60 3 t he chain. [2] Indicate of b 0.6 In one i) Describe how apparatus ii) State why to t he obtain gas is investigation. iii) State why tubing. b i) ii) c t he Draw Explain t he a t he t hese produced would use results. during in t he c t he The bubble moves down Sea t he grass t he rate graph of results. of photosynt hesis t he Sea results. The products a i) ii) of Write tur tles, [4] photosynt hesis a word Describe are equation how for sugar and b Describe c Explain cell. photosynthesis. photosynt hesis t he fate photosynt hesis. process why to all if passage in a found t he no to t he lizard hawk food trophic level grasshoppers. t he ot her grasshoppers are of describes marine provides food grow algae eaten organisms were food for sea t he which by and chains t he feeding habitat. on parrotfish. parrotfish two chain a [4] happen all make urchins sea are puffer and grass grazed fish. Humans tur tles. including by parrotfish. Groupers catch and are eat groupers. to show t he feeding oxygen. occurs wit hin relationships given organisms each in t he passage. Use different [2] in food chain. [2] a d leaf chain organisms predators [5] food anolis to [4] urchins Draw 2 student photosynt hetic missing [1] your would following Many table. food relationships [1] air t he on grass organisms organism. t he what removed. [3] [1] Calculate from student each area Suggest a grasshopper Arrange Using only likely effect information in t he passage describe t his marine habitat. t he [5] of t he sugar made of humans on [3] during [5] photosynt hesis living t hings. is a ver y impor tant [3] 44 835292 CSEC HSB Unit A Topic 3.indd 44 08/01/2015 15:58 Unit A Energy ow and cycles A.4 A.4.1 Energy through an ecosystem Learning By Energy ow and the end principal source of energy for life on Ear t h is t he Sun. and use it The Sun’s made available by producers t hat absorb it to make be sugars conver ted into a explain wide range of ot her up of the the Sun’s energy atmosphere, the never soil or reaches the producers oceans. Many (plants). Instead terrestrial it warms ecosystems, why in almost Figure all of A.4.1.3, the Sun’s are too inhospitable energy that falls ● to here support is wasted much as far plant as life, each concerned. explain so ● how As you producers However, in some is can of not see in t he photosynt hesis to used Figure Sun’s make by a energy A.4.1.2, much of the level energy trophic each explain is used what level is shown by photosynthesis energy of numbers that and reaches is available trophic pyramids is there in like at that you compounds. at Most topic to: t hat reduction are this able energy ● is of loss should The outcomes biomass. them. energy reaches carbohydrates producers and ot her and is used organic by t hem molecules. 'I' energy is available not for photosynthesis its wavelength not suitable absorption if is for by chlorophyll approximately energy 400 000 kJ from the Sun of radiant falls on 2 1 energy is m of the plants each year not around available 1% of the energy of for sunlight falling on the plant photosynthesis is if light is absorbed and from the by chlorophyll reflected used for photosynthesis plants’ surfaces p energy is not available for Figure light passes through the Figure A.4.1.2 producers Very (green little of the energy available if we Is only it better eat plant for the foods and leaf give p A.4.1.1 photosynthesis planet when from the Sun is absorbed up more by eating food for meat? Would there be everyone? plants) t Figure A.4.1.3 Most Earth’s surface is by water; surface much is fairly of the covered of the land barren like this 0 ✔ Study The area of tundra in north kilojoule does much not plant Caribbean support life as (kJ) is the unit for Norway energy. that tip There are 1000 Joules as land in the in one kilojoule. 10 000 alive. unit, kJ every You day Remember kJ, gures when for to you energy need to use write ow about stay the any or energy consumption. 45 835292 CSEC HSB Unit A Topic 4.indd 45 08/01/2015 16:00 Energy through an Energy ecosystem Energy has have is not Some of to products of t he t heir par ts end to any t he energy wit hin t he t hat plants biological up to being organisms. passes plants level photosynt hesis ot her energy of trophic may happens energy available t hat one what chemical have and absorbed molecules t hat cycles and t hey made. Some so ow become ow are to respired respired shed by t heir t he plants, leaves and so t his t hey is die decomposers. eaten anot her. are Plants by herbivores The by energy t he so t he energy herbivores herbivores, get passing has from to moved eating carnivores from plants or to decomposers. respiration – 1025 production urine 37 and faeces 1900 consumed 3050 0 Exam ✔ Energy ows through tip in one direction ecosystems, it does not p cycle. Energy is never Figure A.4.1.4 Energy flow through a herbivore (primary consumer) in kJ recycled. 2 per When you eat respiration food and you much use it lost as is year your surroundings. You it back to the plants heat as does are not a beacon of not farm. cycle The round transfer an of ecosystem energy of t he energy trapped by t he trophic levels plants t he ot her is also •- 1-~~ --.....•• • input during from the as a forest, producers to coral reef herbivores or is in photosynt hesis. The about transfer light! between energy such from light. 10% You grassland don’t livestock give of 1 m in Energy to for about 10%. Sun photosynthesis energy in lost energy respiration in lost respiration 10% lost Herbivores excretion energy respiration 10% ---+ Producers energy in in 10% Carnivores excretion and defecation Top and death + + carnivores excretion and energy defecation death lost respiration lost defecation in death respiration death Decomposition p Figure A.4.1.5 energy is ‘lost’ The as a flow of result energy of through respiration, an ecosystem; incomplete As you move energy When all of goes that t he all the animals, along grow in farmers such crops, t he as or barley food and such food grow, energy is the is as chain, rice plant maize, producers digestion ‘lost’ less in into the consumers – excretion energy yam for to us as food to feed or goes and is available because respiration. and available buy, or in incomplete t he decomposers energy cereals, not by fur t her to farmers Livestock buy note consumption t hey human primar y may t heir grow consumption, consumers. animals. fodder They crops, may such as 46 835292 CSEC HSB Unit A Topic 4.indd 46 08/01/2015 16:00 Energy grass, and ow and alfalfa cycles and chickens, Energy clover, use up for animals much of t he to graze. energy in Animals, t he food such t hat as t he pigs, cattle farmer gives 0 Talk through an ecosystem about ? t hem. This available A means to us vegetar ian of links in as t he diet t he t hat of t he secondar y can food little suppor t chain energy in t he plant food t hat t hey eat is Energy consumer. far more more people. individuals at If we t he cut end down of t he t he number food chain Discuss friends, may can be fed. energy This t hat consumers is because occurs we between are t he cutting down producers t he (crop 90% plants) ‘wastage’ and of many meat is in plant many people from have may animal a poultr y, increasing. diet countr ies wit h If have some are to to have or diet lamb, c hange to meat var ied sh, far mer s to tend sh. t hat beef In t hat t he includes and provide one diets t hat mainly more a pork . enough includes food more for of that and with your teachers. drawing Y ou some diagrams might We do help the discussion. could if we a lot all to save became the vegetarians. food of population ever yone, plant statement chains countr ies propor tion human food of consist developed higher The in secondar y (humans). or igin this family nd planet People losses our foods and less of Sun’s foods. Questions 1 Use Figures energy that A.4.1.2 and reaches A.4.1.3 Earth is to explain made why available to very little food the webs. p Figure these 2 Explain why all the producers than all the tertiary in an ecosystem much receive 3 What the percentage next trophic Ecological Diagrams t he way Pyramids Imagine cattle t hen t he a ot her eaten farm number by will of that enters same a we draw number we of energy pyramids moves self-sustained animals, t he be people much animals might pyramid each a such who greater will diagram draw of are a t hrough of ten farm, as be like on t han t he t he much represent somet hing level to A.4.1.8 trophic level is available of convenient met hod of showing t hat in pigs farm. of A.4.1.7 goats, The number greater Figure and are in which number animals. t han t he reared of tree In turn, t hat much of it? number of on t he people. p Figure is of t he It t he like number t he chain it number t he Figure shows food t he and A.4.1.8, numbers in t his represents pyramid-shaped. of number However, of of t his is an The trophic is not of numbers. Figure A.4.1.9 shows a pyramid of t hat suppor ts large numbers of herbivores each t he at bar case numbers and a t he producer and herbivore trophic levels form few an mixed farm a is level. always of small t he organisms widt h A (people) example individual each (plants), carnivores which farm. at producers A.4.1.7 Cuba 0 for Key term ! Pyramids of that the shows numbers numbers A of diagram organisms wit h each trophic level in an ecosystem. a size of each block represents the individual organisms at carnivores. numbers Note waste and plants The single to to at pyramids give for ecosystems. chicken, live (animals) numbers. propor tional Figure to herbivores trophic to energy ecosystem. in If afford numbers small, and energy the we food level? ecological which of the in Can this pyramids called in of consumers all more them energy A.4.1.6 cows of inver ted each trophic level. pyramid. 47 835292 CSEC HSB Unit A Topic 4.indd 47 08/01/2015 16:00 Energy Trophic through an Energy ecosystem ow and cycles levels carnivores secondary consumers small birds herbivores primary consumers F \ caterpillars plants producers oak p Figure A.4.1.8 A pyramid of numbers for an imaginary farm Pyramids A 0 second bioma ss Key terms known ! into Biomass an The biological organism. This sor t a Figure A.4.1.9 An inverted pyramid of numbers biomass (i.e. as of ecological dr y mass pyramid account t he of of fact pyramid living biomass. t hat is constr ucted mater ial) This, organisms at eac h unlike var y a by showing trophic pyramid g reatly in of size. t he level. This is numbers, Pyramids takes of material biomass in of p tree excludes are hardly ever inver ted. This is because it takes many kilog rams the of plants to to suppor t suppor t 1 kg of herbivores and many kilog rams of herbivores water. Pyramid that of shows organisms biomass the at A biomass each 1 kg of car nivores. diagram The of trophic level typical four in shape trophic of levels a is pyramid shown in of biomass Figure in a A.4.1.10. food The chain units or for food each web level wit h of a 2 an ecosystem. pyramid Trophic of biomass are mass per unit e.g. kg per m levels 2nd tertiary area, level carnivores consumers 1st secondary level carnivores consumers herbivores primary consumers plants producers p Figure A.4.1.10 ecosystem Pyramids Pyramids of of ecosystem Trophic with A typical four of biomass in an levels energy numbers at pyramid trophic a and moment in pyramids time. A of biomass pyramid of a snapshot of energy, give however, is an levels determined carnivores secondary 4 energy herbivores primary over a period of time. This is because it shows t he rate at which consumers ows or is in Figure t hrough estimated for a a trophic whole level. year. An This is example determined of a for pyramid a of day or energy a is week, given consumers 24 plants producers 4925 Unlike can p A.4.1.1 1. Figure A.4.1.11 A pyramid of pyramids never be arctic tundra on Devon Island per the figures are in kJ per m energy get all t hrough Indeed, year inver ted. To and pyramids understand why, of biomass, look again pyramids at Figure of energy t heir energy from t he producers. Therefore, A.4.1.5. t he ow The of in 2 Canada; numbers energy herbivores for of as t he herbivores producers use some cannot of t heir exceed t hat organic t hrough compounds t he in producers. respiration, 48 835292 CSEC HSB Unit A Topic 4.indd 48 08/01/2015 16:00 Energy while ow In cycles herbivores herbivores most any and is fail to eat signicantly pyramids one Carbon trophic of all energy, level t he less producers, t han 10%, reaches t he t he or t he energy less, of trophic t he level energy ow ow t hrough energy t hat above. For energy xed t hrough t he and nitrogen cycles t he producers. ows t hrough example, on A a typical and farm ot her ot her dead only plants animals leaves about in t hat to a 10% eld graze (at gets t hat decomposers most) eaten eld. and as by of t he t he Most heat cows, of t he chickens, remaining energy by from t he t he goats 90% plants is grass or lost to as t he atmosphere. B Questions 1 ‘Energy to 2 that is Match a a is up the c a heavily why predatory Suggest and 5 for 6 in (see your an as units of of such the eels in in Figure with of plants a the energy go C A.4.1.12 flies very and all A.4.1.5? on p a single horses Figure with flow recycling of lizard, which are herbivorous and fish to support a few sharks. levels of a pyramid of numbers a flow tundra carnivores ecosystem A.4.1.11). a the through Suggest pyramid of the like the what biomass in an ecosystem herbivores. one you for a on Devon might Island expect Caribbean if farm. and nitrogen cycles Learning By the end should provides life on Ear t h wit h a seemingly inexhaustible supply photosynt hesis. Life has existed on Ear t h for about 4 be and it is estimated it will last for anot her 1 billion years until t he too hot for life to this able topic you to: explain processes involved carbon is recycled Sun ● becomes of billion when years outcomes of ● for different answer. Global energy Three numbers ticks. of through energy Figure Carbon Sun of biomass. the A.4.2 The A.4.1.12 pyramids a numbers and few with which large grasshoppers as trophic does Figure numbers grassland kilograms moray where shown number numbers for So shown large of large many energy it area a as numbers parasites shows compared chains of large such than A.4.1.3 Explain a takes the less b with pyramid Canada you it fish, why be Figure with destroyed’. supporting quite suitable a Explain must feed, infested Explain food bush plants, field nor pyramids ladybirds and from rose individual 4 created ‘lost’ single few 3 not describe the recycling of the recycling of continue. carbon Recycling of energy environment is cannot impossible: be turned t he back heat into t hat light. all organisms Life will not lose to t heir continue ● describe if nitrogen t he elements t hat comprise living tissues are not recycled. There is no a continuous shower from space of carbon, nitrogen, oxygen and the uptake we have on Ear t h has to be enough, as t here is no external down by would has calculated decomposers ll up wit h of low would t hat t here and dead concentration t hat if recycled plants carbon be cellulose metres dioxide no as more in in plant carbon high. t he tissue dioxide Also, was t hat wit hin atmosphere t he 20 would not nitrate plants to proteins broken b decomposers c nitrifying d nitrogen-fixing world years fall by supply. form Someone of green hydrogen. ions What involving to t he levels bacteria so bacteria. photosynt hesis. 49 835292 CSEC HSB Unit A Topic 4.indd 49 08/01/2015 16:00 Carbon and nitrogen Energy cycles A similar ‘element crisis’ naturally decient in growt h ver y is consumers The slow. and so carbon would nitrogen. The t here occur The impact are of ver y wit h soil t his few of nitrogen. contains is t hat Some few t here little and cycles ecosystems nitrate is ow ions and energy to are plant pass to t hem. cycle The element carbon (C) is found in all organic molecules. The carbon cycle illustrated in Figure A.4.2.2 shows how carbon atoms are continuously taken up, converted into compounds and then recycled. Carbon atoms may remain in some places in the cycle for thousands or millions of years. Think of the carbon atoms in human bodies preser ved for a thousand years in the peat in Denmark or the coal that has been in the ground for 300 million years. p Figure in the A.4.2.1 carbon happening How cycle many can stages you see here? carbon in respiration dioxide the air produces photosynthesis carbon 0 dioxide as uses it Key releases carbon to ! from Organic molecules based on the element examples are carbohydrates, dioxide energy terms make food food Molecules eaten carbon; by fungi animals respire proteins and fats. bacteria Carbon cycle The element respire carbon is present in all living decay organisms. It’ s recycled dead various processes, of through which animals human are of described in the carbon cycle. decay dead Fossil the fuels dead Fuels and formed fossilised oforganisms; extraction fossil fuels of plants from fossil fuels remains examples are coal, fossilisation oil and gas. p Figure Look A.4.2.2 carefully following ● The at carbon Figure cycle A.4.2.2 of t he carbon cycle and note t he points. Carbon dioxide oceans) by is taken from photosynt hesis in t he atmosphere plants, algae and and from some water (e.g. lakes, photosynt hetic bacteria. ● Carbon dioxide is added to the atmosphere and to water by respiration, which occurs in all organisms. ● Carbon dioxide is added to the atmosphere by the combustion of wood and fossil fuels p Figure A.4.2.3 Peat vegetation that properly. is It forms does carbon not from decompose sink that ● Carbon food up carbon for many years going carbon dug back in to the dioxide. In some out and burnt as chains from such plants as to carbohydrates, herbivores and fats t hen and to proteins, pass along carnivores. preventing ● it compounds, locks atmosphere places it as is Plants and fuel. lose faeces. matter, ● Some in leaves and release carbon carbon carbon and die; Decomposers carbon compounds sinks, animals feed e.g. compounds in are not bogs. fossil pass dead dioxide peat form on by out and t heir waste products decaying plant in t heir and urine animal respiration. decomposed; Eventually instead t hese t hey accumulate undecomposed fuels. 50 835292 CSEC HSB Unit A Topic 4.indd 50 08/01/2015 16:00 Energy Trace ● ow and around cycles t he Carbon carbon Carbon atoms can tropical forests be cycle to nd recycled where examples ver y conditions quickly are ver y of – t he t his following. happens favourable for in 0 Did a dead leaf is broken down in Carbon atoms dioxide ● in Carbon being pass t he t hrough atmosphere atoms remain released into in t he four and some decomposers so ‘sinks’ organisms back on t heir way from carbon reducing carbon that become again. years ago Case The The effect last fossil still of 150 fuels years compounds and increase in t he in energy is Sea ● ● have of for a ver y long time A sink of of in the carbon before the size atmosphere 350 in England in 2014 in was Central Congo Africa. million Some of t he Over and concentration ‘locked of t he from in same past 50 – may Antarctic get has atmosphere especially t hat years t he heat Ear t h’s Alt hough consequences and far of in greenhouse way 0.5 °C. and wood. t he t he atmosphere t he in of burning regions up’ dioxide about following t he temperate t he by cycle result results much apparent Arctic in Ear t h’s in in t he carbon This t he rise carbon warmer t he become in areas been low-lying of of t his climate worse. melted. countries (e.g. Guyana) and coastal Bangladesh). are are killed in changing, have and oods and tens of t housands making droughts and famine should becoming Lovelock is as in and abundance, rarer t hat concentration renewable adapt such increasing hurricanes typhoons. most worr yingly pests crops. are dioxide change changes, storms, recommended more James more are of species carbon climate in carbon is bot h of energy much, in patterns diseases scientist trees, change. gases the likely. species of massive fuels. This greenhouse. people Some risk otherwise dioxide homeless. have we might rising. There fuels of become ooding Scientists in a large (e.g. more ● by land and t he signicant amount heat Increased Rainfall ● trap ice a on concentration already are seen climate ver y t he levels made ● fossil activity t he probably Hundreds ● – sound Some ● in from atmosphere. various trapped has not change ● up’ burning t he to which dioxide climate t he reducing carbon may absorbed ‘locked have in contributing effect important atmosphere. were human dioxide tropics, This is are t hat very holding study carbon t he atoms are and atmosphere. Brazzaville Carbon know? carbon discovered ● cycles days. for ● nitrogen ? humid Carbon t hat you and has to t hese coastal and t he of argued happening extinct. steps in sources or taken to atmosphere energy t hat we are instead. humans cannot changes and make and moving by it. resources people t he using The should reverse defences stop increase less fossil independent accept Instead, available away t hat he says, for from t hese areas at ooding. 51 835292 CSEC HSB Unit A Topic 4.indd 51 08/01/2015 16:00 Carbon and nitrogen Energy cycles ow and cycles Questions 1 State and explain concentration a t he b an c t he burning increase change renewable 2 Suggest rat her 0 The Key of some t han what carbon of in fossil t he from steps of in t he t he following has on t he atmosphere: fuels; of using of t hat to each dioxide rate sources tr ying nitrogen effect photosynt hesis fossil fuels in of power plants; stations to t he use of energy. we can reverse take to adapt to climate change it. cycle term ! In just the same way that carbon has to be recycled for life to continue, so it is with Nitrogen An element needed nitrogen. This element (N) is found in many organic molecules, for particularly proteins and nucleic acids (DNA and RNA). Although almost healthy plant growth, plant roots ions. Chemical supply in the nitrate taken form of fertilisers up by nitrate 80% of the air is made up of nitrogen gas (N ), most organisms cannot make 2 use of it directly. This is because the two nitrogen atoms are bonded together often ions. ver y rmly and it takes much energy to break them apart so that nitrogen can combine with atoms of other elements, e.g. hydrogen, oxygen and carbon. Q __ ✔ Study Look very version carefully of the A.4.2.5 about nitrogen chain. Notice involved at the nitrogen Figure are Nitrogen along the and as cycle read along that rst Nitrogen t hat combined and here we the the in as a nitrate section to make food microorganisms nitrifying decomposers is will ion follow in protein. t he plant t he nitrogen onto chain t he soil Some t he of soil. wit h t he by a t his Here compounds t hese journey in peanut protein t here t he are leaf elements of a is nitrogen plant. will The be in called atom plant leaves decomposers to release ‘xed af ter uses t hat t hat it t he die will ammonia, nitrogen’ is absorbed nitrate and break which fall ions off down all becomes and ammonium as food tip ions in t he soil water. bacteria. Nitrication 0 There Key terms ! ions Nitrication The are process in to ammonium ions Nitrifying by are bacteria nitrite ions. in ions This t he is a converted wit h t hese ver y nitrif ying t hat gain t heir and specialist energy ot hers way of by by oxidising oxidising life, but nitrite many bacteri a. Plants are able to soils absorb are nitrate to as t heir source of nitrogen and it is not toxic to t hem. Plants t hen bacteria. bacteria Bacteria uptake that the convert soil (nitrication) which ions ions to nitrate teeming nitrate some ammonia ammonium ions to by roots proteins nitrate nitrate ions in in soil ions. plants nitrifying bacteria death nitrite ions in soil dead nitrifying (or ammonium ions p Figure in bodies bacteria parts , e.g. dead leaves) decomposers soil A.4.2.5 The cycling of ‘fixed’ nitrogen through plants, animals and bacteria 52 835292 CSEC HSB Unit A Topic 4.indd 52 08/01/2015 16:00 Energy use ow t he and energy cycles t hey photosynt hesis now But come t hat is Imagine peanut, more are absorb into full circle not t he eating digest protein broken a it as end and t he of light nitrogen t he stor y make need, to conver t compounds, which t hen you by from nitrogen peanut, t han down Carbon is atom as a your t hen decomposers been are source own you to has peanuts good sugars grown of produced proteins. We and fungi use t he nitrogen in for protein. If t he nitrogen human food. You t he eat peanut gives compounds. you These ammonia. compounds like protein as sources Figure and but turn includes it before to t hey can ammonia. animals in respire Now Figure t hem look at t hey t he have to expanded remove nitrogen t he A.4.2.6 Fish are rich in protein; of some energy, cycles have p Bacteria nitrogen recycled. proteins. excrete give t he especially and of the nitrogen in the proteins will pass its fish nitrogen cycle t hat the nitrogen on way through cycle A.4.2.7 . absorption proteins nitrate ions in in feeding proteins and in soil plants nitrifying animals digestion bacteria death death nitrite ions in soil excretion and egestion dead nitrifying bodies bacteria decomposers ammonium ions in soil wastes decomposers p Figure A.4.2.7 Nitrogen There are some ‘xed wit h nitrogen nitrogen’. It is is compounds. organisms, break organisms nitrogen once useful nitrogen cycle from Figure A.4.2.5 with the addition of animals xation combine t hat The t he xing t hat ot her combined nitrogen Unlike nitrogen molecules can of break elements wit h t hat is molecules ( nitrogen t hese now xed photosynt hesis, is for t he few ot her so of nitrogen xation). elements it which specialist is is used it bacteria is to carried apar t and 0 Remember make out t hat by are many Nitrogen many which able into to nitrogen. Nitrogen-xing bacteria Key terms ! called xation bacteria The convert ammonium in gas ions. Denitrication The which are nitrate process nitrogen ions process in converted to live in the root nodules of plants known as nitrogen gas (N ). 2 legumes, such as peanut, soya beans and pigeon peas, as well as many trees like Poinciana. They are important because they supply a source of nitrogen compounds to the plant. These are used by the plants to make proteins. Some nitrogen-xing bacteria live not in root nodules, but free in the soil. These add nitrogen compounds to the soil, increasing the nitrate ions available to plants. Nitrogen is also xed during t hunderstorms. Lightning causes 0 Did oxygen to react toget her at high temperatures wit h t he formation you oxides t hat form nitrate ions in t he ever had to change of nappies nitrogen know? nitrogen Have and you ? soil. a smell that (diapers) of and ammonia? bacteria have detected It is been likely breaking Denitrication down nitrogen baby’s Denitrifying in Trinidad conditions bacteria and of t he ver y live in Zapata low water-logged wetlands oxygen in soils, Cuba. such These concentrations by as t he Nariva bacteria conver ting compounds in the urine. swamp sur vive nitrate in ions to 53 835292 CSEC HSB Unit A Topic 4.indd 53 08/01/2015 16:00 Carbon and nitrogen Energy cycles ow and cycles ' nitrogen gas materials in (denitrication) t he soil. This as t heir balances t he way of releasing loss of nitrogen energy gas by from organic nitrogen xation. So, to we can give an add some almost more stages complete nitrogen (N to our nitrogen 2 ) nitrogen cycle in cycle Figure - ~ Figure A.4.2.7 . I in atmosphere ~ from A.4.2.8. lightning I- animal fertilisers plant nitrogen nitrogen compounds compounds nitrogen fixation absorption by death; plants wastes denitrifiers nitrogen-fixing bacteria root dead in nodules matter nitrate ions the in soil decomposers nitrifying decomposition bacteria nitrogen ammonium in p Figure A.4.2.8 The nitrogen Humans t he use t his nitrogen cycle in many fer tilisers to provide compounds. Nitrogen as process. t he Haber nitrogen soil cycle inuence of the fixation ions from This t he air is produces ways. One crops xed by of wit h t he ammonia, t he most nitrate or chemical which is signicant ammonium process used is to known make t he fer tilisers. t Figure A.4.2.10 These stem swellings ground are level root on the root nodules full of bacteria root root nodule contains hair – the nitrogen-fixing bacterium Rhizobium u p Figure A.4.2.9 A legume plant Figure root root A.4.2.11 These with nodules have nodules been show are cut open that pink the where nitrogen-fixing are to insides most the bacteria active 54 835292 CSEC HSB Unit A Topic 4.indd 54 08/01/2015 16:00 Energy ow and The recycling The roles q T able of cycles of nitrogen t hese A.4.2.1 Carbon are Roles is ver y of microbes Microorganism Decomposers in and bacteria) the Break bacteria Table on t he actions of down Convert bacteria microbes. of nitrogen compounds acids to of nitrogen ammonium ammonium ions to such as proteins ions nitrite ions and then to ions Convert nitrate ions Convert nitrogen to nitrogen gas p Figure inside Nitrogen-xing bacteria, e.g. gas into ammonium ions, which are in nodules of legumes by legumes the to make A.4.2.12 the root The cells nodule are full used of Rhizobium cycles A.4.2.1. recycling amino nitrate Denitrifying in nitrogen Role (fungi and Nitrifying dependent summarised and nitrogen-fixing bacteria. This proteins is a photograph electron taken microscope using an (x1000) Questions 1 What are the advantages to farmers of growing legume crops, such as 0 Did you know? ? peanuts and pigeon peas? The 2 Which processes in the nitrogen cycle nitrogen take from the air manufacture requires convert it into fixed Which process nitrogen in the available to nitrogen cycle reduces the quantity of fixed which fuels What are the roles of fertilisers energy, generate organisms? of comes burnt fertiliser 4 lots most nitrogen? of 3 of and and decomposers nitrifying bacteria in in from power the the electricity factories fossil stations that need. to the This recycling use of fossil fuels adds to the nitrogen? environmental impact of fertilisers. Summary ● ● Energy flows through A chain shows food organisms in an ecosystems, how energy it is flows not 0 recycled. through a small number Talk ecosystem. Modern ● T rophic out ● levels are the photosynthesis feeding are consumers; carnivores Food webs show there is plant and usually levels producers; that more more each eat herbivore a food one eats that are relationships herbivore usually chain. herbivores herbivores feeding than in that more Green eat plants secondary than food feeds than on one plants are that carry primary consumers. chains each plant; do, much fuels. herbivores are to must have more than one predator and carnivores usually feed on than one prey change and ecosystems are those on land including woodland, in and mountainside. freshwater, such as Aquatic streams, habitats rivers, are lakes in and water and ponds, include habitats and What marine in the sea, such as coral reefs, open water and areas of them. lost to capture Most the of to the and only the next in at small energy dead trophic decomposers animals a surroundings decomposers our and planet ways: others, eat if we we less, waste farm sustainably less without each that as they heat leaves. level. at percentage higher consumer is is lost trophic trophic the convert when There Energy of light into chemical they respire very little at each levels, energy and is energy trophic which limits that passed left the land and destroying can to to we the do as impact consumers of farming to on environment? reaches energy level the environments. seagrass. the Plants great this up the those reduce ● too on grassland, aquatic beach causes using impact on with is species. polluting T errestrial fertilisers, more food ● is survive food and The environment of uses herbicides, pollution fossil as species farming pesticides, share usually about ? of be is Discuss to family this and with your friends, teachers. passed respiration number of level. 55 835292 CSEC HSB Unit A Topic 4.indd 55 08/01/2015 16:00 Carbon and nitrogen Energy cycles ● Pyramids trophic each ● the the reduction Earth, the ● during as ● gain organisms the mass numbers are sometimes in of each number energy trophic quantity carbon of and but are very never level the of to the at inverted large each organisms in at usually biomass inverted the chemical nitrogen. all cycles and as show next. elements These that are elements dioxide they carbohydrates returns that energy. In from absorb to of the atmosphere as and dead they and sugars fossil and release and they Carbon photosynthesis. atmosphere wood doing the for such breakdown so it is starch. when organisms fuels. Fungi decaying carbon decrease dioxide and material dioxide to respire and bacteria and the are respire it atmosphere well. Nitrogen nucleic ions is and proteins that are ions. an acids use digesting the in important (DNA them broken Nitrifying Most and to protein muscle ammonium ● as combustion decomposers to carbon dioxide the from individual show small limited such when make Carbon are of of and recycled. require to a numbers Pyramids energy is the biomass Pyramids trees. need, quantity used in there continually of producers with On Plants show Pyramids level. the case organisms ● numbers trophic because is of level. ow make and down by organisms into their They the nitrate compounds it to make release soil ions make absorb proteins. microbes in cannot in Plants using tissue. bacteria ions element RNA). for use their are as in proteins the feed proteins, products to for form on e.g. and of the nitrate plants, contractile containing decomposers responsible plant of Herbivores waste that are such nitrogen into nitrogen ammonium recycling of absorb. nitrogen (N ) gas in the atmosphere as 2 it is very unreactive. ammonium such as these ions so legumes. bacteria agriculture as that The and growing bacteria in organic respiring this balances nitrogen cells legume Denitrifying and Nitrogen-fixing bacteria becomes inside crops, root can available nodules such as them is an in oxygen-deficient materials. The nitrogen alternative release gas of soya survive the convert to other legumes beans, are applying soils nitrogen absorbed to by nitrogen by gas gas organisms, are packed important chemical using as a into fertilisers. nitrate waste nitrogen-fixing with in ions product bacteria. 56 835292 CSEC HSB Unit A Topic 4.indd 56 08/01/2015 16:00 Energy ow and cycles Practice 8 Practice Which of t he following organisms digest dead Questions organic Questions matter? Section 1 Which is t he A glucose B t he C plants main source of energy for life on Ear t h? 2 nitrifying C denitrifying D nitrogen-fixing bacteria bacteria bacteria A pyramid of biomass A t he organisms at B t he biomass C t he total number D t he total mass shows: each trophic Which returns carbon cycle? carbon A combustion B photosynt hesis dioxide to t he atmosphere in t he C respiration D combustion of organisms of of bacteria legume plants? organisms organisms in in a trophic a food food level chain chain. Which process in t he carbon cycle uses carbon dioxide? only and are A nitrogen-fixing B nitrifying C protein-fixing D denitrifying A respiration B deat h C photosynt hesis D feeding respiration found in t he root nodules of Section bacteria B bacteria The diagram below shows a simplified carbon cycle. bacteria bacteria Carbon in student each only Which A at only 1 4 level starch 10 3 fungi B Sun 9 D A A investigated a habitat and drew t his dioxide air diagram A to show some of t he D results. B C –2 Snake: 500 kJ m 1572 kJ m Carbon in animals Carbon in plants –2 Bird: –2 Berries: 2215 kJ m E What is represented by t he diagram? Dead A a pyramid of numbers animals B a pyramid of biomass C a pyramid of energy D a pyramid of organisms and plants F 5 Which of nitrogen t he following does not contain t he element Fossil A proteins B deoxyribonucleic C glucose D ammonia acid a (DNA) b Give t he i) Which is t he role of denitrifying To conver t protein to Name ammonium B To conver t nitrate To conver t ammonium ions to i) Identify to nitrate 7 conver t Which of t hrough A All t he a t he nitrogen gas following food chain energy is to labelled gives rise to A to F. [6] fossil examples ammonium statements t he two raw of fossil fuels. materials [2] needed D. for [2] Explain how t his process is impor tant to ot her ions. living To F gas. ii) D processes process ions. nitrogen ions t he [2] two process C of how bacteria? c A names Explain fuels. ii) 6 fuels (N)? about t hings. [3] ions. energy flow goes t he correct? conver ted by producers to consumers. B The C Producers available available D The energy capture to increases all t he with light the energy trophic t hat levels. is t hem. available energy decreases as t he trophic levels increase. 57 835292 CSEC HSB Unit A Topic 4.indd 57 08/01/2015 16:00 Unit B Nutrition B.1 Learning By the end B.1.1 outcomes of this topic Balanced diet you Diet should be able to: The ● explain what is meant by quantity refer red balanced describe to the major nutr ient their is a into state the functions and and state of the vitamins A, B t hat types you eat of food are t hat made of you eat is nutr ients . type of subst ance broad found g roups: in our food. macronutr ients We and divide micronutr ients. e.g. are fats, t he food proteins subst ances and t hat you carbohydrates. eat in relatively Micronutr ients large are , t he functions and food subst ances you eat in small quantities, e.g. vit amins and of the is impor tant and iron classify vitamins soluble or fat to eat a balanced d iet t hat relates to our needs. A balanced minerals diet calcium salts. main It sources ● different D mineral ● t he foods main 1 C of The sources amounts, sources diet . two Macronutr ients ● quality your nutrients nutr ients and as diet A ● and a in the as must include: diet water ● enough soluble. ● ● ● for essential amino acids, essential fatty water ● our fats bre to for from eaten balanced cor rect replace proper t he in – diet, from whic h of a good healt h. Too of t hese components is provided by macronutrients lost of minerals in urine, t he sweat, digestive breat h system and in faeces moving found anus. propor tions, is energy proteins and healt hy nutr ients in our fats water t he cor rect quantity from functioning to – proteins) vitamins t he mout h t he needs and acids, micronutrients ● If energy (carbohydrates, muc h, can in or t hese diet. t he too A components balanced r ight make diet propor tions up cont ains so t hat a t he we remain few, L e g u m s e o t a t o have e s e g d consequences. b e boy A who nurse shows cares for a symptoms food or on consult packets food of tables of by nutrition p e a s a n d n u st S t a lp e s published severe to e young B.1.1.1 is g Figure you nutritional information p diet malnutrition organisations. foods in much diet you is to quantities eat of F balanced appropriate A ensure r a to u eat way s t i easier t he each of t he groups, as described different F a t s food Caribbean Institute Food and (CFNI). dooF t he ensure slaerec study to sl am ina balanced a m or f way eat food. e c ir One nutrient s t heir a b in know n is each a t s a p t here rarely of a people much n how a Most a a n ser ious by a n d t he o il s ge Ve ta b le s Nutrition p Figure B.1.1.2 showing the A chart different from food the CFNI groups 58 835292 CSEC HSB Unit B Topic 1.indd 58 08/01/2015 16:02 Nutrition Figure of Balanced B.1.1.2 foods t hat shows t he belong to different each food group. groups Each along sector is a wit h some different examples size. This 0 Key diet terms ! demonstrates healt hy, t he relative balanced quantity of each food group required for a Nutrients diet. required Types Unlike of nutrients plants, we must have a supply of organic compounds in our food are large we require t he raw materials for growt h and repair as well as supplying diet. complex in that are Macronutrients compounds large quantities that in Micronutrients are the minerals sources and of Substances the to diet. provide in vitamins that we require in very energy. small quantities Balanced in diet the A diet. diet that Macronutrients provides Proteins the energy correct and nutrients in quantities. Food group foods that A group of different Proteins are molecules made of long chains of amino acids held together by provide the same peptide bonds (Figure B.1.1.4). Amino acids are made of the elements carbon, nutrients in roughly the same hydrogen, oxygen and nitrogen – some also contain sulphur. Proteins are proportions. either brous or globular. Fibrous proteins are straight, or spiral, chains of amino acids that are usually very strong. Keratin and collagen are two brous proteins. Keratin is in hair and skin; collagen is in organs all over the body including bones, muscles, tendons, ligaments, blood vessels and the skin. Globular proteins are found solution in is a in globular Enzymes Proteins protein. t hat are used in Proteins also are acids in into essential must be is used two In packed cells as in a into red growth of diet. considering t hat cells are and and energy. t heir are t he cells in water blood. to and are Haemoglobin transpor t oxygen. proteins. repair hormones There soluble in blood globular some source our of are for enzymes, protein proteins cytoplasm reactions inside cells, proteins. grouped ● t he It catalyse membranes digesting spherical t he We 20 and the formation (e.g. insulin) gain our different usefulness to us and amino types in t he acids of of antibodies. by amino diet, t hey are groups: amino acids obtained (EAAs), from t he which cannot be made by t he body so diet p ● non-essential amino acids, which can be made by t he body from Figure would amino acids and so need not be in t he B.1.1.3 What food items ot her diet. the you French needed for give this fries? a child What balanced as well nutrients as are diet? Most proteins contain most (or all) of the amino acids, so a varied diet is never decient in any of the EAAs. Good foods for providing proteins include lean meat, sh, eggs, cheese, pulses (peas, beans and lentils) and nuts. amino acids SAFETY Make sure that you always follow these simple safety rules when you are peptide working in the lab. Always follow the instructions given by your teacher/lecturer . protein 1 Never 2 Wear 3 Tie taste eye any chemicals protection when or foods to be tested. indicated. p long hair Figure make 4 When heating 5 When heating, never point 6 When heating, never look Wear B.1.1.4 Chains of amino acids back. eye chemicals, use a test water tubes down a bath at test whenever one up peptides and proteins possible. another. tube. protection. 59 835292 CSEC HSB Unit B Topic 1.indd 59 08/01/2015 16:02 Balanced Nutrition diet Practical T esting foods for Activity proteins using the biuret test Requirements ● test ● a test tubes ● a solution protein, foods ● tube of e.g. a 0.1M ● egg albumen p Figure carry B.1.1.5 out your This food is how you containing 0.1M ● protein rack copper sulphate sodium ● water hydroxide ● a solution ● eye solution dropping pipette protection should tests 3 1 Pour 2 cm volume of of the water egg albumen test into tube solution into test tube 1. Put the same 2. 3 2 cm of Add dilute copper and shake. 2 Add 3 4 A positive 5 Make result Record sodium hydroxide sulphate will suspensions described 6 dilute be or solution indicated solutions each to each a violet by of to various test test tube. tube drop by drop colour. foods and test these as above. your results in a table. Lipids There oils), and p Figure B.1.1.6 positive biuret test A for negative protein and with is waxes are the made which acids Figure B.1.1.7 triglyceride The are of sebum of t he B.1.1.7). each are solid t he lipid molecules produced at of There t hat gram most by t he is a t he lipid carbon, glycerol when t han room common elements molecule means for including skin) and triglycerides steroids (e.g. (fats and oestrogen ver y t hey ot her in hydrogen combines high are our ratio wit h of respired oils are and fatty hydrogen release Fats triglycerides and oxygen t hree t hey macronutrients. temperature; bodies are to in our and acid are in more are made liquid lipids, energy triglycerides t hat They molecules oxygen much diet. t hat at room temperatures. Triglycerides are used and to heat are deposited provide a insulation. under long-term They are t he store skin of modied and around delicate energy, protection to phospholipids form organs. from They knocks when one of triglyceride the p (e.g. up one (Figure ·---· variety cholesterol). when fatty wide Triglycerides a test glycerol a formation molecule (a of molecule a of fatty t hen acids used to is replaced make cell by a phosphate membranes, group. including These t he cell phospholipids surface are membrane, fat) nuclear envelope Food sources meat and vit amins on page and r ic h fish. t hat in These are cell organelles. lipids foods soluble are are in butter, also lipids. margar ine, impor t ant There is veget able because more t hey about oil, fatty cont ain t hese vit amins 65. 60 835292 CSEC HSB Unit B Topic 1.indd 60 08/01/2015 16:02 Nutrition Balanced Practical T esting foods for diet Activity lipids using the emulsion test Requirements ● ethanol ● oil ● test 1 Place (e.g. olive oil) tubes 5 drops of oil ● test ● water ● eye into test tube rack foods ● (such as seeds) protection tube 1. 3 2 Add 5 of cm ethanol. ethanol Some may into test remain tube 1 and undissolved shake at the to dissolve bottom of the the oil test in the tube. 3 3 Put 4 Pour 5 A 6 5 cm the white Cut up Seeds lipids of water test solution of ethanol emulsion is the some make to into foods good dissolve into 2. and oil positive small material and tube then to into result pieces test. pour for and Add into test tube fats 2. and oil. place into separate ethanol and wait test tubes of water 5 as test tubes. minutes for described any above. p 7 Record your results in a Figure B.1.1.8 A positive result for table. lipids Carbohydrates 0 using Did the emulsion you test know? ? Carbohydrates t he elements are t he carbon, sugars and hydrogen starches and in our diet. They oxygen. The ratio of are made hydrogen from There to acids. oxygen in carbohydrate molecules is 2:1. In proteins and fats t he ratio are different Some are types of saturated fatty and is are found mainly in animals. different. Others found are unsaturated mainly in and are plants. Monosaccharides The simplest such as carbohydrates glucose. disacchar ides. are a long single They branched sugar into taste, soluble transpor ts generate Food All t he ATP sources when Dis acchar ides Food and sources milk . All Benedict ’s ● body in in are be joined joined to for m chains. are blood; t hey it need used is reducing wit h complex in Benedict’s sugar s except and sugars) to galactose, glucose. ready for m by They source cells which are of t hat t hat consist sweet energy; require of are to glucose it to 1 12). include sugars disacc har ides a page single pairs polysacchar ides and absorbed (see monosaccharides are into as (or into Monosacchar ides fr uctose conver ted and disacc har ides and biscuits, will give cakes a and positive honey. red/brown reagent. provide include sucrose a cane give source (or a of beet) positive energy. sugar, test fr uit wit h reagent. Disaccharides a be can glucose, and t he boiled r ic h as water monosaccharides precipitate monosaccharides unbranched t hat rich also such in energy t he can or unit, absorbed are are Monosacchar ides chemical are bond made known up as of a two monosaccharides glycosidic joined toget her by bond. 61 835292 CSEC HSB Unit B Topic 1.indd 61 08/01/2015 16:02 Balanced Nutrition diet ● • • • •• Sucrose, monosaccharides lactose complex lactose ...... ● and sugars are Sucrose as Lactose is are bot h cane maltose also impor tant sugar is are soluble examples in par ts used as water of a t he of disaccharides. and sweet human to taste. These Sucrose and diet. sweetener. disaccharides ● ● Maltose used in t he (malt t he making carbohydrate sugar) is in milk. produced manufacture of by some t he foods breakdown as well as a of starch raw and material is for alcohol. polysaccharides Polysaccharides made p Figure B.1.1.9 (simple Monosaccharides sugars), ● sugars) (complex carbohydrates); and They polysaccharides note by chains of glycosidic many carbohydrates (poly) simple wit h sugar much units larger molecules (saccharides) joined bonds. are much are all insoluble in water. that ● longer Polysaccharides are made as energy storage compounds in plants than and shown long complex disaccharides (complex polysaccharides of toget her are animals. here ● As ● we saw in in make cellulose Food and t he A.3, sugar plants form sources of for rich store sugar glycogen, t heir in cell starch as which starch. is ver y Animals similar and to fungi starch. store Plants walls. include bread, pasta, potatoes, cassava yams. Practical T esting foods Sugars are occurs when for called Activity reducing reducing they give a sugars sugars positive using Benedict’s because result the with type solution of Benedict’s chemical solution reaction is known that as a reduction. Requirements ● test tubes ● Benedict’s ● test tube ● 1% glucose ● water ● test tube ● eye protection racks baths greater at than any temperature 70°C solution solution holders 3 1 Put 2 water cm of into test 1% glucose tube solution in test tube 1. Put 1 and the same volume of 2. 3 2 Add 3 Place 4 A 2 cm both positive glucose or 5 p Figure B.1.1.10 A negative result positive if you result look precipitate on the for carefully at the reducing you can bottom right of Benedict’s tubes result will be red-brown Make into is a a any solution of water colour green suspensions solution bath a test at change solution; with to a any foods by 2. temperature from high precipitate different tubes blue. A low concentration of the same mixing with above 70°C. concentration will give an of orange colour. water. Leave them and for a of a few minutes for any reducing sugars to dissolve in the water. sugars; see the the 6 T est them with Benedict’s All monosaccharides solution following the instructions above. tube reducing and all disaccharides apart from sucrose are sugars. 62 835292 CSEC HSB Unit B Topic 1.indd 62 08/01/2015 16:02 Nutrition Balanced Practical T esting foods for diet Activity non-reducing sugars using Benedict’s solution Requirements ● test tubes ● 0.1M hydrochloric ● test tube ● 0.1M sodium ● water ● Benedict’s ● 1% ● test tube ● eye protection be racks baths sucrose sucrose supplier, T o identify T est for boiling solution from not a cane (this should chemical acid hydroxide solution solution holders sugar) non-reducing sugars, two tests must be performed. 1 3 1 Put 2 cm 1% sucrose solution into test tube 1. 3 2 Add 2 cm 3 Place than 4 tube two Note Benedict’s 1 into a solution water bath to at a test tube 1. temperature above 70°C for colour change no longer minutes. that sucrose T est of the solution solution is stays blue. If contaminated there by is any reducing then the sugars. 2 3 1 Put 2 Add 2 3 Boil this 4 2 cm 1% drops sucrose of hydrochloric mixture Remove from solution for the 2–3 water into test tube 2. acid. minutes bath in using a water test bath tube of boiling holders. water. Cool the test tube 3 and neutralise with 1 cm dilute sodium hydroxide solution. 3 5 Add 6 Replace 7 A 2 cm of the positive red-brown Note: into By tube result with boiling glucose Benedict’s foods be seen dilute fructose, for boiling water by any bath. change in colour, e.g. orange or precipitate. Practical T esting the will a with and in solution. hydrochloric both of acid, which are the sucrose reducing is broken down sugars. Activity starch using iodine solution Requirements ● test tubes ● test tube ● spotting 1 Put ● rack iodine in iodide solution (iodine tile potassium ● 1% starch suspension solution) ● eye protection 3 2 cm volume 2 Add two tubes 3 A 1 of of a 1% starch into test or three and positive by the water of into test tube 1. Put the same 2. iodine in potassium iodide solution to test 2. result yellow drops suspension tube will be indicated by a blue-black colour, a negative result p Figure B.1.1.11 tile and iodine for starch Using solution a spotting to test foods colour. 63 835292 CSEC HSB Unit B Topic 1.indd 63 08/01/2015 16:02 Balanced Nutrition diet 4 T est a variety adding and 5 T able B.1.1.1 Macronutrient Summary I Chemical C, Protein table H, O of N foods drops juices) all B.1.1.1 of few in your to form I present amino acids the summarises C, H and monosaccharides, to O being O with disaccharides, saccharides 2 to (lipid) in t he Rich food Meat, sh, I source eggs, C, H and O the 1; ratio they of H form oxygen hydrogen form carbohydrates in information them can test on test a spotting liquid tile foods and (e.g. milk tubes. about macronutrients. and haemoglobin, 3 Some in 4 Transport 5 Protection hormones 1 Energy source 2 Energy storage glycogen oils the (not energy Energy Insulation to 3 Protection in 4 Part 5 Solvent proteins of starch store in for soluble in keratin, water Monosaccharides and disaccharides soluble are are in water insoluble plants) Insoluble against (e.g. insoluble Polysaccharides which source cell proteins collagen) e.g. (e.g. enzymes) water Fibrous (antibodies) bread, pork, properties proteins Enzymes biscuits, Butter, and Physical Globular repair cakes, pasta, I humans 2 1 than and in Growth 2 glycerol atoms atoms or Sugar, acids Fewer tile Y ou table. Functions cereal (sugars) to putting 1 is fatty a by solution. spotting polysaccharides Fat starch iodine results pulses Carbohydrate: for of macronutrients elements and fruit Record Table q a in water knocks membrane vitamins A and D Micronutrients Micronutrients day. Minerals compounds are are t hat required inorganic are made vitamins from simpler (vitamin C) t heir t his, lack so of in ascorbic one mineral by as has or t he t hey to one body plants. substances, diet acid by substances. be Some e.g. make in t he vitamin in small it are animals cattle do You eating make need of each organic t heir ascorbic Humans cannot more quantities complex can not t hemselves. diet. by ver y Vitamins acid cannot compensate do for t he anot her. Minerals Minerals mineral used are to T able B.1.1.2 Roles of minerals Mineral Sources Iron Liver, Water, the make ions, par t in lists some All str uctures as chemical t he iron, soluble as of bones blood copper reactions. more str uctures. are such components such of simple minerals and There impor tant is They in and and long are list green body of or and chloride uids. to salts phosphate Sodium bound ions, and Many enzymes minerals and of t he and Table are ions take B.1.1.2 ones. body vegetables, callaloo/dasheen table inorganic Calcium teet h. ot her zinc, a are water. Function eggs, spinach, Iodine in relatively impor tant metal q are salts. e.g. bush salt Production blood haemoglobin in red cells Production the Deciency of Anaemia blood of metabolic thyroxine which controls rate – less haemoglobin in red cells Reduction in sluggishness metabolic in adults; rate, causes cretinism in the young Calcium Cheese, milk, water, tinned tuna/ Fluoride Water; some Phosphate Water, fresh products, Sodium and potassium Water, Healthy bones clotting; salmon toothpastes vegetables, milk, fresh Strengthens dairy ATP vegetables, milk, liver Nerve acids teeth; Weak bones; in teeth T ooth decay and Rarely bones (DNA impulse blood poor blood clotting contraction enamel production; nucleic liver and muscle and teeth; decient RNA) conduction Rarely decient 64 835292 CSEC HSB Unit B Topic 1.indd 64 08/01/2015 16:02 Nutrition Balanced Vitamins Like minerals, Vitamins vitamin are vitamins substances performs vitamins are and a needed t hat different many of are are tiny needed role t hem in in t he known amounts in order body. by to t he keep There letters in as is us also well diet healt hy. a as each long by 0 Each Mineral salts Also minerals. These are ascorbic acid is vitamin C. The vitamins are divided into ● by whet her Water-soluble ● Examples of t hey vitamins t he are are water t he lipid-soluble B soluble group vitamins or two are A, D and vitamin quantities absorbed e.g. and as in in the diet. They groups not. vitamins needed names, are determined known of small e.g. terms ! day. list Key diet sodium from ions, food as chloride phosphate ions. Vitamins Complex ions, ions, C. compounds K. needed in the diet for specic functions. The solubility likely to variety q be of T able of vitamins found. specic B.1.1.3 Table uses Roles in of determines B.1.1.3 t he vitamins in the A Milk, e.g. B group (e.g. B water food in are which used t hey for a are great Function butter, liver, fresh rods extract, liver, eggs Deciency Manufacture vegetables, carrots Yeast soluble) of vitamins body Source soluble) type t hat body. Vitamin (fat t he shows and in Many the of eye uses, rhodopsin (see page particularly in the Nightblindness 233) in Many, e.g. nervous and muscle 1 vegetables C (water Fresh soluble) e.g. fruit, respiration particularly citrus fruits, Healing oranges of of systems wounds, collagen the body, in e.g. stimulates many in formation Scurvy places out; skin uptake of and iron in are – can less efcient bleeding lead to gums, teeth fall anaemia gums; from the gut D (fat Liver, soluble) butter, sunlight on cheese; also action of Stimulates and skin absorption phosphate therefore from important of calcium Rickets – weakened bones food, in bone formation K (fat Green soluble) vegetables; produce E fat Green soluble this in gut the bacteria Clotting of blood Prevent chemical vegetables membranes Practical The test for vitamin Poor clotting of blood colon damage to cell Red blood cells break easily nerve cells are leading break fragile to and anaemia; down Activity C Requirements ● test tubes ● test tube ● 1 cm ● beakers ● 1% several ● racks foods, oranges and e.g. lemons, grapefruit 3 by syringes vitamin C dissolving or dropping solution 1 gram pipettes ● 1% DCPIP solution ● eye protection prepared of a vitamin 3 C tablet in 100 cm of water 3 1 Put 1 cm 2 Using the DCPIP syringe DCPIP The 3 a of blue one or Record the of a drop DCPIP number solution dropping at a solution volume into of Shake turn vitamin test pipette time. will a C tube. add the 1% tube vitamin after C solution adding each to drop. colourless. solution required to do this or the drops. 65 835292 CSEC HSB Unit B Topic 1.indd 65 08/01/2015 16:02 Balanced Nutrition diet 4 Extract a 5 the juice Repeat you steps know 6 Repeat 7 Compare in a you is the had 1–3 rich test the table. vitamin If to C Calculating student variety The of a add of a of C fruits. test content a DCPIP C the you to to out content the 0 term a good lemon, an orange and a idea to use a fruit that and another juices can by record decolourise it. type of juice. presenting your the of volume Rate the results juice juices in that order of of fruits activity as described above and tested a of that 3 drops drops. for it took 6 drops of 0.1% vitamin C solution to DCPIP . to in decolourise lemons Therefore calculating drops of 0.1% number of student recorded drops of the the as in the the DCPIP , 0.1% percentage of concentration vitamin there must solution, vitamin of C as is vitamin C it be double took half the 0.2%. in the foods is: C 0.1% extract the Number results of drops Orange 2 Grapes 8 in of a table: extract 36 a Calculate b Explain the why Dietary bre Dietar y bre major is lowest). practical Potato Key It tube of syringe (highest content Food A e.g. first. clean C the the C × The fruits, skills found the formula number to content took vitamin The one vitamin used vitamin student number for in vitamin carried lemon the different foods. decolourise If several using you Maths A from grapefruit. is vitamin these found component C content results are mainly of these unlikely in dietar y of plant bre is to three be foods. accurate. mater ial, cellulose e.g. vegetables. from t he walls of plant ! cells. Fibre helps Indigestible to bowel prevent matter that constipation cancer. and give t he Fibre t he provides muscles small and large constipation . By (diver ticulitis) and passes body all t he when bulk to t he somet hing intestines. regularly way bowel are food so to work on and t he passed stimulate Stimulating removing cancer t hrough faeces to are push digestive t he per istalsis faeces, less per istalsis all food and along helps to prevent inammation of t he likely to system occur. so is Dietar y egested colon bre from t he out. Water Water water is an and present in impor tant we lose body a constituent great uids deal and in of each cells. t he day, It is diet as so especially found much in hot of t he body climates. is Water is in: 66 835292 CSEC HSB Unit B Topic 1.indd 66 08/01/2015 16:02 Nutrition ● ● ● ● Teeth blood plasma, lymph, tissue which anot her uid, cytoplasm body which – makes many uid up t hat surrounds cells about 55% transpor ts all contain t he cells of our blood materials inside approximately our volume around t he body bodies 60–70% 0 water. Did you know? ? Water is vital for body functioning. We need it as a: There ● coolant in t he solvent for skin large are many bacterium ● t he transpor t of water soluble substances, including carbon dioxide and waste substances (see page ● solvent for water reactant in foods t he soluble chemical substances reactions, e.g. inside tissue hydrolysis uid and reactions cytoplasm digestive act when we and on the produce vitamins of vitamins are coli. These cellulose the B vitamin group. absorbed K in and These through digest the in Escherichia our the 92) food ● in particularly absorbed bacteria nutrients, microbes intestines, colon and used by the body. system. These are useful bacteria. Questions 1 State the 2 What elements 3 a What make 4 a is a a a source 5 types are elements up Name that three Naming proteins are in fats made from? (lipids)? b What are the components that food that is source a good of source of starch. c in case, protein. Name a b Name different food a different that is a food good lipids. a following carbohydrate. triglyceride? good of of different vitamins food and each minerals: state vitamin A, a good vitamin source , B of the vitamin C, vitamin 1 D, 6 iron Which B.1.2 and calcium. vitamins are a fat soluble and b water soluble? Teeth Learning By T eeth We the should have two childhood sets and of teet h in permanent our lifetime: teet h t hat milk replace (deciduous) t he milk teet h teet h in from t he ● age end be of The six years human describe onwards. adult ● dentition is composed of four types of teet h topic you to: the structure and of of relate the tooth to state the a typical structure its tooth of a functions (see ● Figure this able function about outcomes causes of tooth B.1.2.1): decay ● incisors – chisel-like for biting ● ● canines – pointed, wit h no par ticular function in humans alt hough ● help t he incisors bite into food describe tooth t hey outline for ● ● premolars molars You can see dentition your – – cheek cheek t he by mout h, teet h, teet h, ridged ridged difference for between writing out dental t he jaw over top for process of the your ways to care teeth. grinding grinding. t he milk formulae. t he the decay lower dentition Each and formula t he refers permanent to half of jaw. 67 835292 CSEC HSB Unit B Topic 1.indd 67 08/01/2015 16:02 Nutrition Teeth Figure Did you B.1.2.2 shows t he str ucture and functions of enamel: white As a young child, your canine toot h. very shiny hard material, dental 96% formula a know? was: mineral mainly salts calcium phosphate 2 1 i 2 c 0 p 2 1 m 2 dentine: 0 tooth the main substance, crown: As an adult, your dental formula exposed mouth will yellowish or like bone but be: has fine 1 2 c 1 cytoplasm 3 p 2 harder; canals containing 2 i ivory, to cavity passing m 2 through it 3 neck: gum surrounded by pulp soft cavity: contains gum incisors small blood nerve fibres, sensory vessels, pain and receptors and canine tooth-forming cells root premolars embedded in cement: molars bone-like, socket fixes tooth bone membrane: allows in fibrous in marrow cavity: i tissue nerve blood socket slight movement tooth in of socket connective covering jaw bone jaw bone vessel molars canine premolars p In Figure B.1.2.2 humans t he Structure upper of and a canine lower tooth jaws have t he same number and type of incisors teet h, p Figure B.1.2.1 Human adult as seen in Figure B.1.2.1. dentition Care Too of muc h bacter ia enamel (see teeth sugar in of our Figure neutral – our in t he teet h. B.1.2.4). neit her As pH acid of can result in t he acid accumulates is a sugar toot h tur n not sugar pH diet mout hs measure into of decay. acids in t he acidity This whic h teet h and is because att ac k t he pH alkalinity. t he decreases pH 7 is alkaline. eaten pH falls as bacteria pH returns to 8 break mouth to sugar down normal acids about after 30–45 minutes normal of pH 7 mouth 6 pH beneath which can decay .. I I occur 5 , p Figure B.1.2.3 showing signs An of extracted 4 I 3 I I I during time can this I I +I decay occur I I I I Time molar decay p Figure B.1.2.4 How the pH in your mouth will vary after eating sugary food 68 835292 CSEC HSB Unit B Topic 1.indd 68 08/01/2015 16:02 Nutrition Plaque Teeth is a t he teet h. t he food, mixture Bacteria of in saliva, t he food plaque and bacteria produce acids which and forms toxins naturally (poisons) on from 0 Key terms ! par ticularly if t he food is sugar y. Plaque Dental caries are caused by t he acid dissolving t he enamel and t he and of t he toot h. This leads to a cavity in t he toot h, which may leading to food t he mout h. toot h t he and toot h disease These gum may is caused cause meet. fall by toxic inammation Eventually out substances later in t he of gum released t he gum may pull at t he back by bacteria the point from where Practical t he toot h and area that is Indicator paper or various ● household spotting Indicator tile or cell rubber eye 1 Place tube. cork 2 3 a colour test or If small test cleaning antacid chart tubes cork and colas, with stoppers plastic quantity tubes The swelling Blood white to of blood remove an ow cells bacteria NEUTRAL fluids, tablets fruit are of mouthwash, bottled gloves in detergents, each used, item cover on a each spotting one shampoo, water with or milk or in tile a rubber ALKALI weak strong juices, dissolved vinegar, weak 2 3 4 5 pH bleach, tap test bung 7 8 9 10 11 12 13 14 value as in shown by Universal different Indicator water, p a 6 water, Figure B.1.2.5 Colour chart Figure B.1.2.6 Universal Indicator T eeth not or stopper. Either or bungs protection by debris. colour ● decay substances, 1 ● T ooth and ACID e.g. Universal saliva surface scale solution ● the released infected. together strong Universal acid increased and Activity pH caries by Inammation life. Requirements ● to bacteria. t he collect the bacteria, teeth. caused in is Investigating of sticks toot hache. Dental Periodontal layer that become of infected, A dentine place place a Compare a few piece the drops of of Universal Universal colours with Indicator Indicator the colour paper chart solution into and each give a into each item item. pH value to each substance. Place the record of substances the Prevention Toot h q T able 1 of decay on tooth can be prevented Brushing T eeth T oothpaste and should at by Use toothpaste a of 1 taking and bacteria T oothbrush Your 4 Dental Dental to 14 good and take photographs as a care of t he teet h. oss Disclosing Disclosing so you Eating habits good Eating to are sugary other damages juices the can on to the very foods to as not thoroughly after each meal oss These concentrate thoroughness at taking care for Do on. their not is a least your acid teeth. the enamel food protects and particles against the good once and plaque. prevent day. on your ossing. teeth They brushing. of your Also teeth. avoid preservation. eat to way a plaque brushing feed the months. and of bacteria contain the in also stain your of dislodge. 2–3 teeth dental chewed. that every strengthens some always between use this remove changed which of motion antiseptic important which enamel all be where check habits avoid and see be debris should tablets can uoride does contain should We circular brushing brushing removes decay. a plaque. contains after mouthwashes tablets a that in remove that toothbrush tooth are brushed to mouthwash 3 oss be bedtime use Some 6 scale B.1.2.1 mouthwash 5 pH decay and 2 the results. too often Always the soft The try drinks acid between meals. p are bottle openers! 69 835292 CSEC HSB Unit B Topic 1.indd 69 08/01/2015 16:02 Nutrition Enzymes 0 q Talk T able ? 7 T ooth B.1.2.1 Continued about Dentist Dentists check regularly to leading condition, Discuss this statement with friends, family and seems that if glass you of overnight it is a collection to unlikely a tooth leave controlled Instead, use the experiments say they that that or it important to visit the dentist before they get to visits llings can be or tooth every extraction. year, but if not If too your then teeth every are 6 in good by most months is dentists. practice Use your teeth for what they do best – eating. teeth in the adult Questions have try out 1 What is 2 Name 3 Give the maximum number of human dentition? a to out the four types of teeth. your a pulp role for each of the following: a enamel, b dentine, c cement, and cavity. and discuss rots d others videoed. and ‘cola Good 4 What is dental caries? 5 What is periodontal 6 How Assess the teeth’ should you disease? take care of your teeth to avoid dental decay, others. injections, Learning By is resolved experiment. carried photographed evidence will to Internet nd with It are disappeared. you teeth properly claim decay. the and have that of have know put cola will It the any problems teachers. 8 Everyone a for any your advised in teeth that decay serious story your ensure the end B.1.3 outcomes of this topic fillings and extractions? Enzymes you Enzymes should be able to: Catalysts ● define the term are biological ● explain how an enzyme describe the catalysts t hat t hat are speed made up by chemical cells to reactions. speed up Enz ymes chemical are reactions in works t he ● substances enzyme properties body. Enzymes catalyse reactions t hat would ot her wise take too long of to enable us to sur vive, e.g. wit hout enzymes to help us digest our food we enzymes. would The t he not vast by are ver y are secreted Each is Figure B.1.3.1 This meal is If we and within had no to would this digest. be hours enzymes intestines, years 48 in meal Life as impossible of being our named into are in t he found active is a site, t heir proteins (see alimentar y cells food proteins af ter digestion inside enzymes are our by where and do are ver y proteases B.1.4). it must t hey much! unchanged substrates, Unit canal, to e.g. and lipids Alt hough be at by end lipases. t hese remembered control t he carbohydrates of are They enzymes t hat most metabolism. work complex which t hree-dimensional has a par ticular shape molecule. Par t where reaction t he of its str ucture occurs. used to explain how t he active site works is shown in Figure B.1.3.2 shows t he and is substrate called t he molecules lock and tting key into mechanism. t he active site The and diagram being take know without mechanism eaten. stomach would we enzymes are from fully The digested energy carbohydrases, enzyme t he of They impor tant enzymes How enough majority reaction. digested p have it enzymes conver ted enzymes down to into to a product catalyse product molecule. reactions in The which practical substrate activities molecules involve are using broken molecules. 70 835292 CSEC HSB Unit B Topic 1.indd 70 08/01/2015 16:02 Nutrition Enzymes 1 2 } enzyme On a the enzyme particular known active p as active is with the 4 41 .. site Substrate shape 3 molecules The complementary fit shapes substrate into such site the a molecules active way that site a A product in of the reaction is now two made up Product substrates end B.1.3.2 Lock and key mechanism of enzyme Tr y this yourself If a the Exam word the activity of catalase in different Requirements –ase, do not made hydrogen peroxide (from a knife, ● of small have or glasses peroxide extremely enzyme cutting toxic is made to cells catalase is by so peroxide to peroxide produced People gloves 1 use Add as volumes of small Record rate it the the quantity also try results different Properties a of as of is many board and few of reduce t he t he speed We do of and The hair. Make the such in the we t he need need to t he energy inside in numbers of reactions Enzymes are of buy you is and at wear to t he will rate end specic. of one substrate occur. The peroxide or quantity design of needed to large t he before down maltose; and t he to enzyme water active type of enzyme is to This body of a into stomach that which to start is the protein. it is formed. the more made. animal tissues. pharmacies. some suitable meat of plastic that containers. you have at home. yeast. properly the for vigour controlled of molecules would sur vive reaction t hey occur wit hout quantities of t hey become site of must will t hat catalase and means t hat reaction. molecules Amylase peroxide t he pepsin, breakdown the experiment to reaction. to at react anyt hing enzymes enzymes speed worn toget her. up – to catalyse B.1.3.3 to vigorous is t only Note into are huge out. t he amylase t he enzyme Catalase is in not type of Figure t he catalyse catalyses oxygen. each active t he t hat specic B.1.3.4 site reaction reaction will enzyme in breaks not for will how before where which down accept t he speed shape reaction t his occurs. starch is broken hydrogen starch hydrogen only t he as a When hydrogen reaction raw liver peroxide with lots of is there is a frothing t hem. t hey catalyse Figure added approaching because and Ver y 0 Key terms ! Catalyst t he ending plenty corrosive. order t he order make at of as are enzymes reactions not names there processes. as tissue, catalase plant can many soon tissues active some sure as animal more you from down more in which vegetables then and catalase small in plant the very any tissues unchanged up be Many small p Enzymes it gloves product broken therefore hydrogen very waste be oxygen. and their it a to peroxide, bleaching use in and activity hydrogen for could water relative you equal a Y ou 3 it when Pour 2 the some cells needs present hydrogen need plastic ● hydrogen Investigate -ase enzyme. spoons cups Hydrogen in an but digestion pharmacy) Y ou will the reaction tissues in The the tip ends name enzymes Investigating is of remains at action ✔ It enzyme unchanged produced 0 ● The occurs Figure ● is released substrate Speeds up remaining unchanged Enzyme A speeds up Substrate changed biological the rate The during Product The formed a in of a reaction at the catalyst that reaction. substance a end. that is reaction. substance that is reaction. peroxide. 71 835292 CSEC HSB Unit B Topic 1.indd 71 08/01/2015 16:02 Nutrition Enzymes Factors that affect enzymes A Enzymes B In are extremes do not that affected of pH function we by and as two on – temperature, catalysts. experience factors enzymes Within Ear th, temperature the enzymes lose range of respond and pH. their special moderate to changes str ucture and temperatures in temperature C by increasing or decreasing the rate at which they work. D T emperature Figure p Figure B.1.3.4 Enzyme B.1.3.5 human See question 3 on page t he effect of temperature on t he action of a enzyme. 76 Look carefully from to maximum. a an lef t at axis t he noitcaer maximum shows specificity. optimum optimum to t he graph right. The by From working 0°C to temperature temperature temperature for of at t he steadily 37°C t he which t he enzyme. 37°C. This across rate of t he maximum All human be explained can horizontal reaction increases rate occurs enzymes by t he is have kinetic rate t heor y. t he The enzyme temperature fo toget her t hey so etar t he permanently molecules t here collide temperature, temperature substrate increases, because optimum and into rate is a greater each rapidly changes move t he ot her chance more decreases. shape around of of faster as t hem tting frequently. Above This t he is because enzyme t he t he higher molecules so optimum temperature 0 10 20 t he 30 40 50 70 60 temperature / °C Heating is a get p Figure effect the by B.1.3.5 of rate a This increasing of a human graph shows temperature reaction that is active sites proteins it back again. on catalysed of the hot egg oil is you practical effect look of and amount start activity to temperatures You see shapes. of Protein this 60°C or higher molecules happening lose when denatures their you shape cook an proteins. and egg. This cannot of the egg cooling the protein white will Practical goes albumen. solid. restore it to This the Heat is an egg in boiling The white denaturation liquid sate of a of fresh water albumen or and no egg. Activity tip reading page on 63 the effect of temperature converts starch to sugar. on amylase the ‘investigating temperature back specic change. mostly Investigating Before t heir the enzyme Study to non-reversible 0 ===========::] ✔ loses Amylase the amylase’, where colours when samples of the The reaction change mixture is followed are tested by with recording iodine the solution. the Requirements iodine A test for blue-back present. In starch colour this is described. means activity, substrate so will be beginning of the reaction, when it has all been starch starch present is at but is the ● test tubes ● spotting ● test tube ● timers ● permanent ● thermometers ● dropping ● 1% starch ) ● 1% amylase beaker ● iodine racks tiles the markers for test tubes not converted pipettes to or plastic 3 syringes (1 cm solution 3 and 5 cm solution products. ● water of baths water (use plus ice a for cold in solution potassium (iodine iodide solution) temperatures) 3 1 Put 1 cm of amylase of starch into a test tube and label. 3 2 Put 3 cm 3 Place each Record 4 After the the 15 test into tube into temperature minutes reaction mix mixture another a of the warm the two using test a tube water water bath, bath solutions, dropping and label. e.g. and start a at 35°C keep it timer and for 15 minutes. constant. take a sample of pipette. 72 835292 CSEC HSB Unit B Topic 1.indd 72 08/01/2015 16:02 Nutrition 5 Enzymes Place (this 6 7 this should turn Clean the iodine solution. Continue colour 8 sample the spotting taking take another samples every record the whole procedure the temperatures, tile and add e.g. time 10°C, in sample 30 after seconds 30 T est tubes drop of iodine solution containing a seconds until there and is no test with blue-black seconds. using 20°C, water 40°C baths and at four different 70°C. 3 9 a blue-black). pipette, and Repeat into 3 1 cm water and 3 3 cm starch, and b 1 cm 3 amylase and 3 cm water should also be set up and sampled at each temperature. 10 Record the results as T emperature / °C a table. Time for the blue- Rate = 1000 / to time/seconds –1 colour black disappear / seconds Time a taken long time starch the is in all for the broken times taken for into the starch starch down relative seconds for to very disappear broken quickly, rates each to be of then enzyme tube as is not down the the then rate activity by rate the is of rate very reaction. is very fast. dividing Y ou 1000 If it slow. can by the takes If the convert 0 ✔ time Exam When follows: you enzymes correct relative rate of enzyme activity = If no rate a t = time change of enzyme Plot Put is a taken terms, in activity 0. graph of Explain c Why is water your it = the relative on the such to as use on the rate denaturation colour rate of horizontal of the iodine, enzyme axis of assume activity your that against graph the of optimum, and reaction, lock and key. relative temperature. paper. results. necessary and the questions sure 1000 / t seconds). recorded temperature b in answer make maximum, (where tip amylase to at include each test tubes with water and starch and with temperature? pH Enzymes are also affected by different pH, t he enzyme will is and in denatured. enzymes some solutions Figure from t he B.1.3.6 digestive If work t here shows an enzyme rapidly will t he system, be in no effect pepsin is put some into reaction of pH and solutions values on at of all two pH, as of pepsin slowly t he enzyme different amylase in human amylase. noitcaer ot hers pH. fo can value. the be seen, Either rate Which of each side of reaction. means that enzyme the This the is active optimum, is because active site over a changes the has a pH range in pH affects shape that of pH cause the around a steep shape does not of an optimum decrease etaR As in the enzyme. accept substrate 2.0 molecules. optimum amylase The pH. is two enzymes, Pepsin found in is the found pepsin in mouth the and amylase, stomach which has a do where pH not there around work is an neutral. at the acid 7.0 pH same pH and p Figure B.1.3.6 on enzymes, two shows the pepsin effect and of pH amylase 73 835292 CSEC HSB Unit B Topic 1.indd 73 08/01/2015 16:02 Nutrition Enzymes Practical Investigating Amylase using to acts iodine keep the on effect starch, solution mixtures Activity of as of pH on turning in the enzyme it into rst and amylase sugar. practical substrate This change activity. at is Buffer chosen detected solutions values of by are used pH. Requirements ● test tubes ● test tube ● permanent ● dropping racks markers pipettes for or test plastic 3 syringes ● water ● timers 5 cm Put starch 1% amylase ● iodine in buffer ● solution solution potassium (iodine iodide solution) solutions of a range of pH 3 of 1 cm and 1% ● solution bath tube ● ) 3 1 thermometers 3 and (1 cm tubes ● amylase and 1 cm of a buffer solution at pH 7.0 into a test label. 3 2 3 4 Put 3 cm Place these reach this After of starch in a water minutes iodine the suspension bath at into another 30°C for 15 test tube minutes and so label. that the solutions temperature. reaction of Clean for 6 15 the drop 5 of mix the mixture using solution pipette, two (this take solutions, a clean should another start a timer dropping turn sample and pipette. take Place a sample this into a blue-black). after 30 seconds and test starch. Repeat until there is no blue-black colour and record the time in minutes. 7 Repeat and the experiment using buffer solutions at pH 4.0, 5.0, 3 8 6.0, 8.0 9.0. Controls should be set up at each pH using 1 cm 3 water, 1 cm buffer 3 solution 9 Record and the 3 cm results starch as pH a solution in each tube. table: Time for black the colour blue- Rate to 1000 / time/ = –1 disappear / seconds 10 Convert the practical 11 Plot the 12 a times relative rates of enzyme activity as in the previous activity. graph of horizontal Explain into seconds your relative axis of rate your of enzyme graph activity against pH. Put pH on paper. results. 74 835292 CSEC HSB Unit B Topic 1.indd 74 08/01/2015 16:02 Nutrition Enzymes Practical Investigating Pepsin acts cloudiness on of solutions are values pH. of the Activity effect proteins, the of pH e.g. to keep the protease albumen, suspension used on clears mixtures as as of the enzyme, reaction albumen enzyme is proceeds broken and pepsin the down. substrate at Buffer chosen Requirements ● test tubes ● test tube ● permanent ● dropping racks markers pipettes for or test plastic 3 syringes ● water ● timers 1 Put tubes ● thermometers ● 1% pepsin ● 1% albumen ● water bath ● buffer solutions solution suspension 3 and (1 cm 5 cm ) of baths 3 of a range pH 3 1 cm of pepsin and of albumen 1 cm of pH buffer 7.0 into a test another test tube tube and label. 3 2 Put 3 Place these reach this 4 3 cm After this cloudy 5 6 in a suspension water bath at into 30°C for 15 minutes so and that label. the solutions temperature. time, mix the suspension to Repeat the experiment Record the results as two clear. solutions Record using a table pH and this buffers and time time 4.0, calculate how in long it takes for the seconds. 5.0, the 6.0, 8.0 relative and rates 9.0. of enzyme activity. pH Time for Rate=1000 / time the –1 suspension (seconds to I 7 Plot a graph of relative rates of ) i clear / seconds enzyme activity against pH. 3 8 Controls should be set up at each pH of 3 1 cm water, 1 cm buffer solution 3 and 9 Explain The substrate a your high Enzymes available. of substrate work The concentration remember suspension. results. concentrations reactions. will albumen 3 cm from much rates of of and A.2 if are Kinetic t hat also t here reaction enzyme. Unit enzyme faster is a also t heor y molecules inuence high much also move t he rate of concentration faster if explains around t here t his. quite of is You freely 0 ✔ Exam Exam solution. If t here is a high concentration of substrate molecules t he chance t hat t hey will collide wit h enzyme molecules is higher concentration is of substrate molecules is low. Similarly, if different can using parts often be information is a good of point your to go course. back t han to t he by t hen This if questions answered from in tip Unit A.2 and read about kinetic t here energy. is a high concentration collisions between concentration There are Many poisons, is some of enzymes enzyme and t here substrate are going to molecules be many t han if more t he enzyme low. chemicals, such as called cyanide, inhibitors are enzyme t hat stop enzymes working. inhibitors. 75 835292 CSEC HSB Unit B Topic 1.indd 75 08/01/2015 16:02 Digestive Nutrition system Questions 1 Draw annotated reaction in diagrams which a to show how molecule substrate an is enzyme broken catalyses down into a chemical two product molecules. 2 Name c 3 Imagine + By the end of this topic AB Explain why why we 5 Describe 6 What is family be able how identify the digestive parts system: b proteins and D à reactions Explain do your not enzymes scale? some will in pH Digestive make to would affect many and changes you use chemicals studied never catalysed stomach respond household in to the How be by the enzyme shown in answer. need enzymes who CD an in in cells, Indicator demonstrate at our and temperature. Universal to science enzymes intestines. the solution pH scale to school? enzyme? system of the alimentary canal and digestion is t he breakdown of food into molecules t hat can be absorbed t he body. There are two forms of digestion. Mechanical d igestion is t he breakdown of large pieces of food into stomach, ileum, large these two changes smaller pieces. Mechanical digestion involves chewing and t he liver, churning relate lipids, mouth, much pancreas, a of ● oesophagus, ● down to: following duodenum, break you into the + C we pH and friend do Digestion ● a have the paper How these Structure should and B.1.3.4? B.1.4 outcomes à Figure a that reactions: of or Learning B two Which b 7 enzymes carbohydrates. A 4 the action of t he stomach. intestine parts to their ● Chemical d igestion to soluble is t he breakdown of large, insoluble molecules functions ● describe digestion in smaller, distinguish and ● between t hey can be absorbed. Enzymes t he chemical digestion of large food molecules. the ● role of canal is adapted to enable us to carr y out: ingestion by taking food into our bodies and ● importance alimentar y egestion excretion explain t hat canal Our ● so the catalyse alimentary molecules enzymes mechanical digestion by breaking up large par ticles of food into smaller in pieces wit h a larger surface area digestion. ● 0 in ! ● Key large, absor ption small, down food digestion large, small, by using enzymes molecules to by providing a soluble molecules from into smaller nutrients Breaking large form to catalyse smaller, surface area t he breaking soluble for t he of bonds molecules digestion insoluble soluble to all par ts of t he t he body gut into where t he movement blood, assimilation which of distributes occurs pieces. ● Chemical digestion insoluble terms Mechanical of chemical egestion by removing the undigested remains of the food we have eaten. Breakdown molecules to molecules. 76 835292 CSEC HSB Unit B Topic 1.indd 76 08/01/2015 16:02 Nutrition Figure Digestive B.1.4.1 alimentar y is a highlights canal drawing of as t he a t hese simple ideas tube alimentar y wit h a passing canal and ver y simple t hrough t he associated diagram body. of t he Figure B.1.4.2 0 system ! Key terms organs. Ingestion body T aking through the food into the mouth. ingestion Egestion The undigested secretion physical large are digestion: particles broken small of juices food down of removal food from of the anus. digestive containing enzymes into particles chemical large broken small digestion: molecules down 0 are into ✔ assimilation soluble in molecules a cell, using e.g. small molecules Do Exam not confuse egestion with to excretion. make tip Egestion is removal larger of undigested material from through the the ones absorption digested of large intestine food Excretion of the of undigested Figure ideas B.1.4.1 of Diagrammatic removal inside whole of reactions body. cells products that have throughout There is more food about p is chemical occurred egestion anus. version of the alimentary canal showing the excretion in Unit B.5.1. key digestion Mouth Mechanical ● ● Incisor The ● The of bite t he food into is by chemical food to pieces, moving secreted by digestion break especially smaller helps which and teet h, into tongue saliva, ● teet h rest chew digestion t he a small premolar process food t he off six star t in t he t he 0 mout h. teet h mout h as and term t he molar teet h, Mastication Chewing food. mastication. and glands Key ! pieces. known salivar y in in mixing t he food wit h head. The smell, taste and the texture of food in the mouth all stimulate the secretion of saliva, which is the rst digestive juice to be secreted onto food. Saliva contains the enzyme salivar y amylase, which catalyses the chemical digestion of starch to maltose. ● Saliva also contains mucus to help lubricate food as it is swallowed. It has a pH that is near 7 .0, which is the optimum pH for amylase. Swallowing Swallowing tongue to mout h. ot her is a roll Apar t actions complex food into from t he of series a ball of actions (bolus) conscious swallowing are act and of t hat occur push it pushing controlled to when t he t he you back tongue use of your your backwards, t he automatically. 77 835292 CSEC HSB Unit B Topic 1.indd 77 08/01/2015 16:02 Digestive Nutrition system Use Figure B.1.4.3. B.1.4.2 You can to identify also see the the organs hear t and of the the digestive lungs in the system in soft mouth Figure thorax. palate cavity (buccal cavity) throat (pharynx) mouth epiglottis tongue salivary gland gullet (oesophagus) diaphragm ring of muscle (pyloric stomach llams liver gall sphincter) bladder duct pancreas ileum egral bile enitsetni duodenum enitsetni colon caecum appendix abdominal cavity rectum anus p Figure B.1.4.3 The virtual body; this ring of muscle computer around generated main image organs of shows the the thorax position (chest) of and anus the abdomen p Figure B.1.4.2 Human alimentary canal and its associated organs Oesophagus bolus bolus is moved along the gut Af ter ● ● swallowing, gravity, if you a food are bolus standing travels or down sitting t he oesophagus by: upright peristalsis – a wave-like contraction and relaxation of the circular muscles in circular circular the oesophagus that pushes the bolus along as you can see in Figure B.1.4.4. muscles muscles contract relax Stomach p Figure the of B.1.4.4 Food oesophagus circular bolus of by muscles food. This is the just pushed along contraction behind movement each The stomach end where it is a highly joins t he muscular small sac wit h intestine. a Look t hick at ring Figure of muscle B.1.4.2 for at t he t he pyloric is sphincter muscle at t he junction between stomach and duodenum. The peristalsis stomach stores t he is food Cells in food made t he wall for into of a t he approximately semi-solid stomach protease, pepsin. Hydrochlor ic infection via food When t he decreases Refer to our food to is amino acids a and mixed about Figure Pepsin is 1.5. B.1.3.6 protease called it Any on enzyme acid t hat or to as of t he its to in conr m t his. down polypeptides. acid protect by amylase t he t he we and us action t he against have ingested. stomach food protein Its churning chyme. bacter ia secreted breaks By hydrochlor ic secreted most salivar y 73 is hours. known secrete t he page peptides mass acid kills wit h 3–4 stops into optimum its working. smaller pH pH is chains of 2.0. 78 835292 CSEC HSB Unit B Topic 1.indd 78 08/01/2015 16:02 Nutrition The Digestive X-ray which in does diseases of Figure not t he B.1.4.5 allow t he stomach is taken X-rays and af ter to t he person penetrate. This took is a one barium way to o ___ meal, diagnose ✔ intestine. Study Pyloric Duodenum The is Periodically t he pyloric sphincter muscle relaxes and chyme is released known duodenum. it is ver y acid The stomach and t his does would not release damage t he all wall of of its contents t he at more delicate t han t he wall of t he stomach. food t hat juice from is mixed t he wit h bile, which is secreted by t he entering liver, and for is in t he pancreatic meaning terms liver and stored in t he gall bladder. The entr y of t he stimulus Figure t he B.1.4.7 , pancreatic neutralise The for pH most is t he duct. about down contains substances droplets Figure t he of drops. lipid The gallstones cannot and called large t he means so bladder. mix are wit h bot h alkaline pH (duodenum proteins, stop of bile lipid surface t hat salts As alkaline in t he and can you can pancreatic be and see juice uids small ileum) carbohydrates t hey drops t he enzyme digestive of bile are the It to are ● amylase, is to t he t he organ Cells rise cells which proteases, Figure of as comes grip from tightly. and a a word Biological easier remember to if they are you derived. in t hat intestine. is where lipids are a can much is not is just It system from is t he much see t he larger have t hat liver effect access t he at smaller surface chemical put to lipid of much digestion in t he t his area droplets risk into These more as t he have people in t han got who duodenum have and properly. B.1.4.7 . pancreatic lipases, ring known in lying just wit hin beneat h t he t he pancreas stomach. make an Find alkaline it on uid Figures t hat in pH of t he food in t he duodenum to about p Figure conver ts any tr ypsin, which which conver t t he shows food A peristaltic down to the wave lowest the part stomach secrete: e.g. B.1.4.7 B.1.4.5 8.0. of ● Any is sometimes how moving ● body juice contributes These which Greek absorbed. emulsiers. many You molecules chemically. ow into have Emulsication t he t hat tension. droplets t hat unchanged fats t he gall to juice intestine all t he duct provide molecules smaller healt h pancreas B.1.4.2 t he substrate. digest – from bile pancreatic and small place bile t he pylorus, Ancient fat The t hat Pancreatic The of This remains smaller. The reducing lipid and acid smaller change by Bile takes of down substances B.1.4.6. t heir 8.0. into Emulsication Bile release ows stomach digestion broken t he bile name. stomach food know is strange t he pancreas. produced an gatekeeper. in understand Bile the a the is sphincter. duodenum is of once duodenum The as from muscle much end into word as tip sphincter lower comes t he system t he remaining conver t emulsied duodenum and starch to maltose polypeptides to lipids acids its to fatty relationship peptides to and t he glycerol. liver and lipid drop lipid droplets pancreas. p Figure B.1.4.6 Emulsification of fats Ileum Digestion is membranes These ● ● completed here of lining t he enzymes Maltase cells are breaks listed down by enzymes t he ileum t hat or in work t he eit her on cytoplasm t he of cell t hese surface cells. below. maltose to glucose. Sucrase (also called invertase) breaks down sucrose to glucose and fructose. 79 835292 CSEC HSB Unit B Topic 1.indd 79 08/01/2015 16:03 Absorption and the fate of digested Nutrition products ● Lactase breaks down lactose to glucose and galactose. liver ● Peptidases break down peptides into individual amino acids. gall All bladder t hese enzymes work in a neutral or slightly alkaline pH. The roles of t he stomach enzymes bile in chemical digestion are summarised in Table B.1.4.1. pyloric duct sphincter q T able B.1.4.1 Summary table of the enzymes in the digestive system duodenum pancreas Enzyme pancreatic Food amylase Salivary duct Pepsin p Figure B.1.4.7 The the digestive with help you enzymes make a in of pH, organs that learn are of Polypeptides Polypeptides Peptides Starch Maltose the associated about Pancreatic amylase Lipase Lipids Sucrase Sucrose Maltase Maltose Lactase Lactose Peptidases Peptides Fatty acids Glucose and glycerol and fructose and galactose Glucose their of (milk sugar) Glucose Amino acids various Questions system, the effects enzymes on 1 food Explain why processes substances. Key (triglycerides) system the digestive names and the digestive showing the the secreted 0 Protein tip the table regions their Product(s) Maltose it Study ✔ T o other system (substrate) duodenum Trypsin showing substance Starch in 2 What 3 a State what b What is term is mastication the the digestive advantage happens the and of digestion are necessary system. secreting to advantage chemical the of hydrochloric surface this area of the acid into lipids in the stomach? Figure B.1.4.6? change? ! 4 Absorption Movement of Describe journey food into molecules the blood Learning By the end should be from and the of this to happens through the a molecule digestive system of protein from the in a piece mouth to of the meat small on its intestine. intestine lymph. 5 topic Where B.1.5 outcomes able what soluble you is bile a secreted, Absorption digested b stored, and and the c active fate in digestion? of products to: Absorption ● describe in ● relation describe the ● ● the villus to structure Absorption absorption what products happens after to absorption describe the role describe the causes of the liver is t he movement digestion into t he blood especially t he Figures B.1.5.1 of and is ver y of t he well t he small molecules lymphatic adapted for system. t his produced The small pur pose as by chemical intestine, you can see in B.1.5.2. and Str uctures effects ileum and constipation in t he body t hat are well adapted for absor ption have large and surface areas for as much movement of molecules as possible, a t hin lining diarrhoea ● describe of a how villus is the to give a to take away to its absorption related of The function of nutrients ● describe ● what happens products after of distance for features long molecules to t he molecules t hat t he lengt h – make nearly 6 maintain ileum metres a to steep travel and a good well in concentration blood supply adapted for gradient. absor ption are: lengt h to ● the shor t structure folded internal surface digestion absorption. ● many villi 80 835292 CSEC HSB Unit B Topic 1.indd 80 08/01/2015 16:03 Nutrition Absorption villus: area large for blood surface capillaries: therefore absorption much very and the fate of digested products Q _ __ extensive, absorption ✔ Study This at is a Unit tip good A.2.2 opportunity to remind to look yourself microvilli: about provide large a diffusion of molecules. very surface area p Figure B.1.5.1 micrograph intestine of This villi shows they are to area for food (×30) give in how a electron the very absorption small closely of large packed surface digested mitochondrion epithelium: therefore one molecules easily move blood system p ● across Figure detail their t he ● villi cells contain each t he The is is rich water villi a to in to a long, of is the folded wall of internally the ileum and has showing many two villi. villi The with have microvilli, which are projections of t he many of mitochondria molecules, such to as supply energy minerals, as glucose ATP and Figure blood t he capillaries for t he transpor t of absorbed liver lacteal for absorbing lipids and transpor ting t hem into system. ows liver. absorbed t he very villi contain network t he triglyceride reach substances cells. t he many has t hat soluble in of is section transpor t lymphatic system ileum vertical away villus blood which of acids molecules ● for uptake membrane active amino active much absorption epithelial cells surface epit helial for the The a ATP extensive, therefore into shows epit helial lacteal: can B.1.5.2 of supplies thick, diagram cell ● cell away of from vessels When a t hat meal molecules, vitamins. B.1.5.2 The absorb molecules. t he carr y has such These blood t hat in you and t he t he from t he glucose, acids travel enters reached as lacteals fatty ileum hepatic most small amino can see glycerol t he acids, in t he t his minerals centre are vessels vein, digestive intestine, t hat lymphatic of por tal of t he reformed and blood and into eventually blood. 81 835292 CSEC HSB Unit B Topic 1.indd 81 08/01/2015 16:03 Absorption 0 and the fate of digested Nutrition products Assimilation Key term ! The products used Assimilation Use of for t his. amino acids the to body, make glucose store fatty as acids e.g. glycogen and are used such as in t he t hose body. given Assimilation in Table B.1.5.1 is t he term become in t he body – t hey become par t of us. using proteins, q store digestion food assimilated in molecules of Substances T able B.1.5.1 Assimilation: fate of absorbed nutrients and glycerol as fat. Absorbed Fate of absorbed nutrients in assimilation nutrients Amino acids • Transported • Some are made enzymes • Excess into Fatty and acids glycerol Large Before trace small t he in stomach Excess • Converted the hepatic through glucose into is Absorbed into the this drains • Triglycerides t he absorbed. lacteal, into stored large food quite of are t he t hat for most the a and in portal vein and to liver. go to all repair, collagen the substance in the liver body and cells globular where they proteins, e.g. skin. to form ammonia, which is urea. to the travels glycogen which the long around liver. to and all cells stored for in use the in liver respiration. and in muscles. of the vital organs turn When and lymph system, by diffusion. stream. for, it e.g., t he to from and have protection. rectum) B.1.4.2 Food t he most no and and Figure ileum. passes molecules appendix insulation colon back leaving nutrient caecum part caecum, af ter time. is blood intestine takes useful The e.g. liver (appendix, about growth the and triglycerides. Eventually read toxic converted • intestine been less to liver deaminated the • pat hway colon does vein • in passes for proteins, are vein the ileum of and stays t he specic in t he into water functions humans. The hepatic you caecum have Transported Some portal through proteins acids into • hepatic pass brous amino • intestine t he the new and converted Glucose in molecules not Many which have bacteria producing other has villi live in vitamin harmful three like K the the colon, and bacteria sections small the from absorbs intestine which B-group growing water as it digest is the vitamins and and not minerals adapted remaining (see causing page although for it absor ption. food, 65). discomfor t They or prevent disease. liver As more and more water is absorbed, t he remaining indigestible food, cells hepatic and portal tissues r ubbed off t he walls of t he intestine and bacteria accumulate vein to form faeces. released when The we dr y faeces are stored in t he rectum and periodically defecate. Liver The liver is t he largest organ in t he human body and has many different large intestine functions small Control of including some t hat are par t of assimilation and excretion. glucose intestine appendix The liver from anus t he Figure B.1.5.3 Blood flows from in the are and large hepatic being intestines portal absorbed vein. the to the is very glucose, and of blood glucagon sugar which under are instr uctions secreted While blood in rich amino in nutrients, acids, meals 79). Liver cells conver t molecules of by glucose t he into glycogen for shor t-ter m storage. Making proteins this such vitamins page polysacchar ide cells use amino acids to make t heir own proteins. They also make as and proteins for albumen minerals (see liver Liver vein concentration insulin the t he small t he hor mones rectum pancreas p controls t he for blood, such maintaining as t he brinogen for concentration use of in blood clotting and plasma. 82 835292 CSEC HSB Unit B Topic 1.indd 82 08/01/2015 16:03 Nutrition Absorption and the fate of digested products Excretion The body These cells use cannot molecules remove t he par t acid Breaking to respiration. by paracetamol, and cells t he that The is are are sur plus used par t of process as a t hese of to where from it is liver Liver cells excreted of excess removing deamination. passes requirements. source nitrogen-containing have bacteria such Liver Urea detoxication. of t hat but in t he cells par t into energy. amino t he and nitrogen- make of Liver acids each t he of blood t hese and is urine. toxins of Storage t he kidneys process as acids from substances produced acids wasted, amino urea t he down toxic been in of molecules. transpor ted amino not nitrogen-containing substance amino Any t he molecule containing waste store are and in not the been gut Example are of warfarin, broken down in broken down by these which substances is taken to the gut liver are or cells alcohol, prevent have in the dr ugs blood clotting. micronutrients store fat minerals, soluble especially vitamins A, D iron and for t he synt hesis of haemoglobin, K. Constipation Constipation have is difculty difculty wit h in bowel passing faeces. movements, may People suffer who from are constipated pain and swelling 0 Key term ! in t he abdomen, meals. This Examples will more of will for They rich more also some vomit. foods encourage water problem and in need bre peristalsis, help; dr ugs to have include so more vegetables, preventing known as dietar y t he laxatives bre fr uit in and condition. may help to t heir bran. Drinking cure t he Constipation compacted void from A condition faeces the are where difcult to body. people. Diarrhoea Di arrhoea in a liquid of t he is a condition form. The in body which can a person become is continually dehydrated passing quickly as a faeces result 0 Key term ! loss of rehydration. uid is put water in t he faeces. If is not effective, t his directly into t he In serious a saline cases drip it is may treated be wit h needed, oral by which Diarrhoea the bloodstream. faeces A condition released are where loose and watery. Food poisoning poisoning ● ensuring t heir ● ● can is be t hat keeping ies, keeping raw cleaning and ● ● ● t hose ● common cause eliminated involved cockroaches, meat separate cooked working af ter in of diarrhoea. The chances of food by: t he preparation of food regularly wash rodents from meat surfaces cooked (see and and Figure kitchen ot her meat animals to away prevent from raw food meat from B.1.5.5) equipment t horoughly before use cooking meats t hawing frozen excluding food ver y hands cross-infecting ● a vir tually and meat food known products t horoughly carriers of t horoughly before food cooking poisoning microorganisms from t he industr y motivating p kitchen staff by means of a good working environment Figure B.1.5.4 spread easily bacteria chickens are kept and in adequate Salmonella when large numbers like this wages. 83 835292 CSEC HSB Unit B Topic 1.indd 83 08/01/2015 16:03 Absorption and the fate of digested Nutrition products Figure B.1.5.5 shows how someone can become infected wit h Salmonella. 1 2 carrier: contaminates chicken feed person: develops Salmonella food poisoning 7 infected may chicken or eggs: result poisoning meat: in food other if eaten remains undercooked infected with 6 Salmonella a result as of undercooking 3 4 butcher: infects from other meat infected chicken 5 p Figure B.1.5.5 inadequately practice. Salmonella cooked. Chickens Salmonella food food Notice kept in poisoning It poisoning how food battery can can cages also possible 2 3 but given is a eggs are Chicken Flies from likely to drinking hard eating by be chicken, pathogens infected unpasteurised to meat chickens of trace is t he of ten a by eggs or through meat animal Salmonella than which feed have and been abattoir free-range chickens. milk. source likely of an source. infection The of t hese diagram shows a cooked become contaminated, maybe by someone chickens properly eats t hem. babies, t he and t hen Most some bacter ia at elderly bacteria r isk and may are pass sur vive people anyone into t heir and wit hout who is eggs. can a strong already ill for reason. meat may processing can – can bacteria. t he who system are t he infect not ot her bacteria 5 to anyone immune meat be carrier bacteria some more from chicken Feed The results contaminated scenario. infect 4 are result who If be sometimes bacteria, 1 often can have factor y, transferred transfer bacteria. market to bacteria ot her to If or conditions butcher’s meats and in shop meat a slaughterhouse, are not hygienic, t hen products foods. 84 835292 CSEC HSB Unit B Topic 1.indd 84 08/01/2015 16:03 Nutrition 6 Undereating Putting 7 uncooked result in bacteria eaten wit hout Anot her bacteria being source and chicken next transferring of t hen to to ot her foods foods t hat are in a refrigerator taken from t he and overeating may fr idge and cooked. infection not is cooked eating meat t hat is contaminated wit h properly. Questions 1 State six features 2 What are the of the ileum that make it suitable for absorbing food. p digested end products of a proteins, b fats and c Figure in which can then be absorbed and B.1.5.6 meat processing of a 4 What 5 What is happens Explain food constipation? how to b amino someone What acids may they infected are a Undereating metabolic person is lying with Salmonella and suffer from and overeating Learning the end we down are and totally doing not hing, relaxed, we are he or still she will breat hing, still our beat, and absorbed, blood still of outline ows around ner vous t he system is whole still body, active food and, at is being t he the being topic you made and ions moved across cell of energy by body digested cellular surface to: uses human define the terms basal level, metabolic are this able use ● t he be hear ts the still outcomes rate ● When proteins the food should energy. reduce contamination assimilated? By If Salmonella poisoning. B.1.6 Basal of diarrhoea? is when be conditions plants assimilated? chances 3 Hygienic starch rate and membranes. malnutrition All t hese processes require energy. ● The energy t hat we use at rest is our basal metabolic rate (BMR). explain protein energy However, malnutrition ver y few, if metabolic any, rate people for t he are totally whole day inactive is much t hroughout more t han t heir t his. life, The so t he energy ● distinguish and we need to consume carbohydrates and to maintain proteins in our our metabolism diet. These is provided substances are by lipids, respired energy t hat is used to make ATP, t he energy currency of ● explain energy needs are affected by many factors such cells. ● age, younger people, on average, require more causes of determine ● ● whet her we our of level body ● mass gender – females ● are physical – larger males of t he quantity ● our and the In 3 have individual addition, mont hs require a of energy t han older an energy size and of explain the effects – constitution extra of human on the body. who energy requirement wit h less – on equal energy are people t heir t han about levels is of smaller 10% people more t han activity needed if it is warm of who energy. var y considerably in t heir energy physiology. pregnant Women intake more clot hing depending pregnancy. large mass people not need conditions women body activity quality requirements or people same environmental ● growing risks (BMI) malnutrition ● and obesity as: ● ● the health index Our anorexia bulimia to to release between t hat require choose extra to energy breastfeed during t heir t he last babies p Figure is used B.1.6.1 to metabolic Equipment determine like this people’s rate 85 835292 CSEC HSB Unit B Topic 1.indd 85 08/01/2015 16:03 Undereating and Nutrition overeating The energy needs of values q are T able T ype only B.1.6.1 of 1 year Child 5 years 12–15 Boy food of Approximate kJ daily per years 16–19 measured are in listed kilojoules in Table (kJ). The B.1.6.1. total Note energy t hat t hese approximate. years 12–15 is people baby Child Woman by types person Newborn Girl provided different energy requirements day different types T ype of 2000 Ofce worker (adult female) 3000 Ofce worker (adult male) person 7000 Heavy Full-time athlete (female) Full-time athlete (male) 8500 manual Pregnant of kJ 9500 11000 years of per day 9000 11000 worker woman people. 15000 (last 15000+ 20000+ three 10000 months) Man 16–19 years 10000 Written Energy Dr in a found diet period typical q carried She their of of T able Family breast-feeding 11000 Activity needs Sharma family. Woman and a out out investigation much compared week. their an how The usual this family diet. with said T able into energy the the nutrition people energy that B.1.6.2 the the they food shows in an extended family actually they her of the ate should consumed that week Daily energy needs/kJ Mother Father 7-year-old per Average day daily intake/kJ per energy day 9300 9250 10500 13500 3800 3300 Baby 5800 4250 13-year-old girl 9100 9150 15-year-old boy 9600 13050 9105 7000 1 State 2 Plot in 3 Dr child pregnant a the three bar and chart i Who ii Explain iii The What factors sister that that decided advised in the influence shows not would that them family why family would 4 younger the a person’s daily energy energy needs needs. of the different people family. Sharma risk was results. B.1.6.2 member Mother’ s have over you told to do Dr say their the the family some think she Sharma to of make you think change you some Dr made that eating family may changes Sharma these none of be to putting their their health at diet. identified as being at risk? decisions. them was ill and that they habits. to support Dr Sharma? 86 835292 CSEC HSB Unit B Topic 1.indd 86 08/01/2015 16:03 Nutrition Undereating Tr y this Calculate Find out overeating yourself your how and energy much intake energy for you a day consume during a day. typical Requirements ● a ● access to energy content T ake photograph 1 camera one a day. or Y our exception 2 Find the or 3 out weigh this of of of different laboratory ● balance/kitchen scales the foods each meal, must include much the how want photos about of to energy food much or you items before information who take photos them out to snack and drink everything that you you ingest have with during the water. how mass Find phone information you so eat energy you ‘watch consumed. the First, information you printed need on to the know packet them. each can their have use use food one calories’ item of the provides. apps Many designed and/or lose weight. serving and energy websites for have people These have lists of 0 ✔ foods 4 Y ou and can the also energy work content out how per much energy you have per used 100 grams. during the The day. is Keep a diary of the different activities you have done, such as down, walking, running, and how long you did each over 24 can find and add them out how much energy people use in each of used is is Choose suitable your calculate ways to present photographs the of energy that people. these to 4.2 needed kJ to and raise is the activities of 1 kg of water by up. 1 °C. include unit many equivalent energy temperature 5 a by hours. the Y ou calorie still tip sitting, It lying Exam energy and content all the of the information sources food and of you collect. information how much you energy Also used you unit to it The of calorie energy used in this is so not will you book the or in scientic not see exam papers. used. Malnutrition Malnutrition simply mean is t he t hat result t here of are a lack of nutrients balance missing in t he from diet. t he This diet, does t he not term covers 0 Key term ! bot h too overeating much healt h and energy from or undereating. too much malnutrition. fat. For an An unbalanced There adult, are diet many can serious consuming less be one wit h far consequences t han 5000 kJ for per Malnutrition Having provides more much day eventually leads to deat h by much less energy or a diet energy that or nutrients than star vation. required. A shor tage to or complete starvation. t he BMR wit hout to stores t he of and how much If adapts t his long tissues are t hey and by as food of water, sources protein for do about on activity how has down to t hat extends star vation, people conver ting lasts broken of Some have depends physical lack periods energy. protein energy body respiration; but save food. glycogen During have t hen of not over body sur vived t heir energy. t he bodies People sur vive as stores a in for can who long. glycogen a As t he period adapts up use do Fat provides energy much fat is how leading done. to stored, Lastly, body protein days stores of have into cold in leads 70 not for time reducing star vation liver day. be to of by proceeds glucose much it fat, good is and muscles for longer, how and ot her wasting. 87 835292 CSEC HSB Unit B Topic 1.indd 87 08/01/2015 16:03 Undereating and Nutrition overeating Protein energy Protein energy protein and protein it is a PEM are energy. for t hat energy mostly marasmus symptoms Those malnutrition total can disease of wit h malnutrition (PEM) When so t hat affects and is marasmus are it not is young not used for Exper ts to t he adapting a t he children. adapting are by happens kwashiorkor. kwashiorkor caused t his diet two believe all lacks bot h metabolises growt h The limited at t hat body and repair. extreme t hat what children availability This forms of of wit h food. well. Marasmus Children body is There a wit h ver y is little wrinkled and have marasmus t hin wit h muscle or fat appearance. no loss of have a shr unken, especially and t hin a wizened, However, emaciated arms t hese and legs appearance. (see old-looking children are Figure face. usually The B.1.6.2). The skin has mentally aler t appetite. Kwashiorkor The little boy in characteristic p Figure B.1.6.2 This girl is circumference of her upper from to severe marasmus, causes show a loss that she malnutrition. disease of tissue of is She legs can t his swell means children that reddish of ten Some for of hair. reasons people t hey of ten If food who t hat 15 is by a over to and a at if by doctor see is Some a 3-year-old condition the belly boy in which to swell. a severe drought he been living on hardly a any very fibrous nutritional is t he make not lifeless a well to star vation. swollen much drain ‘moon have less water face’ ver y The abdomen. protein from and little Sometimes for t he blood t he dr y, tissues. brittle These and appetite. one Most to a female. someone exper ts tackle way. are to so (deliberate) vomiting. It is an unbalanced estimated of t hem t hat are diet 85–90% young, ver y condition might laxatives develop of enough as a means be years combines stay wit h exercising intake, af ter a unhealt hy ver y is quickly, called to dangerous, is healt hy meal at or while t he t he person same time date. to keep repetitive followed bulimia. even by encouragement while vomiting an serious, obsessed encouraging like be of t hough anorexia counselling reasonably involves been food even wit h extremely many has into can can food life condition problems, eat someone problems to t heir or little usually t heir not t hat spend frequently about quantities does life. enough what This adopt Many agree underlying eat strict can eat Treatment Therapy using healt h t he t he explore This of person weight. dietician to area enough, fatal, food age. where food. large various of of understand. are t heir tr y down. to disorders to soon t hem hard plenty least not or to subconsciously, t hey It by is expensive t heir cycle of eating induced accompanied and time- has consuming with of ten abnormally by Following does liver, access years to t heir people weight have 30 under why enabling causes blood of ten condition treated Even t herapy kwashiorkor, children swollen are are access psychot herapy malnutrition These t he a eating and chooses, not fatal. has t hat have wit h have control This adapting disorders Anorexia B.1.6.3 too. They people between Figure not wasting Eating p is kwashiorkor suffering has starvation and of arm and measured B.1.6.3 having t he the Figure symptom palm value at and may r uin self-esteem. fruit all 88 835292 CSEC HSB Unit B Topic 1.indd 88 08/01/2015 16:03 Nutrition Undereating and overeating Obesity Too high cause us weight t han an to for 30 his is Obesity energy put or said is a on intake her to be form height of excess or who malnutrition nutritional disorders world t he to Someone carbohydrate who has is a 20% body and above mass animal t heir index fat can recommended (BMI) greater obese. par ts of due weight. affecting t he and t he numbers of is one people people of of t he t he wit h most common Caribbean. obesity are In many increasing. p Figure a BMI is used to determine t he relative weight and nutritional status whet her obese, healt hy or under weight. is calculated using t his matching among of BMI A woman therapy with session anorexia. for She of is individuals B.1.6.4 young a photograph several women. outline Many of herself drawings people with formula: anorexia have a poor body image of themselves Body BMI mass (in kilograms) Height (in metres) = 2 As you and can 24.9 see are in Table B.1.6.3, considered most people wit h healt hy, a while BMI if a ranging person’s between BMI is 18.5 higher 0 Key t han Obesity 25 t hey are regarded as T able B.1.6.3 overweight International and classification according obesity BMI medical to of adult people overweight underweight, BMI index or greater are condition 30% have than a or in more body mass 30. Category Less than 18.5 to 18.5 Underweight 24.9 Acceptable 25 to 29.9 Overweight 30 to 34.9 Obese (class 1) 35 to 35.9 Obese (class 2) Over 40 Source: Severely Centers Individuals conditions hear t for Disease wit h and disease, a Control BMI Prevention exceeding diseases, varicose and such veins, obese as 29 (class (2009) are classed hernias, strokes, 3) as ar t hritis, diabetes, and may be at risk hyper tension, prostate cancer (in of coronar y p Figure effect men), the and A over weight. which q term ! cer vical There are Fir stly, diets a a spend in Even a help to is people may an The be factor s in a fatty low and t hat have traditional foods fibre an of led and decrease refined an in food levels an of rat her working obesity diet Secondly, transpor t people to high-fibre content. public number action of is serious rotting stomach side teeth acid on from enamel in to so wit h epidemic. called high increase physical t han ‘ Wester n’ sugar in income activity walking. occupations wit h Finally, t hat to a require work . who are weight lower Height could t he small of One bulimia women). Thirdly, car s physical Individuals ot her. r ic h food. (in from wit h using decrease muc h are and on people var iety c hange t hat content cancer B.1.6.5 of t he considered loss risk of impor tant have taller t he (just of developing factor same person obese 10% in body may are t he recommended individual’s diseases associated determining mass, have a but if one normal a BMI, lose wit h person may to current be is t he will obesity. healt hy. much while weight. weight) taller shor ter Two t han t he person obese. p Figure B.1.6.6 problem in the Obesity is a growing Caribbean 89 835292 CSEC HSB Unit B Topic 1.indd 89 08/01/2015 16:03 Undereating and Nutrition overeating BMI to values degree In are differences of recent years, BMI of lower in t here limits t hat t he 25 and t han has for been a over is same may growing different differ t he BMI for not bot h sexes. correspond However, to t he due same populations. associations distribution and propor tions, different BMI evidence fat body fatness different body age-independent in et hnic between across debate groups. BMI, a person t he is This still need of means might to develop increasing percentage populations. ‘over weight’, over There be body t hat at risk fat and alt hough wit h a a BMI t his. BMI 32 30 28 obese 26 24 e o o i s y t b f k s 22 r a i t e n 20 a g a r l m r o n 18 16 14 12 10 2 3 4 5 6 7 8 9 10 11 Age p Figure B.1.6.7 Graph Written Children There is and take the growth q charts is age help B.1.6.4 into to BMI weight T o how see then body really is lose this not much trousers to weight, have but needed in the first B Topic 1.indd a 17 index 18 (BMI) interpret are 19 20 and age to and the less use growth Control 5th up or and a to the the equal to for T able variation of in the it for overweight is necessary boys or and obese to girls. or The not. percentile 95th look B.1.6.4 and to at which at two be age growth questions patterns each can the answer growth children mass percentile (2009) children, size healthy body charts percentile the Prevention with assess 85th 95th data to is children. percentile BMI samples child in because children than than obesity children whether for about for together used of countries percentile 85th Disease them wide age of are shown charts 1 and children. recorded. on 2. The This (see page 290 for an example of a histogram). This histograms population for is much known easier to use 16 possible each to for masses reveals It than Greater Centers Percentiles B.1.6.8 decide 5th overweight Source: and many account Less of 15 complicated Underweight risk mass categories Overweight Figure in more BMI Healthy p body Category At 14 Activity concern BMI child’s T able 13 BMI great Interpreting of 12 (years) this size as the reference population. of place 90 835292 CSEC HSB Unit 90 08/01/2015 16:03 Nutrition The Undereating body mass population of whose body greater than less A than child of be a mass 25% 75% whose children of in child children of is of at body is compared the the the the the of 25th 16-year-old mass is the For percentile, reference sample to age. same over the population in that 95% of the of mass the reference 16-year-old that is 16-year-old the girls; girl same she as or weighs population. percentile weighs same and age is more than 95% considered to BMI –2 –2 kg m m 34 34 Body mass index-for-age Body percentiles: mass index-for-age percentiles: 32 32 Boys, 2 –20 -. · + 30 Girls, years . . . ..· "-~ 30 l V,., . . , . , -+- r H 24 26 ..... .i ).e" 90th , 85th , 75th i), • ~~ : fH+ ~ . i-,, t;.~ ~ + · 20 10th .... -:r ~' ... i: 50th 25th ~ 25th ~ ":;? 5th 18 ,,, . 18 ;:;:~ ~ i,~ ~:, _., ~ l:Ht ~ 16 . _:.. la> t :r t • :.L ...... CT . ! tt . 1.1 +. 12 H+ 12 4 6 8 10 12 Age Figure Chronic 5th 14 ~ Source: 10th HJ: ~ 16 :f tt .c ,.• " 2 I 22 ,;..~ ~ ,/ . ~ 20 14 +iri:+ + :t . .,. 50th 95th . ~ .1 H. ...l 75th 24 I:t :t: . . t 22 85th l! /.~ years :+ . f . 90th 28 26 2 – 20 95th 28 p a in a B.1.6.9 National Disease 14 16 18 .. ~ t 20 2 4 6 8 10 (years) Growth Center for charts Health Prevention 12 Age and for boys Statistics Health in and 16 18 20 girls collaboration Promotion 14 (years) with the National Center for (2000) 0 ✔ Questions 1 A doctor 23. Use calculates the growth the BMI chart for for four boys 10-year-old in Figure boys B.1.6.9 as and 13, 18, T able 21 Making and B.1.6.4 Study the to the BMI categories for the four girls of different ages each have a 13 and 16. What advice would the BMI of 24. The girls’ ages the answer by reference to the doctor growth 3 T able Suggest to summarise malnutrition the form give to the chart for girls in effects girls? Explain Figure B.1.6.9 to (pages and of of will all help on the malnutrition body. Don’t are mineral your table match forget 10, tip boys. with Three a forms you determine 2 overeating overweight. BMI kg has population girls variation example, and include the deciencies 64 and vitamin from and Unit B.1 65). B.1.6.4. two ways in which parents contribute to their children becoming overweight. 0 Talk about ? Discuss with The World the world’s bulimia, make Health family, have friends Organization greatest can sure your health very people eat and has threats. serious teachers identied Eating effects on the the statement obesity disorders, young epidemic such people. below. as as one anorexia What can be of and done to properly? p Figure B.1.6.10 sedentary energy the ways content obesity Lack of … of life, all exercise, foods factors with that high fuel epidemic 91 835292 CSEC HSB Unit B Topic 1.indd 91 08/01/2015 16:03 Undereating and Nutrition overeating Questions 1 What is meant 2 Define 3 What is the cause of kwashiorkor? 4 What is the cause of marasmus? 5 What causes 6 Calculate 7 Identify 8 Give 9 Describe a balanced diet? malnutrition obesity? the BMI three three Discuss uses of is man of 1.73 m, who with associated weighs 70 kg. obesity. BMI. the dietary advice a nutritionist might give to an obese. health the a explain who Caribbean for diseases and individual 10 by risks countries associated with overeating, especially in the today. Summary Nutrition ● A balanced out. Energy and fats. cells ● The is The and provides provided diet tissues, essential ● diet fatty must acids in water; Vitamin A is gums, also for are provide essential making for for B energy A, D, vision, for all macronutrients cell vitamins vitamins needed vitamin the including micronutrients soluble enough by molecules acids minerals. and K vitamin respiration, activities we carbohydrates, for carry proteins for building making proteins and membranes. and E biological amino the – are C vitamin for D Vitamins fat making for B and C are soluble. collagen absorbing and in skin and depositing 1 calcium ● T wo for ● bone. minerals that transporting The q in table T able Food need to oxygen, shows the be and tests in the diet calcium for are for iron for making strengthening identifying food haemoglobin bones and teeth. substances: B.1.6.5 substances Biochemical Proteins Biuret test copper Starch Iodine – test sodium sulphate in hydroxide solution and solution potassium iodide solution (iodine solution) Reducing fructose, sugars, e.g. glucose, maltose and lactose Non-reducing Lipids (fats Vitamin ● Water and urea e.g. sucrose is Positive result with oils) Emulsion required in the in the gut by transporting many other body as a hydrolysis blood useful sugar, and as for the DCPIP test after acid solution breaking major hormones, waste s Benedict’ test solvent, and with hydrochloric Decolourising for and solution reacting C molecules plasma sugars, Benedict’ s down food component carbon dioxide, in blood salts, substances. 92 835292 CSEC HSB Unit B Topic 1.indd 92 08/01/2015 16:03 Nutrition ● ● Undereating Dietary The fibre cause symptom of bacterium in ● the prevents of many food leads children quantities ● Body of in to in against the including bowel diet. food poisoning cancer. Diarrhoea poisoning is but in a Anorexia often is by poor it by variety and with of with are a the hygiene dividing T wo result of young extremes their or even as vomiting. mass are disorders reduce such body the lack mostly eating normal measures, by affects anorexia eat is complete ways. bulimia bulimia extreme calculated Obesity A malnutrition People people is required. energy women. lose (BMI) undernutrition. than starvation young food fibre food and food Protein marasmus. index of protects of disorders overeating considerably; mass and lack cause energy respond and mainly intake The the overeating food. starvation. who affect food more to kwashiorkor that of includes consuming is intestinal Salmonella. preparation Malnutrition of constipation constipation and in large kilograms 2 by ● (height The first in set permanent into ● food Each The ● and the embedded living the such activities Regular Enzymes are speed is feed to brushing to is are replaced incisors that enamel pulp tooth These are molars hard the leading as teeth. teeth chew that cavity above full the and food a cells, gum, the that bite (mastication). covers of by canines softer blood the root dentine. vessels is the and part of bone. teeth visits the water proteins up the As over the on sugar tooth teeth and at least are convert Decay decay. dentist and such into as the twice to acid be day and a essential it can in which breaks prevented using identifying by dental early stages 10°C the activity of affects Pepsin extends pH into over below or activity enzymes 37°C. of excess activity a into the range associated intestine biological without end of a catalysts being used reaction the breakdown triglycerides. water of soluble The which up they catalyse This of large food converts molecules that large, can be rate body steeply rate from of of reactions low temperatures reaction occurs temperature. because they After are at the 37°C, denatured by 40°C. enzymes. stomach pH All has has with enzymes an an have optimum optimum enzymes being an pH pH optimum of of 2.0 8.0. denatured and pH. trypsin Activity at values of range. of mouth, (duodenum (colon, is The steeply maximum 37°C, consists organs: enzymes. increase intestine of this system intestine of small above and the and small of digestive large proteins into decreases The small to the at catalyse enzymes secreted secreted enzymes in the are again. the temperature temperatures pH up They reactions blood. human as cells. unchanged starch, affects such by chemical molecules catalysed optimum are over T emperature by of system, insoluble absorbed made rate they digestive molecules ● and the in of decay. reactions ● on enamel floss. In of milk with tooth crown themselves. ● premolars of The the types centre tooth that ● is The covered Bacteria of teeth is down ● of teeth. tooth nerves. the metres) and rectum, the main salivary ileum), regions glands, of the alimentary oesophagus, pancreas, liver, gall canal stomach, bladder and anus). 93 835292 CSEC HSB Unit B Topic 1.indd 93 08/01/2015 16:03 Undereating and Nutrition overeating ● The mouth moves is food to contraction. acid ● The to kill small surface stores ● Villi are lacteal ● The absorbed until by pepsin of food. they peristalsis, secretes adapted to for many The are digestion, start large passed in epithelial cells with each villus the of in of the excess amino the (adipose) Egestion excretion is acids glycerol products are stored body; body: converted and of digestion Glucose organs is transport in amino the liver cannot to are urea is be and acids waves it digestion has a very supplied absorbs the muscular by of by blood to water and defecation. increase capillaries protein. large remaining anus which many of hydrochloric the and one digestion. are are stored so into into in the the body liver or synthesised used excreted recombined well has glycogen they as through assimilated as are containing microvilli, of oesophagus chemical intestine out absorption; for the and area for juice absorption villi the which gastric covered everywhere ● and is composed products acids mechanical stomach bacteria absorbed. which for stomach intestine faeces surface the The area transport adapted are to after is into make through the into kidneys; and are proteins plasma deaminated triglycerides they respired in all proteins; ammonia, fatty stored in fat tissue. is is the the removal removal of of undigested waste food products from of the large intestine; metabolism. 94 835292 CSEC HSB Unit B Topic 1.indd 94 08/01/2015 16:03 Nutrition Practice 9 Practice From t he table below, features which best Questions describe Questions enzymes? Section 1 A Which of t he following is a list of fat soluble Biological Contains Affected Affected catalyst active by temperature 2 A, C, B B, E, C A, D, E, D B, C, D Which D, pH by vitamins? A A sites û ü ü û K K K type of teet h are responsible for most of B û û ü ü C ü ü û ü D ü ü ü ü t he KEY mechanical digestion in t he mout h? = YES = NO ü A incisors û 3 B molars C canines D premolars The 10 A of of salad which to your diet can help in t he following is an example of a A cellulose B starch C glucose D maltose t he disease? constipation B rickets C diarrhoea D anaemia Section 1 4 of monosaccharide? addition prevention Which The biuret colour t hat test change which of is carried from t he out blue to on a sample violet following is of seen. nutrients is milk. This B a Define b Malnutrition t he term can balanced overeating. Complete diet [2] A be caused by undereating and indicates i) t he table below about under present? nutrition. A sugar B starch C fat D protein Nutrient Vitamin Deficiency Nutrient Disease food source A Anaemia 5 The enzyme amylase is found in our digestive tract. Kwashiorkor Which pH A pH 9 B pH 3 C pH 5 D pH 7 does t his enzyme work best [5] ii) Obesity by is an Someone t he lacking vitamin C in t heir diet can healt h deformation in t he weakness C night c Identify Harold bleeding Marasmus is A lack carbohydrates B increased of a condition due to D of t he two factors obesity. ot her t han diet t hat can a [2] chocolate determine if fats muffin (lipids) for are breakfast. present in He his Write a list of steps for t he procedure to test [3] a Distinguish b Explain between what excretion happens in t he and large egestion. intestines [3] of t he proteins increased of to lipids. digestive tract Our are for t he formation of faeces. [4] calcium cells i) All is iron c 8 which obesity t he: 2 lack caused in gums for C wit h way [3] bought to muffin. 7 person disease blindness wants D a a one bones lead B of of Describe experience: iii) A example overeating. affected. 6 Meat at? following are conditions related to List made t hree up uses of of almost water in 70% t he of water. body. [3] obesity ii) Name two diseases/conditions t hat are caused except: by A coronar y B ast hma hear t a lack of Give t hree conditions diabetes D hyper tension in t he diet. [2] disease iii) C water signs or named symptoms in (c) (ii) of t he above. diseases/ [3] 95 835292 CSEC HSB Unit B Topic 1.indd 95 08/01/2015 16:03 Practice 3 We Nutrition Questions need to balanced only t hree a i) eat diet a is balanced made undergo t he diet of for us different to be healt hy. nutrients of A which a Name b What digestion. Complete products up t he of following digestion bloodstream. table t hat are about t he absorbed c into d B? What t he End product of is Delroy A to name D of on t he t he diagram. enzyme [4] released by t he par t [1] above? t he Nutrient par ts t he labelled b [3] t he is function of t he enzyme named in [1] had blank a slice spaces of in fish t he as par t diagram of a meal. below Fill which in shows digestion stages in t he digestion of t he protein in t he fish. [6] Carbohydrates Proteins 1. Mouth: Teeth crush 2. Stomach: 4. Small Enzyme___________ Fats and grind smaller ii) Name two balanced each. b Food i) ii) diet nutrients and give a present food in source into pieces. a for [4] prepared hygienic ot her food for consumption must be done under conditions. Make a when preparing list Diarrhoea infection hygiene two of is in 4 a hygienic food. condition t he during gut by food practices a caused vir us by due preparation. signs/symptoms to PROTEIN follow [4] of t his an to poor Suggest disease and 3. two Small the measures of treatment t hat can be taken. Intestines(I): ______________ enzyme juice contains _____________ polypeptides to diagram below shows t he human alimentar y contains __________________ peptides. The juice the that [4] converts 4 intestines(II): Intestinal e The digested from the the materials alimentar y bloodstream. allow 5 to _____________________. canal. Samuel them ate a to of the canal State absorb hamburger protein through THREE features digested for are the of materials lunch at absorbed villi and the into villi that quickly. [3] school. B a Name two b Explain how teet h his in major Samuel’s toot h to i) t he are different involved brot her for t hey toot h of present in his types in meal. [2] of mechanical [4] little ac hes dentist, each mout h digestion. c nutrients some found Keron time. out has Af ter t hat been having c hec king Keron had a wit h cavity a due decay. Describe t he process of toot h decay. [5] A ii) Make a follow list to of care four for guidelines his teet h for and Keron prevent to any D ot her cavities. [4] C 96 835292 CSEC HSB Unit B Topic 1.indd 96 08/01/2015 16:03 Unit B The B.2 B.2.1 The exchange respiratory (gas structure of the exchange) breathing and gas system Learning system By the end should Are you a rst aider? If you are, you will know what to do if someone in an accident and stops breat hing. You should also know of this able topic you to: is ● involved be outcomes explain the importance of why breathing breat hing out expired air into someone else’s lungs will help to keep ● t hem alive. This chapter deals wit h t he impor tance of how we relate the breathing and what happens to t he oxygen t hat t he trainee rst aiders structures of system their the breat he watching to t he functions demonstration in t he photograph may one day have to provide. ● distinguish breathing, Structure of the respiratory (breathing) between gas exchange and system respiration Breathing is t he exchange of surface t he ow oxygen of and air in and carbon out of dioxide t he by lungs. Gas diffusion at exchange t he gas is t he ● explain vital In in humans, lungs and nasal cavity: small hairs cells stale dust also moistens and a air rich carbon in is in fresh, t he lungs, par t oxygen-rich dioxide, is air removed t he from to leading capacity. our into our lungs. of to tube middle ear good that warmed palate: nasal closes opening when swallowing p Figure B.2.1.1 demonstrates closes A first mouth aid to instructor mouth larynx breathing when by respirator y brought Eustachian soft epiglottis: meant air; so is of is opening bacteria; very supply inspired surface ensures goblet mucus) trap blood air, exchange which contains (secrete contains gas system and is lungs. t he (breat hing) what exchange – closing the nostrils and swallowing tilting back the head of the model oesophagus larynx: contains vocal trachea cords. When air passes Key over and them they speech terms ! vibrate results Breathing bronchiole bronchus diaphragm in and Gas left out of movement ribcage the exchange to of the move air lungs. The diffusion lung of rib oxygen between intercostal The and and air carbon and blood dioxide in the lungs. muscle alveoli pleurae: contain which cushions when breathing diaphragm fluid muscle lungs diaphragm p Figure B.2.1.2 breathing A vertical section through the head and thorax showing the system 97 835292 CSEC HSB Unit B Topic 2.indd 97 08/01/2015 16:05 The structure of the breathing and gas exchange The The system terms respiration remember t hat and breat hing respiration is t he are respiratory of ten process t hat (gas confused. occurs exchange) You inside system should cells, oesophagus no cartilage reduce to t hroughout t he glucose fat). and to release Breat hing is energy t he ow from of air nutrient into and molecules out of t he (mostly lungs friction brought with body, about by movement of t he diaphragm and ribcage. oesophagus cartilage: Breat hing supports trachea is also in in is known t hrough also as t he known as expiration mout h inspiration and and/or and exhalation. nose, passes inhalation; Dur ing t hrough breat hing inspiration t he t hroat air out ows and lar ynx lumen and to inner lining into end in dust tiny air ways poc kets, t hat called extends alveoli. into You t he can dept hs trace of t his t he lungs pat hway in B.2.1.2. bacteria Figures trapped; cilia beat to B.2.1.2 plus debris B.2.1.3 Transverse the B.2.1.3 t he show head and t he str uctures t horax t hat (chest). are The involved upper in respirator y tract oesophagus as far as t he lar ynx; t he lower respirator y tract extends from t he sections top through wit hin upwards extends Figure and drive breat hing p air of epithelium; and mucus system of Figure ciliated a and of t he trachea to t he alveoli. Table B.2.1.1 describes t he str ucture and the functions of t he par ts of t he respirator y tract. trachea q T able Name Study ✔ B.2.1.1 of part Figures and T able names B.2.1.2 B.2.1.1 and and functions of the human Structure respiratory Function(s) and to functions learn of Made the of nine muscles; B.2.1.3 Trachea A wide rings these tube of pieces contains of the stiffened cartilage vocal by and Vocal cords in the gas vibrate and produce sound cords C-shaped Allows cartilage air bronchi. to ow from Cartilage C-shaped structures tract tip Larynx Use Structure ring throat holds allows the the to tube open. oesophagus exchange behind it to expand when it carries food system. (see Bronchi T wo branches surrounded for Bronchioles of by the Allows trachea blocks of (singular: air to ow in thin tubes branching from the Allows air to ow between Blind-ending air sacs. a of thin single layer by Lined cells blood Gas by exchange diffuses and dioxide capillaries alveolar goblet The diaphragm out of of t he tissue; t he ribs The Ciliated separates t he lungs. it is to t he t horax diaphragm The central surrounded t he t he bronchi B.2.1.4). by sternum. move trachea, Figure B.2.1.4 of and contract Figure of each bronchi and from t he from occurs air diffuses to here blood; from – oxygen carbon blood into the air abdominal cavity. cell Movements p out alveoli surrounded mucus-secreting and support Very alveolus) B.2.1.3) lung cartilage bronchi Alveoli Figure The par t t he of t hick up ribcage t he t he and t hat ribs are is air is a to joined t he ow tough to t he intercostal into and brous sheet backbone, muscles t hat down. bronchioles mucus-secreting cause diaphragm muscle Between ribcage and and are lined by a ciliated cells make sticky epit helium mucus t hat (see covers epithelium t he to epit helium. t he mucus. mucus ver y air along Gas from of par ticles cilia beat air ways way to of back and towards protect t he dust, t he pollen, for t h in t hroat. lungs bacteria a coordinated This against and vir uses way epit helium damage from to stick move provides par ticles a in t he infection. exchange Sections full The t he effective and Small t hrough air. Lung t he tissue lungs is like ver y t he one spongy in and Figure most of B.2.1.5 what show you t he can lungs see as lling 98 835292 CSEC HSB Unit B Topic 2.indd 98 08/01/2015 16:05 The respiratory t he upper t heir ver y right, can exchange) par t of t hin linings. which widen section (gas of have to a t he allow ventilates a when t he you you air to are sections two linings reach t hrough bronchioles t he so at during alveoli. t he t he deep The alveoli bottom ‘tube’ of the breathing t his fairly t he alveoli constant breat he breat he of process capillaries direction. oxygen t hat it in, air out oxygen oxygen around The t hat has Follow so t hat enter ing t he t he concentration alveoli and t he blood it can t he air of a inside is oxygen alveoli recoil t hat of makes little to occurs air in carbon into t he t he is constantly and carbon t hem help exchange a cross refreshed dioxide. enlarge a out time. During bit; some of owing lungs t hrough t he has carbon about blood dioxide t he capillar y into diffuses blood t he of opposite t he carbon total dioxide tissue. in owing t he in 70% carries respiring and enters all Figure passed B.2.1.6. is blood t hat has been pumped by t he hear t to t he t he alveolus. Figure Oxygen dissolves in t he lm of water lining t he B.2.1.5 alveolus. and tissue showing transverse bronchioles Oxygen diffuses down its t hrough t he cells t he t hat t he capillar y, plasma, and line t he cell alveolar sections and a blood through vessel lining surface t he t he blood Oxygen two (x18) alveolus, blood membrane of t he red red of tissue concentration gradient cells Photomicrograph lungs. lung 4 system and p 3 gas t hey push alveolus dioxide deoxygenated oxygen blood t he and ows This while dioxide from alveolus carr y. pat hway Deoxygenated carbon diffuses absorbed t he This 2 and wit h lef t breat hing t hird structure air. Exchange 1 are internal more to When There The vessel. Breat hing achieve photograph folded blood system blood cell cell. combines temporar ily wit h capillar y haemoglobin to for m oxyhaemoglobin. The movement oxygen red blood cell transpor ts oxygen to 5 in Blood t he is alveolus body. now movement carbon of dioxide respir ing the cells of into out of the alveolus fully saturated wit h oxygen 2 and 4 ows into a vein t hat takes blood from diusion t he oxygen 3 lungs back to t he of into diusion the blood carbon from Features of gas of hear t. exchange dioxide the blood surfaces cells The alveoli share t he following lining the characteristics alveolus wit h t he gas exchange surfaces of ot her ver tebrate animals. ● A ver y space large for surface molecules area of so t here carbon is plenty dioxide of and p oxygen t hese ● A to diffuse gases ver y t hat good oxygen and – are blood t his maximises exchanged supply carbon to dioxide t he volumes between maintain between air and blood B.2.1.6 Gas exchange in an alveolus blood. concentration t he Figure of and gradients t he air in for t he alveoli. Key term ! ● A lining A t hin t hat is permeable to oxygen and carbon dioxide. Deoxygenated ● lining, so t here is a shor t distance for t he molecules to has The lining of the alveoli is made of ver y thin cells that are similar to the cells about blood it dioxide that line capillaries. These two layers of thin cells separate air blood Blood that diffuse. from 70% can than of carry is in the and maximum more carbon oxygenated blood. blood. 99 835292 CSEC HSB Unit B Topic 2.indd 99 08/01/2015 16:05 The structure of the breathing and gas exchange The system The effect The composition from Table q t he of exchange of t he composition B.2.1.2 T able gas shows B.2.1.2 t hese of Inspired Oxygen % 21 Carbon dioxide Water % vapour alveoli you air on breat he t hat you the out (gas composition (expired breat he exchange) in air) of system the air differs (inspired air). differences. Comparison % the t hat t he Component Nitrogen inspired and expired air air Expired air 16 0.04 4 79 79 Variable (depends on the Saturated with humidity) evaporated T emperature Variable Warm Purity Variable Most Practical to air of in respiratory dust water from the particles vapour lining of that the has airways removed Activity disinfected Showing that expired air contains more carbon dioxide than inspired air mouthpiece Requirements ● apparatus ● lime ● dilute Lime lime p Figure B.2.1.7 apparatus for inspired and The of shown in Figure B.2.1.7 two ● solution water pieces sign turns of disinfectant milky when eye ● carbon dioxide is (+) of paper drawn on with each a plus one protection passed into it. water ‘huff and carbon expired 1 Sterilise 2 Put 3 With a a clip mouthpiece on your and nose or attach hold it to your the nose apparatus with your on the apparatus. fingers. puff’ comparing concentrations as water dioxide your several in mouth over the mouthpiece, breathe gently in and out times. air 4 In Observe which ask, breathing 6 Clean and A until or both and B, B as does asks you the have out the apparatus the pieces of breathe. lime water turned and refill paper it with turn milky rst? Y ou can continue milky. with the limewater, crosses sterilise drawn on the mouthpiece them underneath flasks. Repeat steps to breathe to disappear Record and 2, in Douglas are shown out in The student and the the the into the used an 4, but this time mouthpiece. tubes results A and you start Time a timer how as long it soon takes as you start for the cross B. obtain. 1 air to collect empty samples Douglas bag. of air. The In bag an investigation, was tted with a student ow valves diagram. breathed volume the skills of bags and both explain Composition breathed 3 through Maths as A place both 7 flasks of air out four inside in times the into bag the was bag. The measured. bag A was sealed sample of air 100 835292 CSEC HSB Unit B Topic 2.indd 100 08/01/2015 16:05 The respiratory from the bag (gas was exchange) analysed system for the The composition of oxygen, structure of the breathing and gas exchange carbon atmospheric dioxide and system air nitrogen. valve The student then the exercise, the did some student vigorous repeated exercise the for 5 procedure minutes. to collect Immediately a second after sample valve of air. The In both results cases of the his breathing investigation rates are was shown 12 in breaths T able per minute. air bag B.2.1.3. of q T able breathed B.2.1.3 for collection breathed breathed Sample of exercise out out air air air p Before out After Figure B.2.1.8 This student is filling a exercise Douglas bag with expired air 3 Volume of air/cm 2000 15 000 3 Mean volume of air per Percentage of oxygen Percentage of carbon Percentage of nitrogen 1 Calculate the 2 Calculate the Douglas 3 The 4 air Calculate Use figures samples to 15.3 3.6 5.5 74.9 74.7 in the air into table the per in breath the compared the student’s the calculate of change exercise moved volume. the volume percentage after of 500 17.2 dioxide mean bag volume breath/cm for minute the volume volume with lungs after in of air collected in the before. 1 minute volume percentage of exercise. oxygen is called before of and oxygen absorbed by the after in the the minute exercise. two student in 3 dm 5 per minute Calculate the before volume and of after carbon exercise. dioxide breathed out by the student in 3 dm In a the per separate air he alveolar ● air those Vital 14% the out breat hing air B.2.1.9 exercise. student air is carbon ● the percentages sample you is as in much as have using capacity in and t he just a breat hing not air much af ter is the This rst Vit al It out. after from collected the only alveoli. the The very last part composition of of his of of dioxide oxygen expired air 5.6% and that carbon he nitrogen ● dioxide are 80.4% different from collected. capacity Breat he move and was: why in before investigation, breathed oxygen Explain The minute is t he out tot al to can. you your is lungs volume of take a ver y Now breat he is your vital her vital capacity. out record This Now can. maximum fully. of you as breat hed meter in as air volume t he when your of air volume of as t hat air because can t hat as breat h hard capacity. breat hing lungs deep out The be can by you girl in can. Figure exhaled you deeply you as can as possible. never breat he 3 out all alveoli It is to a t he air. There is always about 1 dm remaining to keep your inated. possible band volume to record around of your p your your chest breat hing chest. are As you recorded movements breat he on a in char t by and attaching out (Figure t he a Figure B.2.1.9 Measuring vital capacity sensor changes in B.2.1.10). 101 835292 CSEC HSB Unit B Topic 2.indd 101 08/01/2015 16:05 The structure of the breathing and gas exchange Yo u The system can see from t he Figure B.2.1.10 respiratory t h at t he (gas p er so n exchange) b reat h ed in system and ou t 3 about 50 0 cm while breat hing n o r mally (t h is volume is 3 1 as t he height and 3 dm tidal volume) and t h ey 3 Note: It is age. p kn own Figure B.2.1.10 movements Volume recorded of over a vit al c apac it y of 50 0 0 c m 3 1dm = possible Such h ave 1000 to cm predict calculators a person’s are vital available as capacity based on t heir apps. chest time Practical Measuring tidal Activity volume and vital capacity Requirements 3 bell jar plastic (or large ● bell jar marked ● a ● three 1 Set up the scale. in dm trough ● tubing ● dilute solution of disinfectant wedges the apparatus as shown above, ensuring that the water level is on container) Sterilise the mouthpiece. 3 volume scale /dm 2 Record the initial 3 T ake 4 Measure 5 This 6 Repeat steps volume can volume. blow a deep breath then breathe out fully through the mouthpiece. here the decrease in volume in the bell jar. tubing 3 connected to is your vital capacity in dm disinfected water mouthpiece wedge free of to to 4, only this time exhale normally, so that the tidal be measured. water Ask p 1 allow circulation Figure B.2.1.11 measuring vital Apparatus capacity for and other capacity students and tidal in your class volumes. to Use use an the app to apparatus predict to their measure vital their capacity vital and see tidal how many match the predictions. Now try Maths skills 2. volume Maths Is there a correlation Researchers referred to age; sample q of T able BMI calculated they correlation in the a the BMI people vital North determined between the 2 between measured hospitals researchers and skills BMI and vital capacities American predicted the and BMI of vital are over for person vital 300 lung capacity each predicted investigated of city capacity? from to in each see capacity. shown people function T able if The who were tests. The person’s there is results height any for a small B.2.1.4. B.2.1.4 Vital of capacity/% BMI predicted Vital of capacity/% BMI predicted Vital of capacity/% predicted 50 61 35 95 20 96 56 75 30 85 22 130 45 90 31 98 52 77 42 84 25 82 27 92 43 102 24 110 38 75 1 Describe 2 Plot how these the results researchers on a calculated scattergraph with the BMI BMI on of the each person. horizontal axis. 102 835292 CSEC HSB Unit B Topic 2.indd 102 08/01/2015 16:05 The respiratory (gas exchange) system The breathing mechanism a 2 3 Do you think there the evidence for is a your correlation between BMI and vital capacity? Give answer. 3 Suggest the limitations 5 Suggest the problems of the that information people with a in T able high md / ria 4 B.2.1.4. BMI might have with their fo 1 emulov breathing. Questions 0 0 1 Refer to Figures B.2.1.2 and B.2.1.5 to list the pathway taken by 10 20 30 40 50 60 40 50 60 a time / s molecule of oxygen from the atmosphere to the gas exchange surface. b 2 2 Refer gas to Figure exchange B.2.1.6 in the to list the route taken by carbon dioxide during lungs. 3 Refer to are 4 What the 5 Distinguish 6 Some adapted role of the between students and for B.2.1.6 gas in the exchange investigated describe three ways in which exchange. cartilage gas to the trachea and and in the 1 emulov is well B.2.1.5 fo alveoli Figures md / ria 3 bronchi? breathing. breathing of a 16-year old male athlete. 0 Figure B.2.1.12a shows his pattern of breathing for a minute 0 when 10 20 30 time / s resting. took Figure some B.2.1.12b shows the pattern of his breathing while he exercise. p Figure of a Make a table to compare his breathing at rest and during a ● ● ● b in the volume the rate the volume of of the breathing when The air breathed breathing Calculate B.2.2 air in percentage he in takes with breaths breathed in each per resting change in a breat hing t hat exchange b 1 minute while 1 minute exercising each of Include these your aspects answers of in his the table. mechanism Learning the end outcomes of this topic you breathing mechanism ensures t hat t he air in t he alveoli is refreshed gases in t he lungs continues be able to: so ● of patterns a minute. should The athlete; breath By of breathing minute during exercise. breathing Mechanism The male table: the of old exercise. while Include B.2.1.12 16-year describe the breathing efciently. mechanism Movement high of pressure air during region to breathing a low depends pressure on region. the Air fact is that air breathed moves in from a ● outline the when than our chests expand. atmospheric This pressure so makes that the air is pressure pushed of by air the inside higher the our lungs pressure less ● rate explain of lungs. This so Air makes that is the some of breathed pressure the air out (expiration) inside is our pushed chests out by when we greater the compress than higher affecting our breathing rescue breathing into (artificial our factors (inspiration) resuscitation). chests. atmospheric pressure pressure. Inspiration During inspiration backbone, t he par t of made t he lower tough muscles ribs and brous of t he t he diaphragm sternum tissue. The t hat contract external connect and atten intercostal to t he t he muscles central contract 103 835292 CSEC HSB Unit B Topic 2.indd 103 08/01/2015 16:05 The breathing The mechanism and t he internal outwards. These decreasing is greater air ways During ● t he t han air pressure t he inating muscles air t he relax. increase inside pressure t he of The t he ribcage volume lungs. inside Now lungs, moves inside t he so exchange) t he upwards chest moves into and (t horax), atmospheric air system pressure t he lungs. external muscles contract intercostal muscles to move contract passage passage t he (gas inspiration: diaphragm ● intercostal movements respiratory of t he to diaphragm move t he down ribcage up and out. air air trachea trachea external external intercostal intercostal muscles muscles relax contract ribs move and out up ribs move and in down lungs lungs ribcage ribcage diaphragm the volume the chest the volume the chest of of cavity cavity diaphragm decreases increases contracts and diaphragm relaxes and diaphragm moves upwards down front front p view Figure during rib cage up chest side B.2.2.1(a) breathing Movement of the of rib cage and down moves diaphragm diaphragm thorax volume increases and down of side view of chest the ribcage p Figure B.2.2.1(b) breathing Movement of the diaphragm and the ribcage out Expiration moves up of thorax t he expiration abdomen shape. t he diaphragm pushes t he muscles central The internal intercostal intercostal muscles relax relax brous muscles and tissue contract t he pressure upwards and t he into a exer ted dome external decreases These volume chest inwards by of of chest During volume view during out moves view in moves and diaphragm of bulges lungs volume increases of lungs movements pressure inside so t he ribcage moves downwards decrease t he volume inside t he t he lungs. The elastic tissue t horax, around t he and inwards. increasing alveoli recoils t he air and decreases t his helps to force air out of t he lungs. Note that the diaphragm muscles and intercostal muscles are used together air pressure in lungs air decreases pressure in lungs when you breathe in and out. Sometimes when breathing with shallow breaths increases you can just use your diaphragm and the intercostal muscles are not used at all. The air flows into the breathing p Figure lungs air IN flows out of breathing B.2.2.2 Flow charts the breathing Tr y OUT happens breathing during breathing out is summarised in the ow charts in Figure B.2.2.2. this yourself showing Making what mechanism lungs in a model of the breathing mechanism and Requirements ● 2 balloons ● a clear ● a pair 1 Cut the plastic of off for a one-lung water model bottle (without cap) ● a thumbtack ● sticky tape or masking tape scissors the balloon part is of the going to balloon be the with the hole diaphragm in for blowing your into. The rest of model. 104 835292 CSEC HSB Unit B Topic 2.indd 104 08/01/2015 16:05 The respiratory 2 Use of 3 the the the in exchange) thumbtack water Cover stays (gas to system make a The small hole about 3 mm wide in the breathing mechanism bottom bottle. bottom place of you the can water fix it bottle with with the balloon. T o make sure it tape. balloon 4 Put the around the of second the top. the rim Y ou balloon of can the use inside bottle more the so bottle. the sticky Fold balloon tape to the hangs hold top of into the the the balloon bottle balloon onto from the rim bottle. plastic 5 Now use your model to show what happens to the lungs during drinks breathing bottle in 6 and breathing Match a the Which out. structures parts between are the of your respiratory represented bottle and the by: the system bottle, balloon, the to the the parts balloon, of the the model. space balloon diaphragm? cut b Which c What in 7 Use T ake some we Y ou can is respiratory with your system model as a are not way of represented in demonstrating the to teach the make bottle and a artist two-lung tubing. be to to The secured someone show draw by model an air how for plastic else in a tubing tight your much us with in better Figure Y - or a must seal. family your how we model breathing p Figure brain of exercise detects concentrations brain each changes of t he time integrates determines inuences ● A one-lung model to breathe is than the B.2.2.3. T -shaped t inside Modelling connector the clay opening could be and of the used on in blood breathing t he and oxygen t he and extent carbon to which t he Study ✔ dioxide you breat he in and out. The lungs breat hing t he our in an an increase increase increase t he information and rate of from inside breat hing. and outside Exercise is one t he body factor effects in in in of exercise breat hing t he dept h t he on breat hing and t hat minute information make happens a table to breathing in this in the showing following and chapter what during breathing ● diaphragm ● intercostal ● ribcage ● volume of thorax ● volume of lungs ● air ● movement out: muscles are: rate of the t he breat hing. shor t-term an all dept h tip are centre to ● we breathe. Use stretched ● B.2.2.3 how this. Effects The top model? show photographs asked plastic The the wrong model some for of humans? the one parts with off breat hing volume (volume of air breat hed in during pressure in the lungs a of air in the airways minute) ● an increase Regular exercise physiology. ● ● ● in t he also These has increase an expansion of an increase size in of carbon long-term dioxide benecial in expired effects on air. t he body’s include: an diaphragm in amount t he number t he of capillaries in t he lungs alveoli and strengt h of t he intercostal muscles and muscles. 105 835292 CSEC HSB Unit B Topic 2.indd 105 08/01/2015 16:05 The breathing The mechanism Other factors that affect respiratory (gas exchange) system breathing Drugs Some dr ugs, breat hing. e.g. amphetamines, Ot hers are are depressants stimulants and have and t he speed opposite up t he rate of effect. Anxiety If we are frightened increase our needs be to adrenaline removed. and t his Environmental You may and t here have is worried as about more This is because increases somet hing, oxygen t he is needed when rate of t hen and anxious t his is more we likely carbon tend to to dioxide secrete more respiration. factors noticed little increase in brain increase to or breat hing if you are ventilation t hat you carbon t hat dioxide t he in a small star t concentrations breat hing rate and room wit h yawning. in also t he to air. ot her t he people This is effect This stimulates of an t he yawn. Altitude As you move up concentration g round t his, about t he level our limit is at 2250 is and metres for difculties mountain t here dept h 5500 a remains less rate to above air but oxygen pressure as in 50% live. sea less People when t he t he breat hing is breat hing metres t he 21%, of t here humans in at decreases. air air is muc h breat hed increases. oxygen At t han used to living to cities in. ver y at travelling The In at at to altitudes level. sea t han response high sea like oxygen t hinner This level is of about exper ience Mexico City, whic h level. Weight Excess weight because it is can cause difcult for people t he to become diaphragm to breat hless. move This down is mainly properly. Sleep This at will reduce t he breat hing Fresh This air as ver y rate as t he little carbon dioxide is produced will environment reduce t he breat hing Effective rescue Sometimes person gas a exchange brain, which efcient ‘t he in is by kiss rescue person. had To sensitive an to lack accident of to oxygen wit hin called will breat hing. organs for a level be low. resuscitation) stops damage begin (once dioxide (articial prevent must breat hing breat hing This breat hing t hemselves perform has carbon its few – own This slows especially t he respiration minutes. mout h-to-mout h This – can be resuscitation life’). injured for who exchange rescue of breathing lungs. ver y During Rescue t he gaseous achieved or rate rest. rescue should again air is moved substitutes or be into t he continued until breat hing for aid from successfully and out of t he person’s own until person a t he breat hing you should lungs of breat hing begins machine follow is t he t he movements. to breat he available. steps To below. 106 835292 CSEC HSB Unit B Topic 2.indd 106 08/01/2015 16:05 The respiratory (gas exchange) 1 Lift the Pinch the hand, lower This the the the The nostrils shut with the fingers breathing mechanism of chin one Tilt system will air then jaw tilt the forward force the head so back the tongue chin and juts forward push out. and open passages. head backward 2 Take your a deep mouth against the breath, and seal person’s then your open lips mouth. 3 Breathe out firmly but Lift the person’s your mouth to look into the at off, then person’s turn your chest. If head you so have successful you will see that it has risen lungs. and 4 is now Repeat The Figure B.2.2.4 Step 1: Lie t he Step 2: Place Rescue injured one gently steps t he 2 as air and colour comes 3 at a should breathing out steady of start lungs. rate. improve should the up and again. breathing person hand tilt falling person’s eventually p the and been so mouth gently as into on on top head of t heir t he back. head, backwards to two open ngers t he air under t he chin and passageway. Step 3: Push the chin up to lift the tongue and search for and remove any debris (including false teeth) in the mouth. Step 4: Pinch t he nostrils of t he injured person, take a deep breat h, seal t he p Figure chest mout h wit h your twice. lips and breat he out B.2.2.5 is rising Checking and falling to see during if the rescue deeply. breathing Step 5: Repeat Step 6: Check t hat indicates Step 7: Check etc. for for for Step 8: signs When of t he position of of If yes, a rate circulation person (see injured breat hs circulation, circulation (at t he rescue seconds. of compressions for chest t he signs ten signs t he t hat is Figure of e.g. give ever y 10 per is rising effective colour, breat hs minute. 100 ever y person are If and per minute give to This B.2.2.5). swallowing, and cycles two falling. Figure movement, no, minute) (see of check 15 breat hs chest and check minute. breat hing normally, put t hem into t he recover y p B.2.2.6). Figure put NB It is essential t hat an ambulance and medical help are B.2.2.6 into the The person recovery should position be when called. they are breathing normally 107 835292 CSEC HSB Unit B Topic 2.indd 107 08/01/2015 16:05 The Smoking respiratory (gas exchange) system Questions 1 The diaphragm During the forced 2 a By the end should ● be outcomes of this able outline why topic you to: is so the the 5500 metres. 3 State 4 How five of volume b you other Smoking Cigarette smoke ● nicotine the the why than the used for muscles also diaphragm. thorax? b of breathing altitude, the that biological As at difficult result, affect principle an at breathing. contract, a pressure oxygen is gentle in the will lungs? altitude that pushing what of altitude. breathing. of rescue breathing to a volunteers? B.2.3 has of are abdominal concentration explain aid muscles against Explain factors, first the up percentage would constituents smoking a organs State group Learning to: intercostal expiration, abdominal happen and over 4000 substances in it. The impor tant are: – t he dr ug in tobacco t hat is absorbed into t he blood addictive ● ● explain the damage carbon monoxide – a gas produced when substances do not burn that efciently smoking ● explain causes the monoxide to effect on the the of lungs ● carbon tar ● ● black the effects on carcinogens Tobacco health against smoking present graphs data and on smoking a charts. dr ug t hat settles cancer-causing nicotine acts as a effect. difcult to in t he bronchi and bronchioles chemicals. it has and blood The carbon into B.2.3.1 The adverse effects on health people are widely people smoke is a choose feel that personal to the right dr ug to taken increase is a on into wit h is t hat t he one dr ug of t he healt h of as are people most defence dried and interferes say t hat t hat addictive dr ugs body also has of ten we is wit h t he it people cardiovascular t hen Nicotine t hroughout Smokers one a inhale. t hat cells and t he makes leaves body ner ve awareness. powerful t he plant tobacco vapour interacts Nicotine effects blood to t he in by carbon by up tobacco have to isolated it smoke haemoglobin. monoxide. 10%. circulator y air ways t he bronchi. a nd know system (hear t This also is reduces leads to t he volume because t he hear t of oxygen haemoglobin oxygen disease t hat and binds can damaged system. many settles It reduces This on compounds t he from epit helium at tar. t he When base of it is t he breat hed trachea Tar eventually destroys t he cilia t hat line much of our and gas known exchange still t he t he When of in smoking t he This up. in substance monoxide t he in present a which vessels). transpor ted Chemists is serious in ar teries is nicotine, herbivores. Nicotine give and permanently Figure it by stimulant calming be contain because carried Many liquid eaten physiology. and but – leaves being smoked, as our p oily oxygen outline of a transport ● of – system (see page 97). Cilia protect our lungs by carr ying mucus, smoke. decision to wit h it is trapped t he site and bacteria, from t he air passages into t he t hroat, where swallowed. Smokers of dust go on lungs. for secreting Mucus bacteria. epit helial cells The leads lots collects of in mucus t he destr uction to t he but have bronchi of cilia formation of and lost t he cilia becomes and t he scar tissue a continual (see to move good irritation Figure it out breeding of t he B.2.3.2). 108 835292 CSEC HSB Unit B Topic 2.indd 108 08/01/2015 16:05 The respiratory (gas exchange) system a Smoking b ciliated cilia cells mucus move along dust these cells particles make mucus ✔ Study There is about drugs use tip much nicotine more information in Unit You as an D.7. example can of a stimulant. p Figure B.2.3.2 airways, Many and smokers developing Wit hout become alveoli. lining the of The t he weakens the reducing walls the of condition they cannot is carcinogens to of tobacco Here t hey interact repaired t hen DNA changes If t he genes t he star t may to break if t his It took are cells one is It t hat not It or greater alveoli The to and blood bronchi The risk that they in t he of lungs can enter t he bacteria cells white reach leaves t hrough blood them. break people remove t he cells down cells digest Eventually enter t he DNA gasping carbon bronchitis wit h and and a p this burst, and for dioxide breath B.2.3.3 cancer begins form small a how lung cell divides tumour like this to (x50) efciently. of epit helial damage The it. If cells t his permanent lining damage change is in may take causes air ways and spread t hese out of 20 mutations control years symptoms it and into may g row blood ot her before (see are and a t hat for m t his B.2.3.4 a large Worse, a par t Cancers are control a of has B.2.3.5). area far cell tumour size and occupy vessels. organs. to tumour Figures to t hose star t of t he t he If lung tumour harder to treat scientists lung to a sur pr isingly cancer. r ise, e.g. Indeed, in t he UK long when in t he time t he to realise number 1930s and of t hat cases 1940s, cigarette of lung cigarette smoking cancer smoking Figure B.2.3.4 cancer ends area at the from a even suspected pollution a or t he team of as a cause! tar mac medical t hat It was was put scientists t hought on led t he by t hat ot her roads, Richard factors, might Doll be such – This the top heavy of is how cancer this smoker lung is lung after the white removed death. The was whole Then, is one happens. causes not This – as p began Figure emphysema. nuclei permanently. by divide discovered block off affected can B.2.3.3). into tumour and t hat t hen Figure grown a t he phlegm. mutation. division, (see and dust white much smoke bronchi. a t he of alveoli both not is cilia, bacteria. oxygen have which wit h exchange. t he DNA and emphysema. enough in obstr ucted coughing send so the diseases. the gas in smoke condition Par ticles t hese for smokers in is alveoli area called absorb long-term mucus lining the surface This of a and heavy damaged. destroy the who ot her response to through are and protection alveoli epithelium people inamed bronchitis body’s ciliated in bronchitis, pneumonia t he replaces bronchi, become permanently pathway Many tissue in develop bronchioles consequences The Scar especially as lung is full of deposits of tar air responsible. showed t hat t here Key terms ! was a statistical cancer. was a He high link studied between many correlation cigarette tens of between smoking t housands t he people of and t he people who incidence and found developed lung of t hat lung t here cancer and Emphysema Disease in break which large smoking. This convinced most people of t he work was not experimental. Instead, it ‘holes’ involved using data about of lung cancer in non-smokers as a sor t of control to baseline for comparison wit h t he decreasing the to lung leave surface for gaseous frequency in smokers. The exchange. Any change in the DNA establish in a the t he Mutation frequency of down link. area Doll’s alveoli graph a cell. in 109 835292 CSEC HSB Unit B Topic 2.indd 109 08/01/2015 16:05 The Smoking Figure B.2.3.6 1910 to from lung cancer In a t he t heir had of of an B.2.3.5 area that to the should This right be CAT of black scan the to indicate He for and UK. t he dogs t he cancer. c hanges. lung number t he Oscar signs developed lung t he over forced carcinogens shows backbone Dr in of This from to cancer the has same enlarged grown level in with this in the the cancer were out found t hat not exper imental tobacco smoke if New smoke occur forced work in men of each deat hs and t he in to later of system year men t he in did work link conducted cause had t he not on lung examined t hat people later conr med can dogs smoke and York, smoking t hat smoked early stages develop isolating between t he smoking cancer. are a number of social factor s t hat on which contr ibute is patient lung to cancer an increased caused unemployment, 30000 especially rep 4000 20000 fo nosrep 2000 deaths per year rep rebmun 10000 lung cancer for 1000 bot h class lower to who ver y women group, sexes. like people get t han years would recnac from t he r isk of smoking. pover ty, among men 15–25 morf smoked More raey hcae setteragic of cigarettes 3000 by developing These and include culture socioeconomic g roups. gnul raey dekoms shtaed 5000 number by number researc her nd cigarette He c hanges t hat smoked t he exchange) air. lungs heart a to inhale cancer. cigarettes shows (gas period. dogs There A of also same on same Dogs It Auerbac h, exper iments lungs t hese Figure 1980 1960s, ser ies cancer. p shows from respiratory Most give irritated infringements on On do by t he people up. smoke smoke, where what t heir who t he not except in numbers smoke ot her want t hey to personal as age similar say hand, give see t he are t hey many up and increasing liber ty as smoking 0 is 1910 1920 1930 1940 1950 1960 1970 banned in more and more public places. 1980 year p Figure cause B.2.3.6 of lung Evidence for the idea that smoking is the cancer Maths Study ✔ Presenting Statistics in on different Incidence disease ways. is the are Three of number a disease that occur data these of time period, during e.g. are: Smoking is responsible month or per activity per a is the disease in charts number a of same Mortality that proportion of early deaths. is about and presenting use the data. program to Y ou can present enter the the data data or you into a can draw and graphs by hand. Data on tobacco and its impact on your health from every country in the world. T able B.2.3.1 shows selected is data 13 countries including some from the Caribbean as published in the 2012 at of the T obacco Atlas. The table shows: time. is occur period, high people population edition the very year. for with a week, collected Prevalence for a own per smoking cases spreadsheet specic on expressed This of skills tip the number over e.g. per a of deaths particular week, time month or ● the number ● the percentage year . of cigarettes smoked per of the adult male adult female person population per who year smoke (prevalence of smoking) ● the percentage of the ● the percentage of deaths as a population result of who smoking in smoke males and females 110 835292 CSEC HSB Unit B Topic 2.indd 110 08/01/2015 16:05 The q respiratory T able (gas exchange) system Smoking B.2.3.1 Country Cigarettes Male Female Male Female per person prevalence/% prevalence/% deaths/% deaths/% per year Barbados 344 15 2 4 0 Bulgaria 2822 50 28 22 5 Canada 809 23 16 23 20 Cuba 1261 31 16 21 18 Czech 2125 43 30 26 10 339 12 3 9 13 Republic Dominica p Figure taking Guyana 49 29 3 3 283 23 8 12 6 1841 38 11 22 12 539 46 2 22 15 1106 30 21 10 1 Jamaica Japan B.2.3.7 risks This with 9-year-old his boy is health 1 Did you know? ? Malaysia In Trinidad and 2014, was T obago of UK 750 22 21 22 1028 31 23 US$23.6 23 who the Present the countries lowest data from on cigarette T able cigarette B.2.3.1, consumption including the as a bar chart by with the countries to Is there any of deaths against 3 Is correlation linked any to to of deaths correlation 4 Discuss 5 Suggest what between smoking, Case between smoking? smoking? the damages widow in 1996 of of a lung choosing highest six and Her informing of lawyers company was people consuming argued that negligent of the in dangers tobacco. consumption. percentage there linked company pay the died [Information 2 to 23 cancer. 1 tobacco 20 man USA a ordered other Plot in the data the data from disease in of to find death the of to percentage consumption find out. smoking and July 2014. from BBC News 20th http://www.bbc.co.uk/ news/world-us-canada-28389273 deaths out. in countries early and cigarette females presented these and and prevalence scattergraphs of consumption scattergraphs males between Plot limitations cigarette the table. would much make the link clearer. study Evidence for the link between smoking and lung cancer 53 100 a page what famous 109). might doctors habits British it. In Toget her he and to take par t in obtained of disease. information 1951, his t he in patterns epidemiologist collected cause was of he began researchers study. 1951 a and who on worked lung recr uited inter vals in cancer long-term Information at Professor nd of 34 439 about Richard Oxford to study t heir t hereaf ter Sir out British male British smoking until t he study egatnecrep doctors. He study lavivrus (see was t he 80 morf Doll is ega Epidemiology 60 cigarette smokers 40 20 0 was ended in 2001. When each doctor died, t he researchers recorded 40 50 60 70 80 90 100 age / years t he cause smokers of deat h. were The cancer, most common respirator y causes diseases and of deat h hear t among t he disease. p Figure B.2.3.8 doctors Figure B.2.3.8 shows t he sur vival of smokers and non-smokers doctors who were 50 or younger when t he study The survival between of 1900 male and among 1930 t he bor n – some of the results from the star ted. British Doctors Study 111 835292 CSEC HSB Unit B Topic 2.indd 111 08/01/2015 16:05 Cell The respiration respiratory (gas exchange) system Questions Talk about ? 1 Ban Why smoking! Consider the of following: 2 do t his you t hink long-term Professor Doll chose male doctors as t he subjects study? Use the information in Figure B.2.3.8 to state the percentage of male British doctors who had died by the age of 70 in each of the two groups. Over ● die 90% from the lung smoked ● of people cancer who have 3 Describe cigarettes. Up to 50% die early of t he smokers trends shown in t he results of t his study numbers of cases as shown in lung cancer graph. may 4 from t he In many in females par ts of t he world t he of smoking-related has risen shar ply in recent years. Suggest why t his has diseases. happened. Smokers ● die in are more middle age likely than to non- 5 Suggest smokers. T obacco ● than 5 use causes million The deaths by per a is the costs smoking time complete smoking your to tobacco. of ill are 1 Name and on two this 2 State the end 3 Suggest of this able explain define topic ● other than lung cancer, which are associated with pieces of evidence that link smoking to lung cancer. some and people have lower vital capacities than predicted by height. Cell the respiration role of heat. is the Energy breakdown was dened of food to on page 20 release as the energy ability in to t he do form work. of ATP Examples ATP cells in our bodies doing work are muscle cells contracting, ner ve cells respiration distinguish and t he you between anaerobic the oxygen debt describe white blood cells engulng bacteria, pancreas enzymes and all cells t his work taking up ions by active cells transpor t. respiration The explain impulses, aerobic making ● diseases, why age transmitting ● reduce to: of ● to Caribbean. outcomes and ● attempt t he smoking. two Respiration be can in with B.2.4 should cancer teachers. their By lung health huge. ban Discuss family Learning governments of introduce worldwide friends, which cases year cigarette Now in new Questions economic caused of more worldwide. ● ways number concept energy adenosine industrial to do comes from a chemical present in all cells, of to and domestic applications anaerobic respiration. lose a triphosphate phosphate (ATP). group and This releases form its adenosine energy when it breaks down diphosphate: of adenosine adenosine triphosphate (ATP) diphosphate (ADP) + phosphate (P ) + energy i All cells stay Key in all Cell Aerobic respiration chemical breakdown (carbohydrate, oxygen form and of of protein to ATP nutrients and release and cells – it breakdown ● fat) using of out form of t heir ATP in various t heir cells functions. if t hey ATP is are t he to continue ‘energy to of nutrients to ATP release and t he is t he in which process by all energy which t his transactions ATP is made. are currency’ It conducted. involves t he: energy stored in of t heir nutrients (mainly glucose and lipid) to release t he energy molecules in use of some of t his energy to rebuild ATP from ADP and phosphate: heat. respiration oxygen form carr y breakdown + phosphate energy (p ) + energy from nutrients ATP i without heat diphosphate The ● loss of t he rest of t he energy as heat. in There the supply is respiration adenosine Anaerobic using a The ● the alive have terms ! using must are two types of respiration: aerobic respiration and anaerobic without respiration oxygen. 112 835292 CSEC HSB Unit B Topic 2.indd 112 08/01/2015 16:05 The respiratory Aerobic (gas exchange) system Cell respiration respiration ADP Energy + In t his process t he breakdown of nutrients (glucose and lipids) Pi involves for cell e.g. t he use of oxygen. Carbon dioxide and water are always produced as activities, movement, waste making products and energy to rebuild ATP is released. The most commonly active substrate, Aerobic and t he only respiration of one t hat glucose cells can in be our brains represented can by use, t he is protein, used transport glucose. word equation: ATP glucose + oxygen carbon dioxide + water + energy energy Aerobic respiration occurs inside t he mitochondria of our cells (see used B.2.4.2 by a and B.2.4.3) molecule of and releases glucose in a great aerobic deal of respiration energy. is The enough energy to released rebuild up Pi 30 molecules of ATP from ADP and to during cells. ATP Cristae is and sausage-shaped infoldings of Figure B.2.4.1 recycles organelles t he inner found in membrane t he of cytoplasm t his organelle for respiration t hat cells do not receive enough oxygen for all t he t hey want to do. For tunately, t his does not the back respiration chemical slows down or stops. Cells can still carr y out many cell’s to provide activities reactions of respiration but t hey are unable mitochondria absence t his of because oxygen process cannot respire anaerobic respire bacteria Instead of is t he fat of t he breakdown by oxygen. when carbon to of make many and respiration, e.g. in is as waste a or This does form of not only lesser use to of ot her bacteria use acid is also write about fungi and in plants, respiration in occurs in cells make process sure to the role of you ATP . t he involve glucose. extent; oxygen. All some anaerobic We organisms can microorganisms respiration in yeasts and waste in products animals are produced (including in humans), lactic acid + energy known as Figure B.2.4.2 micrograph lactate.) et hanol and carbon dioxide are produced as added products: are glucose respiration energy-consuming of An a mitochondrion. waste remind energy. t heir p lactic to and product: glucose t hat A.2 cells products. water, lactic produced glucose respiration, anaerobic acid oxygen. greater We making dioxide a of Unit respiration. anaerobic respiration wit h lack anaerobic to of refer In continually A TP tip about you any that ● into mean or (Note all Pi aerobic When and Respiration and Exam yourself never ADP where Look our use and and respiration Sometimes In ADP made. Anaerobic t he released of ✔ t hat is from respiration energy are ATP P i Mitochondria glucose make to p about from Figures et hanol + carbon dioxide + to not this red electron section Colour image and – blue through has a been mitochondria (x 20 000) energy cristae The waste substances substances. molecules. from t he aerobic lactic Anaerobic Only two anaerobic acid respiration molecules respiration respiration. and When is of of et hanol wasteful ATP are glucose. sprinters r un are of t he made That t he still energy wit h is 100 energy-rich 15 t he times metres in glucose energy less t heir released t han hear t in and matrix lungs cannot respiration get so enough t hey have oxygen to use to t heir anaerobic muscles to maintain respiration instead. aerobic This uses lots inner of glucose molecules to generate t he ATP t hat t hey need. Their training outer designed to have energy lots make sure t hat stored as by t he time glycogen t he star ter because so gun much goes of t he t heir t he lactic acid t hey membrane muscles energy is wasted p in membrane is Figure B.2.4.3 Compare the structure produce. of the with mitochondrion this in Figure B.2.4.2 diagram 113 835292 CSEC HSB Unit B Topic 2.indd 113 08/01/2015 16:05 Cell The respiration q Study ✔ T able B.2.4.1 Comparison of aerobic and respiratory anaerobic respiration your is an opportunity maths skills. actual size Figure B.2.4.2? of the to What in system animals the Is mitochondrion respiration Aerobic Anaerobic oxygen required? Yes No A A in per much energy molecule What are of the is released lot Does it end occur little glucose? products? CO and H 2 you of practise is How Did exchange) tip T ype Here (gas in mitochondria? O Lactic acid 2 Yes No know? ? Mitochondria lead a semi- Oxygen independent They the take rest A TP in in of life from cell return. your and Y ou from your fertilised in to the egg become Humans back dur ing your mother are cells as Exam key produced much cell glucose energy than enough a that shor t of waste here is t here is oxygen, an oxygen you start respire builds oxygen we die. However, to active muscle anaerobically. Lactic acid up delivered muscle fatigue in t he and because soon muscle soreness. oxygen t he Lactic diffuses acid to t he lactic cells t hat is Dur ing are t his is going to be time needed to hear t acid. out and of t he muscle l i ve r. cells Hear t i n to t he muscle per acid a e ro b i c a l ly. gl u c o s e fo r sto ra g e molecule p rov i d e t h e m s e lve s end of all respiration. of t he e xe rc i s e lactic Fi g u re blood uses and is ox yg e n car r ied to of and the difference debt. exercise build up as we cannot get into our bodies. decit cells glyc o g e n c o nve r t and some re s p i re t he of t he re st lactic re s p i re acid a e ro b i c a l ly i n to to we to acid wit h e n e r g y. re s p i re has lactic been The acid e x t ra is re m ove d , ox yg e n called t he t he ox yg e n t hat t he is needed ox yg e n debt has debt. been at t he Once re p a i d B.2.4.4). ideal know as L i ve r deficit and a – real difference oxygen between an update oxygen negyxO the an to decit metabolise tip decit At and be ekatpu sure some product leading oxygen oxygen between t hat wit hout cannot that releases aerobic Exam Make so oxygen was (see ✔ aerobically: you. respiration less as respire exercise, tip message anaerobic to descended lactic The have vigorous quic kly away ✔ debt cells. from give inherited mitochondria those your compounds the mitochondria all inside that debt is lactic – needed extra to oxygen convert acid resting oxygen enough result oxygen we have anaerobic debt is lots of lactic respiration. the volume of The acid As a uptake from oxygen oxygen that before needs to respire be the ‘repaid’ lactic after exercise to Study tip Figure carefully at the graph. The is much the the curve oxygen that shows how was taken make up by Oxygen uses much We processes, also athlete. after exercise use uptake of of into the body anaerobic t he products of before, during and after strenuous exercise respiration anaerobic respiration in yeast and red bacteria. line B.2.4.4 Economic We Look exercise Time acid. p ✔ during exercise in Yeast t hese only providing is a and respire Usually for t he microorganisms making ser vices single-celled aerobically cells use not such fungus glucose yeast as initial page When anaerobically has many such breaking (see anaerobically. in substances access to to 9) down t hat t here for m industrial as is a beer our can oxygen so domestic yoghur t, but wastes. respire lac k et hanol and and of and t hat bot h oxygen, it carbon respires yeast dioxide. aerobically, 114 835292 CSEC HSB Unit B Topic 2.indd 114 08/01/2015 16:05 The respiratory produces t hen t hat and a lot of decreases is exchange) ATP and required. it For and system t herefore st ar ts divides respir ing centur ies Cell rapidly. anaerobically humans have The to oxygen produce exploited yeast in respiration supply t he product brewing breadmaking. Many bacter ia decreases of (gas milk . t he It pH might organisms do refr igeration most also of t he seem not and common respire wit hout sur roundings strange g row oxygen well, freezing, met hods if make at all, sour ing of and to food to has milk in and produce acid been go preser vation. used sour, pH. salting In lactic but t he foods Think in t he food days were of acid. This sour ing spoilage before two of yoghur t t he and p salted cod Figure B.2.4.5 These sprinters rely sh. on anaerobic respiration in their leg muscles Today fermentation is used domestic consumption. yeast bacteria and Domestic Many uses foods of and of make home beer, Tr y this Industrial mass t he home are also produce to produce industries a range large and of foods small for t hat use foods. fermentation beverages respiration (see to in There yeasts and wine yourself on be made in bacteria, can some examples making, pages bread t he making home using are and t he home yoghur t anaerobic brewing to making 1 16–17). uses of fermentation production of beer Brewing p The in Guyana brewing into is is t hen respires t he This Hot and t he t he is spent group is widely Red to in Stripe t he in germinated used added glucose t he B is and grain water yeast process, especially Barbados grain. maltose. cooled of and occurs to to it. Yeast form yeast extract be Jamaica. so t he and breaks et hanol can Caribbean, seeds dissolve down and eaten, The it is a Banks raw material breakdown t he to dioxide. rich Beer for and t his glucose and At source Figure B2.4.6 These runners (5000 aerobic respiration long metres) in distance depend their leg on muscles starch maltose maltose carbon as e.g. t he end of vitamins, Gentle warming vitamins. Breadmaking Dough will is produced allow t he dioxide. The causes to it et hanol yeast by to carbon rise. dioxide When t he our, down causes dough water, t he is sugar sugar, t he dough baked, and yeast. producing t he to et hanol increase yeast cells in die and volume and carbon t hat t he evaporates. Practical Rising mixing break Activity dough p Figure B.2.4.7 Mauby, which is made Requirements from ● stirring ● measuring jug ● measuring cylinder, ● thermometer, ● timer ● laboratory fermented bark rod 3 e.g. e.g. 50 cm 0–100°C balance 115 835292 CSEC HSB Unit B Topic 2.indd 115 08/01/2015 16:05 Cell The respiration ● water ● plain ● dried baths set at a variety of respiratory temperatures, (gas exchange) including system 40°C flour yeast made into a yeast suspension (add 7 g jug suitable dried yeast to 3 450 warm water and stir) sugar ● 1 cm Add 25 add 1 Add 30 g g of of flour to a measuring or other to the container and then until you sugar. 3 2 cm have made Pour the of a the yeast smooth suspension paste that can be flour and sugar. Stir poured. 3 3 to p Figure for B.2.4.8 industrial Fermenting alcohol sugar paste into let the paste Note the volume a 50 touch cm the measuring sides – this cylinder is very and take great care not important. cane production 4 water 2 baths. minutes of for about 5 Repeat steps 6 Record your 7 Plot a Y ou can plot the axes. This way of more easily use the the for to than plotting b Explain c Suggest should the the of if Suggest the Place and note the cylinder the volume in of one of paste the every temperature each time. table. the for they a cylinder. different volume the are on the the separate allows graphs. and Alternatively, dough increases temperatures results spreadsheet graph. of different presenting on print use you It is them the on to the graph for time. same compare quicker, out with pair them however, everyone drawing to to facility of program. effect effect suitable be a a how results the spreadsheet Describe in show in temperature minutes. using results a d 1– 4 the 30 results graph collect paste Record of of different temperatures temperature controls for this on the on rising the of investigation dough. dough. and explain why they included. ways to improve the investigation. Yoghurt Bacteria, They t he such ferment protein, yoghur t is Making Lactobacillus lactose lowers not avourings Tr y as t he to and this t he and sugar pH and ever yone’s in Streptococcus milk gives taste so to t he give are used lactic yoghur t a sour manufacturers to acid, add make which taste. such yoghur t. coagulates Natural t hings as fr uit. yourself yoghurt Requirements p Figure B.2.4.9 Homemade yoghurt ● any ● spoon type ● stirring ● measuring ● sterilised ● pot of of milk rod jug container, live yoghurt glass (check jar or the plastic label to cup make sure it contains live bacteria) 116 835292 CSEC HSB Unit B Topic 2.indd 116 08/01/2015 16:05 The respiratory ● a ● foil 1 Heat (gas exchange) system Cell respiration thermometer or cling wrap some milk in a saucepan to about 75°C. Allow to cool to room temperature. 3 2 Pour 50 cm into a sterilised container. 3 3 Add 1 cm 4 Cover the 5 Place to 6 6 If the hours you a do and try in a not of the with different live ingredients things to add a What b Research of is it doesn’t is the if different yoghurts almost to as hygiene of it hourly and fruit, intervals. keep this of the precautions in milk, a school even at In order 42– 43°C for of you milk adding the nuts, milk. eat the and coconut live yoghurt; the bacteria; seeds, may lab. goat’s before source – thoroughly. 37.7°C. powder the at try appearance make types yoghurts Try adding oatmeal. The range endless. nutritional online the milk but wrap. below you gently observe drop in stir should suitable product your and you changes with and cling place skimmed to milk or bacteria, any some the foil warm kitchen eat adding using a ensure record Do different of in to with cultivate experimenting milk; try milk this product. yoghurt container properly Keep Try live value find out of yoghurt? what food additives are in different brands yoghurt. c What are d Design these an additives investigation for? to find the best temperature to use for of star ter making yoghurt. Case study Acidophilus The yoghurts production cultures of two of all yoghur ts star ts wit h bacteria: Lactobacillus a to t he addition bulgar icus and ✔ Study tip Streptococcus Microorganisms thermophilus. If food is be marketed as a ‘yoghur t’ t hen it has services be made using t hese two bacteria t hat can sur vive in milk, respire for (milk sugar) and make lactic commonly acidophilus added to is anot her yoghur ts. species This is of bacter ium because it has t hat unique is are benecial to human to sur vive stomach acid healt h. before not conditions of climate. gut it has This infections. promote a many healt h benets ‘good of bacter ial in t he break Firstly, it is highly enter ing our resilient intestines to t he gut har mful known as a wall and down ‘pro-biotic ’ which is promote for its why it the in human aerobic anaerobic biogas page 118). generators Make a list of all the and of microorganisms and add to and, microorganisms environment, often an t hat you work through the book. acidic cause ability is as to now yoghur t. brands can diarrhoea is bind of Lactobacillus bacteria’ This to deter t herefore leading and wellbeing. is found Today, gassiness It ability helps positive commonly t hese an acid many sewage proper ties it secondly, works although conditions uses able in also (see t hat provide Bacteria acid. wastes, Lactobacillus us. t he treatment lactose also to help and because yoghur t to so are acidophilus. alleviate bacteria to an based brands symptoms contribute t hese marketed Leading such increased increase in on t he claim as sense number t hat bloating, in of t he 117 835292 CSEC HSB Unit B Topic 2.indd 117 08/01/2015 16:05 Cell The respiration large intestine, digestion. intestine people is t he Some of t he yeast for Danone which t heir uses t hey Yoghur t a per and ar ticial of of to have to yoghur t a have diseases. of Some adver tisements also claimed t hat claims t hey are not effect. t he large When consequence intestine. drinks as have developed extravagant healt h company Bidobacter ium of between However, sucrose, and had improving antibiotics. Spanish–French ‘bad probiotic have t hereby system lactis, ActiRegularis®. contain yeasts exchange) repopulate made population probiotic which t hese as a drinks sweeteners, Manufacturers bacterial have (gas unwanted large known Bidus of an have Bidobacter ium, as use t he t he and also yoghur t and example, trademarked pot t he in and bacteria can diseases, bacteria For bacteria’ and bacterial yoghur ts products. strain ‘bad yoghur ts infections for probiotic have needs million yogur ts of t he t hese benecial manufacturers strains out in antibiotics deat h claims or crowding bacteria following take special 20 The respiratory to suppor ted fr uit by and of sugars bacteria’ yoghur ts be 10 many feed on. prevent wit hdrawn scientic t hese (fr uctose) childhood from evidence. Question How would benets of you design probiotic a long-term study to investigate t he healt h yoghur ts? tap Biogas to production house Some types met hane of bacteria (CH ) as t he sur vive waste entirely product in of anaerobic t heir conditions respiration. and Met hane release is a gas 4 methane + CO 2 water seal t hat is a way to useful source of energy; it is one of t he gases in natural to mix gas. One inlet tank dispose bacteria Figure ground pump and of human, collect B.2.4.10 is a t he animal gas diagram and plant wastes is it wit h t hese produced. of a small scale biogas generator. Many of t hese digested are level used across t he world, especially in remote places where t here is no sludge mains (used drainage and unreliable or non-existent supplies of power. They are as fertilizer) also used to supplement national power supplies, e.g. China where t here partition are millions of t hem. The met hane is used for cooking and heating and (retains may coarse also be used to generate electricity. sludge) Questions sludge p Figure B.2.4.10 generator wastes and cooking used to uses A turns and domestic animal it into heating generate and biogas methane and 1 a What does ATP stand 2 Describe the role 3 What the waste for? b Where is most ATP produced in the cell? human can gas also be of ATP in a human cell. for electricity are respiration 4 What 5 Explain as 6 are in the why products human waste long muscle a aerobic respiration, b anaerobic respiration in yeast run during tissue? products distance of of anaerobic runners cannot as fast cells? their event sprinters. List the products that are made by bacteria and yeasts for human consumption. 118 835292 CSEC HSB Unit B Topic 2.indd 118 08/01/2015 16:05 The respiratory (gas exchange) system Cell respiration Summary The ● ● ● respiratory Breathing is refreshes the and carbon The airways – upper – lower The many The in of the and so have – are a the Expiration the rate dioxide ● ● Vital in ● of much Respiration ATP is the in to into into air the blood and larynx cartilage, ciliated and and which alveoli. prevents epithelium protects exchange that alveoli the includes from dust. surface. carbon gases two: bronchioles viruses give to the in Gaseous dioxide diffuse that across occurs the cell linings of of oxygen and carbon big space for steep diffusion to occur concentration gradients to the in relax the in part and thorax the the (chest) contract and carbon that Air pull there moves down intercostal is a down the muscles ribcage. of muscles the the the ribcage the brain. increases, altitude and relax and diaphragm atmosphere by so to external decreases, blood drugs, oxygen atmosphere. and diaphragm central than thorax the muscles raise of alveoli. than controlled of a diaphragm the the some diffusion concentrations enlarging the is for maintain the lungs the total series from falls air under air is during mass contents the the in force the forced increases e.g. body the into pressure and It up if of lungs out. the carbon exercise. all influence the dioxide mitochondria efficient in air is movement breathed fully reactions energy that cilia, occurs and currency cells, out after breathing inflated. glucose respiration inside of is are mainly the from occur that lungs chemical energy that requires and where that of the to all such synthesis of as of the the inside cells to fat. cells. It is energy- active proteins transport and membranes. respiration carbon of triphosphate) membranes, Aerobic so macronutrients, processes of volume possible transferring manufacture are with distance Diaphragm of of the as (adenosine consuming ● is air energy involved across Inspired breathing. release ● lungs. diffuses dioxide by higher anxiety, by and The the blood muscles breathing capacity as is throat epithelium oxygen that the concentration Smoking, rate it lined blood when volume so of so push The open This area contract Intercostal is short and carbon happens gravity. divided bronchi, gaseous of with dome ribs held of out. are bacteria, maintained thorax. The a air inside abdomen increases ● is gradient. fibrous tract out continually surfaces: achieved pressure between of is diffuses blood. surface are and capillaries. and pressure central ● the well-ventilated Inspiration as body’s between monoxide the the is cells. diffusion into oxygen nose/mouth, tract such the there oxygen are air so trachea, tract The well-supplied for lower tract: tract: and large of lungs continually exchange thin – air system respiratory air, the the dioxide ● the form is alveoli are – dioxide respiratory alveoli Gaseous – the mucus-secreting between ● in respiratory exchange the movement air collapsing. particles ● the exchange) respiratory lower airways (gas it oxygen. water. most releases of Many the the The of ATP energy products the is to of reactions produced. make aerobic occur Aerobic about 30 in respiration the respiration molecules of is ATP . 119 835292 CSEC HSB Unit B Topic 2.indd 119 08/01/2015 16:05 Cell The respiration ● Anaerobic do not respiration use of cells respire can to carbon made The not first the falling ● ● in drug calming When scar T ar beating; also not the ● are Carbon of having ● away making ● a Bacteria up the gives the and is of they require breaking acid each muscle but down (lactate). two molecules is making sure that the stage breathing is the of ATP checking lungs. airways gently to see These but if the stages are firmly chest should is be unaided. is a most off stimulant addictive tar and It the yet carbon claim it has monoxide. damages airways smokers drugs. mucus-secreting blocks exercise, that lactic Cells for only airways. the ATP system the cells and in cilia to so that secrete response they more to damage carcinogens cells and cells and are to leading form many to tumours vessels through takes cancer-causing airways blood spread cancer that the grow blocking combines can be bread lactic used of that to for or the and body years to chemicals. mutation. which airways. to Cell These division can spread The cancer cells form secondary cancers develop sufficiently before the is birth the is is women who are to to human, sewage reduce This an made milk to blood. exploited Y oghurt causes in in pregnant breakdown and haemoglobin giving yeasts making. acid generators so birth respiration with transported especially premature are lining symptoms. that and make biogas Lung but Anaerobic to in monoxide smokers, it of stimulates lungs any oxygen of available. produced – into It of Instead product involves third gone is exchange) respired. breathes one burnt, fills controlled elsewhere. the oxygen ATP strenuous lots efficient (gas forms. DNA break there it is stage no During end less nicotine. lining contains through can is is the is less glucose. glucose has person It the which damage is effect. tissue air from breathing mouth; the tobacco of there much producing much second that and respired. water is rescue tobacco damages mucus, and the person’s until T ar of showing The stop ● stage is energy molecule repeated a ● per when rapidly, the respiration obstructed; into that very all dioxide Anaerobic are glucose getting occurs mitochondria molecule without ● their respiratory at underweight commercially by go the bacteria sour plant and and volume serious all risk of baby. in brewing, that form animal for greater respire wine lactose yoghurt. wastes in works. 120 835292 CSEC HSB Unit B Topic 2.indd 120 08/01/2015 16:05 The respiratory (gas exchange) system Practice 8 Practice Section 1 Which carcinogenic substance is found in Questions cigarettes? Questions A nicotine B tar C carbon D sulphur A Which of t he following statements best describes vital monoxide dioxide capacity? 9 A The maximum volume of air taken in During inspiration, air travels t hrough t he lar ynx and during into which of t he following? inhalation B C The maximum The maximum af ter D The a deep capacity volume of of air air in t he t hat can be move volume of air taken in t he diffusion B active C osmosis trachea D bronchiole during 10 exchange, A D 3 gas from bronchus C breat h minimum During oesophagus B exhaled inhalation 2 A lungs by alveoli which to t he process does Which of oxygen Which Carbon blood? dioxide A of t he following is not needed for respiration B carbon glucose D enzymes Which of t he following 1 Ribs 2 Volume 3 Diaphragm 4 External raised A 1,2,4 B 1,3 4 16 0.04 21 D 4 16 a Differentiate describes b Identify c Fill inspiration? in the t he flowing of t horax Air decreases. site intercostal t he muscles following enters relax. The air t hrough t he respirator y t he respirator y moves into t hen a is not a characteristics of t he air splits sacs is blood in humans. passage tract. [1] about air [5] tract into t hrough called into The two air t hrough t he t he nasal lar ynx t he cavity. (voice t he smaller t hen tubes passes called t hrough called even which called at t heir have ends. Carl was in a car accident and had stopped area An emergency responder t he scene, administered ar tificial who was first resuscitation to supply revive Carl. lining dioxide due to being t he B almost C lower D greater diffuses t he from carbon t he dioxide ________________ same blood into t he concentration t hat in t he alveoli. in t he ii) alveoli. four Identify t hat as t he List major resuscitation. t he will ar tificial same as steps in administering component help ar tificial [4] t he victim resuscitation impor tance. of t he who and exhaled is state air receiving its [2] t han 2 a i) Name do t he par t of t he respirator y tract where t han gas humans following ventilation A What exchange gas i) blood ows tube branches help Carbon exchange t he t hen and on Thin gaseous for breat hing. Rich gaseous surface? surface Good of and d Low terms blanks contracts. smaller of t he [3] upwards. 2,3,4 This between breat hing. 3,4 Which 79 B . exchange 7 79 79 small 6 (%) 21 79 which D Nitrogen (%) B box) C air? dioxide C B expired C and A about Oxygen (%) 0.04 Section 1 5 tr ue to place? oxygen D is transpor t A C following breat hing take 4 t he t he reactions of anaerobic respiration in ii) produce? A carbon dioxide B carbon dioxide C lactic D et hanol List exchange t hree surface iii) and lactic acid State [1] characteristics found t he listed occurs. in impor tance above in a of humans. ii) of t he gas exchange [3] each characteristic [3] acid and carbon dioxide 121 835292 CSEC HSB Unit B Topic 2.indd 121 08/01/2015 16:05 Practice b The Questions The diagram exchange in below shows t he site of gas 4 Anaerobic respiration microscopic humans. a Define respiratory occurs (gas bot h in exchange) humans system and in organisms. anaerobic respiration. [2] air b i) Write a word respiration Low in to humans. show anaerobic [2] concentration ii) Explain t he humans. c High equation i) Write impor tance of t his reaction in [3] an equation to show anaerobic concentration respiration in yeast. [2] X ii) Red blood 5 X and ii) Draw arrows direction move. iii) State in Charlene now. t he What ii) 3 One has State is i) State in on move during process? t he Gas X gas [1] diagram to and show Gas Y name of in exchange. gas she Gas smoking was one sign of t he and Define Explain a Y t hat The Two of of term a What for wit h five are of t he Number of smoked per two types vital you below capacity would [3] effects on t he healt h and [2] expect cigarettes t he for 10 vital capacity years to var y of from [3] shows smoking t he relationships lung cigarettes day between cancer. Annual death cancer per rate 100 from 000 0 10 1-14 78 is the t his [2] ability to lung men 15-24 127 ≤25 250 respire. characteristic occur in Constr uct bar above. graph of t he data in t he [3] [1] following of table respiration which Describe in 1 t he trend seen in t he graph. [2] compares humans. Explain Respiration how smoking cigarettes can lead to [6] d Respiration Give t he cancer. names of [3] two ot her diseases t hat smoking 2 can mitochondria a humans. lung Factors severe State bronchitis. iii) t he have [3] respiration. [1] respiration t hey? Complete anaerobic t he humans. years ii) i) to organisms. non-smoker. table b by explain reaction [2] disease. things impor tance types can smoking cigarette are example, t his during energy how table i) ii) t he person t hat will of smoking b t he released of [2] t his living Gas cigarettes diagnosed of organisms. X named body. a c bronchitis? characteristic a will which been Recently, i) Y what [2] involved c Gas by t he is uses Cigarette of exchange Energy t hree X Gas a impor tance d i) Using cells lead to ot her t han cancer. [2] of Location Cytoplasm of cells cells 6 ______________, Sue an Reactants is par ticipating hour before in a t he race for t he school she sprint drinks a event. spor ts About drink half to glucose provide ______________. a Carbon energy Suggest t he main respiration nutrient in t hat her t he muscles spor ts drink dioxide, ______________, supplies ______________, and explain t he advantage of taking such a Products drink ______________. before t he race. [4] ______________. b Number of Explain during molecules t he Sue race can and develop how she an oxygen will be debt able to repay per about molecule how ATP 30 2 t his debt. [5] of c glucose At home, Amanda ii) For Respiration above, explain identified produced iii) Describe as in 1 described what carbon cells. t he role in happens dioxide t he to table t he when it product Sue is and her fascinated sister how the bread word equation, how sister with was Amanda the bread made. bread is share and Explain, made a sandwich. asked using using her the yeast. [6] is [3] of ATP in t he cell. [3] 122 835292 CSEC HSB Unit B Topic 2.indd 122 08/01/2015 16:05 Unit B The B.3 B.3.1 The role of circulatory blood system Learning By Why have a circulatory the organisms do not need a circulator y system. The t he surface of a single-celled organism to t he centre be is ver y oxygen can reach all of t he mitochondria in t he cell by diffusion dioxide can pass out in you explain why t he same way. Also t here is enough humans need a system and ● carbon topic to: small circulatory so this able distance ● between of system? should Single-celled end outcomes state the composition of surface blood membrane in contact wit h t he surroundings to obtain enough oxygen and ● to lose all t he carbon dioxide produced in list the substances respiration. transported Many-celled distances animals between have surface much and efcient enough to deliver increase t he of diffusion rate more centre oxygen to bulk are all t hrough t han much t he an single-cell greater cells of organism and t he organisms. diffusion body. decreases As is The ● describe many-celled surface exposed demonstrate area and t he comes and excreting in ot her The an area surface by most animals such as Figure by blood cells blood cells ratio It they is do and several three but wit h sizes ammonia is calculated t he shows exchanging as relatively ratio t hat oxygen steeply. and little wit h an red ● describe the process of clotting. body exercise between and of white distances ver y mat hematical Calculating different for bodies simple and will surface increase carbon in dioxide urea. ratio volume shows of t his. A blood 1 cylinders system, of such volume. imagining B.3.1.2 circulatory wastes because compact surface volume to its spheres, principle less skills and area organism have surroundings. animals relatively Maths Surface t heir impor tance volume size animals to the roles not blood Most in the of animal quite not difcult have cubes. A regular three we the the surface surface dimensional can area area of of shapes, demonstrate the ‘animals’. ‘animals’, does dividing measure However, cube-shaped these by to A, B and C. Animal C has a not. p Figure B.3.1.1 medical from Phlebotomists specialists people for who take laboratory are blood analysis A B C 1 mm 3 mm 5 p Figure 1 Calculate Figure 2 B.3.1.2 the Three cube-shaped surface area and area to ‘animals’ the of mm increasing volumes of each size of the ‘animals’ in B.3.1.2. Calculate the surface volume ratio for each ‘animal’. 123 835292 CSEC HSB Unit B Topic 3.indd 123 08/01/2015 16:07 The role of The blood 3 Explain Copy your q why T able ‘animal’ B.3.1.1 C (or has a type circulatory into a system, spreadsheet) but and circulatory ‘animal’ add the A system does results not. of calculations. T able B.3.1.1 3 Cube of Surface Volume / mm Surface area: 2 side / mm area / mm volume ratio 1 2 24 8 3.0:1 96 64 1.5:1 216 216 1.0:1 3 4 5 6 4 Use ratio the 5 Describe 6 Explain 7 Using the Humans will we ✔ tip not do skin circulatory system is as system. the It is comprising organ system the heart, blood red of t he The not and platelets confuse (gaseous it white and with t hese and much so wit h circulator y most surface to to volume t he why from distances obtain carr y of humans. the surface area: 1:1. diffusion animals, system area axis). area explain that as surface graph. graph, to of horizontal the simple surface graph your less adequately body As on a the measure table is cells cells enough a to your of curve on we t he are enough have a body too substances large. oxygen special to surface area and Also even if for from our gas all t he blood – the circulator y a tissue t hat system is consists composed of of: cells suspended in a liquid which is blood plasma. the exchange) comprising in humans draw body. human mostly cells, and the difficult trillions have of to volume cardiovascular an ● vessels, of table (put also cells known is permeable. exchange The it figures supply was your shape ratio have not in volume the why volume Exam results against Do respiratory ● system trachea, water lungs and blood vessels – smallest of between blood tubes t hese t hat tubes and carr y are t he ‘leaky’ respiring blood to to allow all par ts exchange of of t he body. The substances tissues diaphragm. ● t he hear t – a muscular Functions of The of functions amino of heat acids, blood blood include oxygen, against reproduction, page the t hroughout defence organ carbon t he disease e.g. t he body t hat t he for is blood transpor t dioxide t hrough penis pumps and of around substances, antibodies, t he temperature regulation t he white made action erect of by t he t he use e.g. glucose, distr ibution (see blood of body. page cells blood 197), and (see 244). 124 835292 CSEC HSB Unit B Topic 3.indd 124 08/01/2015 16:07 The circulatory Blood The system The role of blood structure composition of human blood is represented as a char t in Figure B.3.1.3. blood plasma water 55% blood 90% dissolved erythrocytes substances 10%, e.g. amino (red blood cells 45% leucocytes cells) (white blood thrombocytes cells) (platelets) glucose, acids, hormones, antibodies, proteins salts, (fibrinogen, prothrombin) p Figure Role B.3.1.3 of Plasma is Composition of t he liquid par t of t he in Table B.3.1.2 information in ot her Units. T able transported in dioxide hydrogen blood. which Its also functions shows you in transpor t where to are nd more B.3.1.2 Substances Carbon blood plasma summarised q the plasma – as Site of into the absorption respiring carbonate Site of delivery Unit plasma and page number tissues lungs Unit B2 pages 98–101 other Unit B1 pages 80–81 all Unit B5 ions Nutrients small intestine liver and all organs Water small and large kidney intestine Hormones ductless Urea and other pages 179–183 organs (endocrine) specic target glands for each liver kidneys organs Units hormone B6 and 219–224 Unit B5 B7 and pages 252–254 pages 175 and 187 and 179–183 Heat muscles and liver skin, over Alt hough made are blood from described Red Red numerous or our numbers ever y are out. worn as a cells uid, have notice t hat impor tant, all Unit almost but B5 pages 197–202 half specic, of it (45%) functions is which cells cells, of These and body below. blood blood behaves cells. lungs the er yt hrocytes blood day In a to cells. They replace healt hy as t he t hey are also made cells human are t hat each in are drop known, bone are marrow destroyed of t he blood most in huge because contains t hey about 3 5 million so red numerous widest blood blood cells. This t hat t hey clumped if is equivalent toget her to 1 mm t hey of blood. would block They all but are t he p vessels. Figure B.3.1.4 micrograph Red blood cells do not contain nuclei or any organelles such t hat t here are Instead over 250 t he cytoplasm million is full of haemoglobin haemoglobin. molecules in In this blood electron you can see red as blood mitochondria. of It each is estimated red blood cells biconcave cells with disc (yellow) their characteristic shape, and white platelets blood (pink) 125 835292 CSEC HSB Unit B Topic 3.indd 125 08/01/2015 16:07 The role of The blood cell. our 8 Haemoglobin blood, Figure from B.3.1.6 our enzyme lungs t hat carbonate ratio can for shape. gaseous pack in Large surface exchange. more No membrane to through capillaries. allow area to nucleus haemoglobin. surface Elastic them is t he pigment to remove shows, to t he ions for t he cells catalyses plenty Our ● t he of ability to Anaemia 2 µm ● of some bones. Live be – transpor t t he most monoxide High carried liver and 17 spleen. weeks then Usually cells, and are destroyed between 4 to of our haemoglobin body. conversion in t he Red of is blood carbon plasma. to transpor t cells also dioxide This into enzyme oxygen contain an hydrogen dioxide as it ows t hrough helps respiring t he blood to tissues. oxygen 6 is common affected cause is by: a lack of iron in t he diet (see – this by altitudes – red gas This blood t here is binds permanently binding cells less reduces and oxygen causes in t he the to haemoglobin volume drowsiness air at high of forming oxygen and even altitudes, that death. but for people approximately t hese 64). Carbon can marrow role of transpor t carbon carboxyhaemoglobin. the makes cell squeeze page in which red. volume so ● Produced molecule system µm As Biconcave appear circulatory in living or travelling t here acclimatise by forming many more red the blood million cells. 3 per mm and blood. some Function carbon is to transport oxygen dioxide. q p Figure B.3.1.5 lungs (high Red oxygen blood T able B.3.1.3 Comparisons concentration) Feature White Nucleus Yes Mitochondria Yes Size / µm 8 Contains haemoglobin red haemoglobin oxygen (HbO to ). blood (Hb) form (Note white blood cells and red to blood cells blood Red cells blood cells No No 20 8 No Functions haemoglobin between cells Yes Defence against • phagocytosis • production Transports infections: carbon oxygen and dioxide in cell combines of antibodies with oxyhaemoglobin that one molecule White blood cells 8 of Hb can carry four oxygen molecules) White oxyhaemoglobin haemoglobin ‘picks up’ and and some takes it splits oxygen of the back up to blood the dioxide lungs There are and vacuoles. t hat (low oxgen several in B.3.1.6 transporting The also 1 mm made of in bone blood but mar row. t he There number are about var ies quite 10 a 00 0 lot. different types of white blood cell, including phagocytes cells, are from two bone pat hogens types of marrow and cell debris, phagocytes. to organs, and digest Monocytes such as t he are lungs t hem wit hin phagocytes and intestines, concentration) t hey spread Figure are in engulf There move where p cells lymphocytes. Phagocytes tissues cells 3 white haemoglobin carbon to blood give role oxygen of of remain providing pat hogens. an impor tant Neutrophils travel in line t he of defence blood as a against ‘rapid t he reaction haemoglobin force’; blood during an searching infection for Lymphocytes are concentrated in system and invading Lymph Figure are part on page protein pathogens. pathogens is spread lymph and widely nodes reproductive nodes process pat hogens pour out of t he destroying t hroughout in system organ which t hem t he systems are bone t he marrow by body, like most t he phagocytosis. but t he into t hey gut, likely tend to be respirator y to be infected by microorganisms. B.3.3.8 special t hey of the 1 42. molecules Antibodies together known as in lymphatic Many that kill of them protect microbes clumps system produce against directly making which them you antibodies bacteria, or help easier can see which vir uses and phagocytes to engulf. in by This are other ‘sticking’ clumping agglutination. 126 835292 CSEC HSB Unit B Topic 3.indd 126 08/01/2015 16:07 The circulatory system The Monocyte Neutrophil role of blood Lymphocyte nucleus partially permeable membrane 8–10 20 µm 12 µm µm vesicles containing enzymes p Figure B.3.1.7 The different types of white blood cell bacteria phagocyte foreign p ‘recognises’ the it bacteria Figure B.3.1.8 Tr y Looking this at phlebotomist A technician in collected a slides, Figures 1 Look 2 Use the 4 Use the you draw. Label their at drawings and blood from laboratory B, and added B.3.1.9 and B.3.1.10 Figures in B.3.1.9 Figure of each magnifications them using a a person smeared blue are stain two who the to was in good blood across make the photographs health. two white that blood he took and B.3.1.7 p Figure B.3.1.9 Blood p Figure B.3.1.10 smear A (x300) B.3.1.10. to identify the cells that you can see cells that in your drawings cell type given with the to from the calculate names of photographs. the the diameters cells and of add the notes about appearance. Suggest relative of A drawings Make 6 digests enzymes photographs. 3 5 it microscope carefully the some haematology cells light ‘flowing’ cells microscope a by yourself blood visible. them them Phagocytosis A through ingests around how you numbers would of red use photographs blood cells and like white these blood to calculate cells in a the sample blood. Platelets Key Blood smear B (x400) term ! Platelets marrow. are In a tiny non-nucleated healt hy human, cell t here fragments are formed approximately in t he 250 bone 000 in Platelets Small that have fragments of cells ever y do not nuclei; these cell 3 mm of blood. They are involved in blood clotting, a vital process which fragments prevents entr y of excessive blood pat hogens loss t hrough from damaged damaged blood vessels and prevents t he start the release blood substances clotting to process. skin. 127 835292 CSEC HSB Unit B Topic 3.indd 127 08/01/2015 16:07 The role of The blood Figure Key is terms B.3.1.12 formed shows when a t he mesh major of stages protein in bres t he clotting traps red circulatory process. blood cells The to system clot make itself an ! impenetrable Prothrombin dissolved changes in An the into inactive plasma thrombin enzyme blood vessels barrier release when wounding chemicals t hat occurs. star t t his The platelets and damaged process. which during Calcium ions platelets to have several roles in blood clotting including stimulating blood release substances t hat activate an enzyme in t he plasma. This clotting. Thrombin The plasma converts that enzyme in enzyme conver ts anot her enzyme thrombin. plasma protein, prothrombin, into t he active blood brinogen The nal step in t he cascade is conversion by t hrombin to of t he plasma protein brinogen into brin t hat forms a mesh to trap brin. blood Fibrinogen protein that A globular changes blood from A brous brinogen clotting to prevents T able protein during form a blood Red blood mesh of Exam entr y of pat hogens. Summary table of the functions of blood cells cell Functions cell 1 Transports oxygen 2 Transports some from lungs carbon to dioxide tissues from blood (cell is cell fragment) prepared such out Protection system use if you between and to lungs if as phagocytosis 2 producing Protection from blood brinogen. someone is by: 1 It by antibodies releasing plasma is decient used in factors by in to activate removing diagnostic the t he blood blood tests, such clotting process clotting as t he test to iron. is a have cells, good acts to on tissues, blood organs tissues tip circulatory distinguish B.3.1.4 blood White loss. nd to and that protein example loss formed Ser um The blood brin Platelet ✔ stop clots. T ype Fibrin and plasma into q when cells organ systems. Think platelets release protein the prothrombin of a list blood heart starting cells and and with red ending blood and with white enzyme thrombokinase the vessels. thrombin acts on blood calcium protein ions fibrinogen and vitamin also K needed fibrin p Figure fibrin strands cells. These a scab B.3.1.12 The at trap dry the red out wound stages in blood and form site blood clotting 128 835292 CSEC HSB Unit B Topic 3.indd 128 08/01/2015 16:07 The circulatory Case system Declan’s Declan is about t hat will of he but is right not small to need operation t he type. This blood antibodies not t his, blood A, B and D. have There require operation. of blood medical Declan’s and during t he a is blood are of will Before of blood group always A+, take impregnated blood type cer tain supply nurse t hat major wrong he a are operation. order t hinks cards two doctors t he to because using t he him His have mot her it identify give staff matter test are t he cell surface cell discovered ABO is present and if D simply Test is groups. blood and If t hey t hat a wit h did could on t heir cell ot her more minor B, present of t he of and O. blood t hen In ABO is are blood g roup (so four Rhesus Rhesus in blood is Rhesus system; types (or not A because t here positive do people. g roup called system known which most blood system There t he group t he t he membrane molecules transfusion Rhesus monkeys). AB t he blood molecules Rhesus A, in surface in are just D it two. positive) negative (or negative). cards drop drop surface t hen not also molecule in system: D molecules are consideration B t he A serious doesn’t t hat may t he was If cells and usually is of of like t he water blood is is one in added added Figure to to B.3.1.13 each each test test are area area used to and to test activate mixed Declan’s t he wit h blood. antibodies. t he liquid. A The Anti-A rst t hree t hat in t he t he areas test detect card four t h is A, B and working D. The properly. four t h The area blood is a control should not to AB+. If they shows t he results for Declan’s positive test with negative all three with all test of areas, them - Nome blood. the the person’s blood When work out carr ying that out there are operations eight t hat different type blood is O−. group If staff stocks are almost low it always may be uses may blood blood require possible to of use t he types blood a same You can - Focha example blood of type O− can be given to all as blood ot her de ABO Rhosus so does it has not none of stimulate t he t he t hree cell patient surface to t he - Fecha Signature - 2003-09-04 Firma SA Figure B.3.1.13 The adding Declan’s blood A, antibodies results after patient. to the card group, blood molecules, produce Anti- Data Pos. find out B his blood group. Was his groups mother because Nacimianto altogether. to for Dirección transfusions, type different - is p hospital Adrress BMJ A probably control coagulate Born tests Anti-D/Anti-Rho area. B.3.1.13 blood Anti-B check Name Figure If blood fatal. Red as t hey a begin, special be of group transfusions cer tain. of blood have can blood sample do role study Find ing t he The or D correct? and t hat will type O− control anti-A anti-B anti-D Person agglutinate in t he emergencies blood if t here Immediately before t he blood patient’s and an is block no blood time to operation, wit h t he a blood vessels. nd out nurse Blood t he patient’s repeats supplied by of t he t he test blood blood to is used type. cross W match bank. X Figure B.3.1.14 (W, Y X, and shows Z). results Identify t he of testing blood blood groups of from t he four four people people tested. Y Sometimes t he t he t hemselves. patient blood t hat is This used in transfusions happens in has been donated cases of rare blood groups surface of t he blood cells by wit h Z uncommon if t he types patient diseases. In is of molecules worried most cases, about on t he t hough, t he risks blood of infection comes from wit h a and blood-borne blood bank and is p Figure tests B.3.1.14 of four Results of blood people 129 835292 CSEC HSB Unit B Topic 3.indd 129 08/01/2015 16:07 The role of The blood normally as HIV People and to q t heir Blood is kept future blood groups T able donated volunteer result rarest blood as blood to le so been t he r un blood t he donations. groups in donate on tested will staff Blood low. Jamaican for major vir uses, such of rst t he banks Table have t heir blood tested blood bank know how of ten B.3.1.5 nd shows t hat t he supplies of distribution of population. B.3.1.5 group Percentage the Source: has system hepatitis. who t his label t he safe and circulatory of Blood group Percentage population the A+ 23.0 A− 2.0 B+ 20.0 B− 1.0 AB+ 23.0 AB− 0.5 O+ 47.0 O− 3.5 Jamaican National Blood Transfusion Service: of population http://www.nbts.gov.jm/pages. php?id=6 1 Choose Table and draw B.3.1.5 to an effective teach a group way of to present younger t he information students about in blood groups. 2 Explain being 3 why it is admitted Explain why impor tant to hospital blood is cross to know for t he blood group of patients operations. matched immediately before an operation. In September repor ted getting 4 5 its t he stocks Jamaican of O+ National and AB− Blood blood Transfusion were low and A+ Ser vice was low. Suggest AB− t hat 2014, why t he Jamaican blood bank had low stocks of O+, A+ and blood. How would you encourage people to give blood? Questions 1 Why 2 State 3 Explain 4 Describe the role 5 Describe the process 6 Explain 7 State 8 How high 9 do single-celled three functions why the three does organisms oxygen role of ways the of of is body need a circulatory system? blood. not included in T able B.3.1.2. lymphocytes. of phagocytosis platelets in not which a in the red acclimatise using bullet points. blood. blood cell is to the low an example, adapted content of to its function. oxygen in the air at altitude? Using the between circulatory cells, system tissues, as organs and organ explain the relationship systems. 130 835292 CSEC HSB Unit B Topic 3.indd 130 08/01/2015 16:07 The circulatory B.3.2 system Heart Heart structure and function Learning By Structure of the the end hear t is a muscular organ t hat pumps blood t hrough blood t he body. Figure B.3.2.1 shows what t he human hear t be from t he muscle which looks of describe front. The tissue found here t hat makes up most of t he hear t is is shown and nowhere else in t he body. Cardiac in are relate Figure B.3.2.2. connected. Notice Cardiac t hat muscle t he bres bres are at t he bottom branched communicate wit h each ot her and contract like of right right coronary the explain blood explain the left atrium left coronary ventricle is (b) two blood from into ventricle A cardiac vein major blood cava drawing pumps t hat ventricles. There to is veins t he from Notice of lying so which whose the heart side by atrium and to t he of walls atrium resistance atria ows do into aorta and side an contraction ventricle Each no move, pulse. ventricle the vessels Figure (Figure B.3.2.3). Each side ventricle atrium t he to not t he are of walls t he each a at side as from into prevent t hick low blood as Blood blood t he an t he atrium ar ter y. (a) viewed The dark An external from red the view front structure at of of the right of the heart is the left the atrium ows Valves backow of hear tbeat. not blood ow have on during atria pumps atrium. forces B.3.2.1 heart receives top blood pressure artery body. between heart explain the a ‘lubb–dupp’ the artery B.3.2.1 hear t the of arch p The within functions atrium descending Figure their cava vena p structures to toget her. left right and heart so ● vena structure the t he t his ● aortic the of heart sound t hey you muscle ● photograph topic to: cardiac the tissue this like ● is outcomes able function viewed function vessels ● around and heart should The structure and t hick as t he pressure as t he t he walls into blood of t he t he ventricles. does not have far ventricles. Did you know? ? The walls of t he muscle to pumps blood of t he pump body. t herefore ventricles to t he t he The t he blood lungs lungs blood are are t hicker against and t he sof t, pressure in a because greater lef t have resistance. ventricle spongy t he t hey organs The pumps because pulmonar y ar ter y much right blood t hey does more to are not cardiac ventricle t he full rest of have air; to be Cardiac type of fatigue. of high as lungs do not give much resistance to t he ow of is a much circulation and lef t give a higher ventricle t han t he greater because has right t he resistance to organs are not t he blood. resistance to create a to high t he ow like pressure of t he To blood lungs; overcome and in t he t hey rest are t his t herefore of t he much denser resistance, has – – is the that other two smooth become only does not types and fatigued if blood. they There The muscle skeletal ver y muscle muscle a t hicker t he wall work muscle body is is like for in long. tubular the attached Unit too gut; to the Smooth organs skeletal in the muscle skeleton (see B.4). ventricle. 131 835292 CSEC HSB Unit B Topic 3.indd 131 08/01/2015 16:07 Heart structure and The function circulatory system T o get an idea of pressure and resistance, think about turning on a tap attached to a hose pipe. If you turn on the tap a little way, no water comes out of the other end of the hose pipe because the pressure is too low. Now gradually turn the tap further to give a higher pressure and you nd that water will overcome the resistance of the hose pipe and emerge from the far end. carotid superior vena artery cava pulmonary vein pulmonary aorta artery left right p Figure B.3.2.2 Cardiac from ventricle. muscle tissue atrium atrium a taken has with had fibres an This photograph electron colour (brown, added pink was microscope to and show and semilunar inferior vena muscle purple), a bicuspid tricuspid capillary fibres the (orange) that and transmit ventricles modified impulses (green) (mitral) though cords (x750). p (valve Figure = deoxygenated = oxygenated B.3.2.3 showing the blood blood Structure pathway ventricle of taken the by heart and associated blood vessels blood bicuspid B.3.2.4 Human heart tendons) ventricle left Figure valve valve muscle right p valve cava valve dissected semilunar to show the the heart Y ou can at left the see side top the with of very the the top thick wall of the tricuspid left its ventricle, tendons. B.3.2.3 and the bicuspid Compare valves of photograph. valve with valve and Figures B.3.2.5 X Y p Figure of the Figure B.3.2.5 B.3.2.5 viewed A drawing made of a cross section of the heart at the level valves from shows above. a section The across valves t he labelled hear t X and X is t he valve at t he base of t he aor ta where Y is t he valve at t he base of t he pulmonar y it to Y show t he four valves are t he semi-lunar joins t he lef t ar ter y where it valves. ventricle. joins t he right 132 835292 CSEC HSB Unit B Topic 3.indd 132 08/01/2015 16:07 The circulatory ventricle. t he When ar teries, you t he can system see t he blood in t he Heart pressure ows in back drawing t he ventricles towards so closing t he t he is less t han ventricles, valve lls t he t he preventing pressure t hat Study ✔ tip hear t. It The heart’s is and blue conventional The hear t people t here beats have is a at about hear t special rates tissue 72 beats higher Muscle in impulses regular inter vals. t he per and known pacemaker. t he minute, lower t han sino-atrial sino-atrial alt hough node t his. node In perfectly t he which contracts and right is t he emits healt hy atrium does hear t’s These impulses spread across t he not colour own electrical t he t he rest of t he cardiac muscle to contract, rst t he blue. can increase along speed also that blue to lungs. in and blue. blood red as Blood This changes it is Deoxygenated goes red, atria red and oxygenated blood blood is is and red. These colours are not ventricles. very brain the red hear t bright t hen show in blood mean from through dark stimulating blood deoxygenated never at to pacemaker oxygenated to function into Red We and in ‘pockets’ backow structure up speeds and ner ves t he up decrease t hat hear t t he end rate t he on and hear t t he to rate by sino-atrial slow it sending node. down. The impulses We send from out hormones t he to use that impulses different is blue the contain adrenaline people hear t. muscle closed bicuspid diagrams colour of with because veins deoxygenated decided that blood light-coloured in skin. semilunar closed tricuspid in someone sphincter semilunar valves so valves bicuspid and tricuspid valves open and valves closed open deoxygenated oxygenated a Diastole (between blood blood beats) b p Figure Blood The B.3.2.6 ow The through contraction state, when contractions t he of a the chamber cardiac of heart during systole one (atria heart contract) c Ventricular on each side of t he hear t is t he hear t not is called contracting, systole. is called The diastole. Study ✔ resting contract and relax at t he same time. The The same and relax time as involves and each t he (a): Diastole from t he venae (Figure Stage of (b): t hem stage, so and t he t hat systole two next a different complete time hear t from beat is t he atria called a but at cardiac section t he cycle the on blood ow much easier understand an heart is if you have or YouTube animation a access to to clip. stages. and ventricles pulmonar y t he tricuspid is – relax veins. pulmonar y bot h volume Blood muscles blood One and from t heir increases. bicuspid atria at tip and blood Semilunar ar ter y enters valves and aor ta into t he same time. t he hear t prevent t he any ventricles (a)). Atrial consequence, – cavae blood B.3.2.6 ot her. following Stage backow contract contract) two through ventricles (ventricles beat The atria systole heart of muscle the Atrial at will valves one higher into t he contract decrease slightly around forced atria t he so into t hat ventricles t he t he pressure pulmonar y way at veins blood ows B.3.2.6 venae a pressure t hrough (Figure and As wit hin t he (b)). cavae At t his constrict ventricles. 133 835292 CSEC HSB Unit B Topic 3.indd 133 08/01/2015 16:07 Heart structure and The function Stage (c): Ventricular contracted. decreases t he The so t hat ventricles valves are higher blood is t he t han t hat into in Use happens what you t han As t he t he – bot h relax. pressure shut. Written What now greater pushed ows systole atria in t he t hem t hat t he ventricles As in increases. t he pressure ar teries, t he pulmonar y contract ventricles atria, in t he and af ter contract, t he so t he valves aor ta t he bicuspid also are (Figure system atria t heir Eventually ventricles semilunar ar ter y circulatory have volume pressure and in tricuspid becomes pushed open and B.3.2.6(c)). Activity during have one just heart read and beat the diagrams of the heart to answer these questions. 1 What happens during to a ventricular 2 What are 3 What is 4 Suggest the the a roles role role photographs of of for and the volume systole the the the Explain why the left 6 Explain why the walls the bicuspid semilunar valve diagrams 5 and when the pressure in the ventricles contract? tricuspid valves? valves? the is the and tendons of ventricle of b ventricles that thicker atria you can see in the heart. are than much the right thinner ventricle. than those of the ventricles. 7 Using take 8 0 0.5 1.0 1.5 Figure in What B.3.2.3, getting type of from blood describe the right vessel is the pathway atrium a the to the aorta; that a red blood cell would aorta. b the vena cava? 2.0 time / s Figure B.3.2.7 is a timeline of changes that occur as the heart beats three times. diastole Use p Figure Figure B.3.2.7 to answer these questions. B.3.2.7 9 Calculate 10 List 11 At the 12 At q T able a what and b heart sequence what valves the stages open, in rate of stages in B.3.2.1 the cardiac The parts of the Function cavae these atrium ventricle Pulmonary arteries Pulmonary veins ventricle Aorta one heart cycle do the tricuspid and cycle do the semilunar beat. bicuspid valves a open, heart, blood its associated ows from the blood body to vessels the right and their atrium functions through deoxygenated blood from the body and pumps it into the ventricle Pumps deoxygenated Deoxygenated Oxygenated Receives left Left during veins Receives right atrium occurs close? Deoxygenated Left minute. close? Venae Right per that cardiac b Structure Right beats events the and in blood blood blood ows ows oxygenated into from from blood the the the pulmonary heart lungs from the to to the the artery lungs left pulmonary through atrium veins these through and arteries these pumps it veins into the ventricle Pumps oxygenated Oxygenated through this blood artery blood ows (the into from largest the the in aorta left the ventricle to the rest of the body body) 134 835292 CSEC HSB Unit B Topic 3.indd 134 08/01/2015 16:07 The circulatory Heart lungs Figure ● If are ‘lubb’ ● – ‘dupp’ listen search The as see listen of to t he body closure of bicuspid t he can borrow makes and a you t hat such as t he blood in ar teries from hear t be action pumped is t he pulmonar y of in normal be t he sounds hear t. valves (sof ter stet hoscope from (see These hear t and by par ticular (louder sound) hear t hem sounds t he for online. number of yourself If you different problems. t he aor ta are t he of and tissue. builds up t he blood t he high ar ter y ventricles and pressure system. The t hat enables contraction of t he pressure. pulmonar y As stretched a circulator y expand. remain contract, As t he relatively t he aor ta ventricles constant and relax, t hese p t he recoil As The its t he as person’s ar ter y. ow. The As a cuff cuff is to are a t he is This to is t he blood of blood gradually t he bit t he not an kilopascals t he SI for unit unit (kPa). so and a fall systolic blood vessel Figure B.3.2.8 stethoscope of along his to A doctor listen to uses the a heart beat patient in for example owing. t he brachial t he ow t he hears blood 80 and pressure. mmHg in sound diastole. (millimetres so resistance t he systole at blood of t his for to blood t hen, as two normal diastolic. we arm t he blood These The and t he in of ar ter y up in mercur y) book largely an goes ar ter y of t he pressure. depends blood diastolic pressure, in between t he rst and in stretches ow reducing t he band blood stop of The owing to ventricular mmHg for in impor tant blood friction blood keep nurse t he narrower, to pressure pressure mmHg use or during t he causes pressure deated pressure to ver y band. system, a is ventricle. resistance inated doctor more, systolic 120 is keep lef t becomes t he recoil elastic t hrough increases cuff an t he vessels ows vessel t he of and circulator y disease, The wit h blood pressure take profession pressure. mmHg a t his t he This pressure diastole blood happens pressure medical of result deates pressures blood If may corresponding t he model t hrough walls diameter. blood during B.3.2.9). t his t he can blood staff Figure original which diameter. Medical (see You recoils wit h narrowing t he t heir travels and ease to maintain and blood blood on to ar teries. systole function sound). hear t sur prised indicate hear t source elastic ar ter y t he around main contain helping and valves. tricuspid valves of may of sounds t he semilunar demonstrations sounds’ sounds, movement ‘lubb–dupp’ t he t he you hear t pressures vessels structure pressure to t hey if some ‘hear t ventricles The closure pumping blood t he of t he Blood and closure to to breat hing, by – for sounds used caused possible, or are during B.3.2.8) sounds Heart sounds Stet hoscopes t he system for will The blood conver t p Figure B.3.2.9 Measuring blood pressure 135 835292 CSEC HSB Unit B Topic 3.indd 135 08/01/2015 16:07 Heart structure and The function q T able the Part B.3.2.2 Shows circulatory of the blood pressures circulatory Maximum pressure atrium Left ventricle artery (in Figure cuff and to it records blood the is the B.3.2.10 blood flow patient’s displayed. data systolic to The and kPa), diastolic (12.7 kPa) beats per and phone person’s is the is Minimum pressure the leg) blood (kPa) 0 10.7 16.0 10.7 16.0 10.7 4.7 2.0 1.3 0.7 Vena cava vein 0.4 0 Right atrium 1.1 0 Right ventricle 3.3 0 rate data send mmHg heart Femoral of where can doctor. 147 pressure the heart transmits smartphone pressure pressure pressure, The the blood parts 16.0 Capillary p blood (kPa) 1.1 Aorta Femoral different system system. system Left in circulatory 95 rate His Pulmonary artery 3.3 1.1 Pulmonary vein 1.1 0.8 (19.6 mmHg is 77 minute Many doctor s blood pressure. pressure and and clinics Figure use a ppa ra tus Th e re t he to t he da t a allow are n ow t h ey shown ma ny co lle ct do c tor s to in Fig u re dig it al c an be mon itor B.3. 2. 9 meter s stored t h eir for and to me asur ing sen t patie n ts measure to b lood su rger ies remotely (se e B.3.2.10). Pulse The ar ter ies relax over feel is t he wr ist is we r m like The most carotid (where which saw cardiac or t he t he affect earlier, centre sends hear t pacemaker and alter by t he hear t adrenal where Several it factors yourself t he in increases affect per alter t he over hear t to required. rate. times of for t he t hick t he pass movement pulse wr ist when near t hat to muscle) rate. An be and bones). area stimulate t he Hormones, The stress. hear t pulse over recoil t hey to t he you felt on The skin can are t he in t he inside usual pulse rate pulse and This places and ar ter ies minute. impulses as contract where bone. passes pulse t he t he diet or felt passes beats the be common ar ter y 72 rate glands opposite), muscle ner ve t he ventr icles to ar ter y ner ves decrease t he swelling approximately Factors As when slight pulse. (where t he rate a somet hing neck of expand causing hormone It travels in t he brain pacemaker too, stimulate adrenaline in t he is called to t he increase t he produced bloodstream to t he rate. rate, stress, for example which of ten exercise leads to (see t he Tr y t his secretion of adrenaline. 136 835292 CSEC HSB Unit B Topic 3.indd 136 08/01/2015 16:07 The circulatory Tr y The system this effect of Heart structure and function yourself exercise on pulse rate Requirements ● Timer ● Graph A good and a electronic to how this your wrist your own 1 After determine long person Start is, as Wait rate monitor five by to return tness to heart nding your pulse in Figure sit count give seconds quietly your your and beat repeat for step ve in 1. a set to you their resting amount its counting for rate measure returns When pulse pulse to after and B.3.2.11. down is normal their then 2 to quicker minutes by someone’s takes shown pulse, 30 it the activity answer 2 heart paper way see tter or it. are of resting Place heart exercise. rate The value. two condent ngers about over taking minutes. 30 seconds beats per Repeat and multiply p the Figure The at wrist again and calculate the Y ou A to should good to to down 4 After 5 30 an or the seconds your Wait 30 your pulse flight 10 pulse for that of activity is to if you see are how in long good it your heart Repeat 8 Plot 9 a Find of step 6 graph raise five your times, heart rate, running such on the as out from 30 the task, seconds then, exercise for your heart your thumb for two Repeat this again, and heart rate graph your heart investigation good subjects. level of Y ou might activity neck. Do here not when taking the use pulse measure and your multiplying measure multiplying your by heart by heart rate by 2. rate by 1 40 counting 1 00 80 60 40 20 2. 0 rate against has returned to its resting return how to long normal it takes (see from Figure 1 2 with Make other sure people. first that it Friends is safe and for and like to their see if there recovery is a correlation 4 the to 5 6 7 8 9 10 Time/ min before during after task task task end B.3.2.12). family them 3 value. time. approximately rate to p Figure B.3.2.12 heart A rate graph showing might be what before a and members do between a period of exercise. Notice how the the exercise. the 120 after make on 160 person’s 10 or walking spot down. of seconds until of own either rate 0 7 felt health. takes ups. sit end for and 30 will stairs press the seconds this fitness exercise after your be exercise. activity doing doing counting after a with your nim rep staeb /etar t raeH on up can rest. continue Decide and at assess normal minutes 6 rate only way return 3 pulse T aking pulse your your mean B.3.2.11 pulse. minute. their heart case rate. rate about recover takes five after and the some time, a minutes, half exercise has in this to stopped Questions 1 What 2 Where 3 What 4 Which 5 What 6 Explain the 7 In terms is is the of the used heart’s blood part is are for a pacemaker? pressure? the contraction heart What How does produces b relaxation does it ‘120/80’ the highest of heart control (cardiac) the heart muscle? rate? mean? pressure? pulse? why the blood pressure does not decrease along the length of arteries. which part of the blood system does the greatest fall in pressure occur? 137 835292 CSEC HSB Unit B Topic 3.indd 137 08/01/2015 16:07 The circulatory Learning By the end The system B.3.3 outcomes of this topic The be able define the term circulatory all the structure of the circulatory hear t the to their have of a t he double body, a circulation red blood (Figure cell will B.3.3.1). pass This t hrough To understand t his, look at how many Figure B.3.3.1. Imagine a red in to t he lungs. return to its Look at original times it goes t hrough t he hear t position. veins and B.3.3.1 shows t he two circuits taken by t he blood: t he pulmonar y of systemic circulations. Pulmonar y circulation is t he circulation of blood capillaries from t he hear t to t he lungs and back. Systemic circulation is t he circulation functions of ● circuit system structure and arteries, humans each twice. cell order Figure relate for human in ● mammals, t hat and blood function system system t he describe circulatory double means ● system to: Like ● system you Double should circulatory circulatory describe the structure blood t he function of the from t he hear t to t he rest of t he body (not t he lungs) and back to and hear t. lymphatic system The advantages of a double ● describe how tissue fluid circulation are LUNGS and lymph are oxygenated formed. Low blood (red on diagrams) and O PULMONARY 2 High CO deoxygenated blood CIRCUIT 2 (blue) are kept separate and the left Key terms ventricle pumps blood at a much ! higher pressure into the systemic Double circulation Blood travels circulation than the right ventricle through the heart twice in one High pumps blood to the lungs. O 2 complete circulation of the body. Low CO 2 Oxygenated almost fully blood Blood saturated with that Figure B.3.3.2 shows a more is detailed version of the circulatory oxygen; SYSTEMIC it carries its maximum volume system. You will recognise some of of CIRCUIT oxygen and less carbon dioxide than the names of the blood vessels from BODY deoxygenated blood. Deoxygenated has about oxygen carbon it 70% can of the carry dioxide earlier Units and you will learn blood that p Figure B.3.3.1 u Figure B.3.3.2 human double Double about others in Units to come. circulation maximum and than Blood is The details of the HEAD more circulatory ARMS in pulmonary oxygenated & system artery pulmonary vein blood. superior vena LUNGS cava aorta Heart hepatic vein hepatic artery LIVER hepatic portal vein inferior STOMACH vena INTESTINES cava renal & vein renal artery KIDNEYS t Figure body. B.3.3.3 This The virtual computer LOWER generated image circulatory system upper of part the shows in the & BODY LEGS the body Deoxygenated blood Oxygenated blood 138 835292 CSEC HSB Unit B Topic 3.indd 138 08/01/2015 16:07 The circulatory system The circulatory system Artery This artery small ver y muscular wall wit h lumen many t he elastic ar ter y to bres allows wit hstand endothelium and maintain a high blood collagen pressure. fibres elastic and fibres smooth muscle ×10 Vein Veins have much t hinner vein walls elastic fibres t han pressure is t he much muscle lower. large as and blood smooth ar teries lumen collagen fibres They if blood increases during t he can easily exercise. semilunar expand volume as of happens Veins valves to have prevent endothelium backow. ×120 Capillary The lining of capillaries is capillary made from one layer of very thin endothelium thin cells. There are tiny holes (one cell thick) between the cells which make capillaries ‘leaky’. This is ideal for the exchange of substances (e.g. glucose) between the blood and tissue uid. As the cells are thin there is a very short distance for diffusion of oxygen and carbon dioxide. ×4000 p Figure B.3.3.4 The structure of arteries, veins and capillaries 139 835292 CSEC HSB Unit B Topic 3.indd 139 08/01/2015 16:07 The circulatory The system ● In Unit t he B.1 delivering ● In Unit circuit In B.2 Unit and q saw you B.5 to and t he t he one followed t he t he t hat system blood from t hrough ● you digestive hear t in pulmonar y you will hepatic liver. taking por tal Note it t hat vein t he circulatory transpor ts liver has blood two system from blood vessels away. t he pat hway of blood t hrough t he pulmonar y ar ter y to t he t he pulmonar y lungs and back vein. follow t he circulation from t he hear t to t he kidneys back. T able B.3.3.1 Summary table showing the differences between arteries, veins and capillaries Artery Thick, No Vein elastic wall valves Blood under Blood ows Normally high in pressure spurts carries oxygenated How Veins ● blood low ● A capillary elastic Very thick Valves No Blood under Blood ows low pressure smoothly carries deoxygenated is not Skeletal muscle t he from legs. Valves t he – vein As t hese back veins Par tial vacuum cavity decreases are t he in to to push in the the Blood under ows if we are contract hear t. The all blood standing by get or skeletal t hey and low cell way pressure carbon an artery to sitting dioxide here in back back muscle, squeeze one smoothly pressure the to i.e. exchanged Connects blood helping wall, valves Oxygen heart surrounded muscles t hey the back region to a vein the to the veins the hear t. upright. par ticularly t he veins, pushing t he muscle contain. t he B.3.3.5). to heart essential prevent (Figure the pressure head t hese blood to sufcient are t he – to blood thin Blood are Carries low following direction B.3.3.6 it heart at – t he Figure less tissue returns blood that The against p the Gravity in ● from blood carr y hear t. ● with blood Carries so wall Normally blood is Capillary Thinner backow As a result, of blood t he when blood must squeezes ow in one pressure in t he hear t. chest – during inspiration t he chest network atmospheric move along a) air t he muscle (see to page be 103). drawn major veins This into and relaxed par tial our into b) vacuum lungs, t he muscle but it not also only causes causes blood to hear t. contracted blood pushed vein through open valve valves closed valve prevents back flow p Figure B.3.3.5 The action of semilunar valves in veins 140 835292 CSEC HSB Unit B Topic 3.indd 140 08/01/2015 16:07 The circulatory Tissue If blood cells system never t he lef t t he can t hrough of back one walls to layer t he blood nutrients t hrough Refer of of ver y need. ar teries t he Figure vessels, t hey t hin B.3.3.4 t hin and walls to cells it would Oxygen veins of see substances capillaries Figure colon; Figure to a Note t hat, t here because be able to nutrients t hey are supply cannot too body leave t hick, but t hey t he pores lining of between t he capillar y t hem. This consists ● is a shows t he ● at are a body dense is a cells, of surrounded gaining far end of t he and t he blood pressure t he form capillar y t he of t he The small tissue network showing of into capillaries makes it easy t hat each Tissue t he cell epit helium in a tissue in is term ! leave uid under how molecules uid The surrounds the ltration blood uid cells. It is that formed by t he of plasma. ver y tissue the t he and ar teriole ions wit h and near a so from and to ions) fatty taken in t he much nutrients acids, end of t he t he blood and (e.g. t hey t he capillar y exchange passing out t he loss t he vessel pressure of inside t heir products wastes t he venule acids, by and venule, blood t he stay which ot her t he result, t hat leads proteins, nutrients between As uid and glucose, cells t hen molecules wall now tissue and vitamins is of less uid into waste (e.g. is from causes t han t he reabsorbed veins. products carbon metabolites, given dioxide, excess out by cells unwanted ions) the capillaries at end capillary the uid dioxide fall. t hat e.g. and capillar y to at molecules tissue oxygen amino leaves pressure molecules, by uid: capillar y oxygen fluid tissue small t he friction pressure of diffusion. cells blood carbon blood t he high large t he tissue by diagram forces lining hormones), t he t he formation which t he substances, (e.g. bat he relatively blood cells exchanged B.3.3.7 in t hrough red be capillar y. capillaries ● to and B.3.3.6 close ● system capillaries. t hat wit h not and Key for circulatory uid wit h pass The venule arteriole network some back tissue into fluid the passes capillaries arteriole the rest enters of the the tissue lymph fluid capillaries Key term ! Lymph system. into p Figure B.3.3.7 Formation of tissue fluid and The It uid drains lymph in the from lymphatic tissue uid vessels. lymph 141 835292 CSEC HSB Unit B Topic 3.indd 141 08/01/2015 16:07 The circulatory The system Lymphatic right into lymphatic the right duct empties subclavian left vein subclavian Not all of the lymph These veins uid by in ows in in small vessels by muscles nodes The lymphatic t he t he When a of of ten; to ensure The it body larger is uid the inside moved that slowly squeeze more energy a colourless many uid, white rich the blood in cells. contain valves; contraction of vessels are (see page t he blood have t he lymph is 339). Along lymph in in t he Figure blood lengt h, These groin, lymph veins are neck accumulate immune t hrough of t heir nodes. t he Eventually, system surrounding movement Lymphocytes impor tant (see t he legs). common armpits. and like t he of here response returns in t he to neck B.3.3.8). star ts the to exercise, muscles which is do their much provided by muscles more work. respiration. star t This The contracting means that respirator y harder they rate and need increases tip because need an organ we muscles more so far. It is (see other pages organs, 105 and such 1 12). as the The diaphragm breathing and rate hear t, and depth of both increase and the cardiac output of the hear t also increases to situated supply the ATP and have breathing mentioned of the these thin-walled valves and into of B.3.3.7 . exercise person more is (rat her veins region system Effects side like Some Figure intestine and the of in drain are direction. contains par ticularly to system. shown lymph Lymph and lymph not into blind-ended villi in is one is into vessels lacteals moved spleen are which movements Lymph of The lymph semi-lunar vessels lipids from Study reabsorbed duct lymphatic ✔ is drains capillaries vessels vessels. B.3.3.8 uid Some the lymph with these Figure tissue capillaries lymph p system capillaries. capillaries lymph system vein the thoracic circulatory stomach the body with the increased oxygen needed for aerobic respiration. and, 3 like the It also is cells liver, led and people is with – to you with white lymphatic have removed lled their live Some spleens without cardiac each blood tissue. have can The blood. output minute. hear t beats volume of This per is is the achieved minute blood volume by of out of in increasing increases), pumped blood and the dm the increasing hear t with pumped hear t the each rate out (the stroke beat of the hear t number volume of (the increases). it. cardiac output (volume hear t rate stroke volume blood in 3 of blood from The in hear t extra blood dm per is = minute) volume t hat (volume of 3 pumped of stored t he per × minute) blood in (beats coming liver and into of t he spleen hear t dm per circulation when at pumped out beat) during exercise is rest. 142 835292 CSEC HSB Unit B Topic 3.indd 142 08/01/2015 16:07 The circulatory system The Practical The beep This is a circulatory system Activity test popular oxygen to names: beep way support test, to test aerobic bleep the efciency respiration test, shuttle of during runs, the heart and exercise. multi-stage It lungs has a tness in providing variety of test. Requirements ● T ape ● two ● CD measure markers player, 20 test with Y ou apart. 1 Find a 2 Warm only flat up with 20 beep metres test apart app, continuously runs, beeps laptop surface 5 to 10 are with and between sometimes that continue for set a running These pre-recorded should rule running a program with beeps involves metres metre person phone pre-recorded This or per played this mark at activity two minutes called by if points doing set two points shuttle intervals you that are are some in that runs, of are exactly kept in time time. good exactly jogging are health. 20 and metres apart. stretching exercises. 3 Start one the foot beep test software. on just over or the At line. each beep, you The beeps are need set to so have you at will least start to −1 move until 4 at 8.5 you After a km hear while, . h the If you are too fast you will have to wait at the line beep. there will be a double beep which indicates the speed is −1 5 increasing by rest test. of When read the you your before miss your km the fitness failing oxygen 0.5 to h beep score keep body . on from up can This is will two the your absorb now happen consecutive program score. during or This at regular occasions, app. The score exercise. It is is intervals stop highest the the test level maximum known as the for the and you reach volume VO of max 2 3 and 6 is Warm Try the measured down test by and Bleep in cm doing compare 3 oxygen some your per kilogram stretching level of per minute (cm −1 kg −1 min ). exercises. tness with others. Test 54.5 3 Fitness: Next cm beep: 2 sec Speed: -1 kg -1 min 13.5 km/h 20 p Figure B.3.3.9 measure their These aerobic two students are doing shuttle m runs to fitness 143 835292 CSEC HSB Unit B Topic 3.indd 143 08/01/2015 16:07 The circulatory The system Written The output of of a student measurements q T able heart were while system Activity the Measurements circulatory at made resting are in rest of the and T able and during heart during rate some exercise and the cardiac strenuous output exercise. The B.3.3.2. B.3.3.2 At rest During strenuous exercise −1 Heart rate / beats min 3 Cardiac output / exercise organs and cardiac output strenuous q T able 5 25 min there organ 160 −1 dm During 72 are changes systems. that ows T able through in the distribution B.3.3.3 the shows organs of the the of blood to body at rest of Percentage at of cardiac Percentage rest Brain output Skin of the digestive system Kidneys of during 15 6 3 26 2 4 20 80 5 5 Bones 4 1 Others 4 2 muscles Cardiac muscle 1 data Calculate in in the heart T ables the B.3.3.2 student’s and stroke B.3.3.3 volume cardiac exercise 3 20 Skeletal the during B.3.3.3 output Use the and exercise. Organ Organs different percentage to (i) answer at rest, the and following (ii) during questions strenuous exercise. 2 Summarise when the someone significant does changes strenuous in the distribution Calculate the a 4 the organs rate listed of a blood at rest, flow and blood that occur exercise. 3 3 of in b dm −1 min during that flows exercise. through Present your each of answers in table. Draw at a rest Figure bar graph to and during exercise. B.3.3.10 as compare this a the rate Consider good way to of blood drawing show flow the data through bars like the organs horizontally as in this. Skin 0 0.1 0.2 0.3 0.4 0.5 0.6 3 Rate p 5 Suggest T able examples Figure of the of blood flow/dm 0.7 0.8 –1 min B.3.3.10 organs included in the category ‘others’ in B.3.3.2. 144 835292 CSEC HSB Unit B Topic 3.indd 144 08/01/2015 16:07 The circulatory system Heart disease Questions 1 Describe goes 2 from Make 3 a pathway lungs table to that shows that supply Explain why the the left vena side 4 Explain 5 a in why Describe the must be the blood in and organs each exactly in the back the organ to the body and flowing the circulation into same the as it it the names of the away. right the when lungs. and take system side volume of the heart entering the vein. have structure blood muscle to of pulmonary arteries by the blood volume cava the taken cardiac vessels in 6 the thicker of walls capillaries. than b veins. Explain the role of capillaries in body. State four ways in which blood returns to the heart from the systemic circulation. 7 Explain 8 Name B.3.4 how an artery Heart Cardiovascular Caribbean the lymph heart as that all formed. contains deoxygenated blood. disease diseases in and is are other the parts circulator y Learning most of the system. important world. Included cause These in this are of death all the categor y in diseases of By the of disease the heart disease (CHD), heart failure, heart valve disease be of and define the explain disease ● explain effects Coronar y hear t disease angina – pain you hypertension in the of atherosclerosis arteries causes heart and attacks includes: ● ● term how develops heart topic to: strokes. ● Coronary this able are ● coronary end should outcomes across t he chest, lef t arm and shoulder caused describe the role of artificial by pacemakers. insufcient ● coronar y some blood getting t hrombosis cardiac muscle – is a to t he hear t blockage star ved of muscle occurs blood in and a coronar y dies –t his ar ter y is a so hear t t hat attack. Key terms ! Figure 3.4.1 muscle The in shows t he blockage cardiac lef t t he ventricle stops muscle. coronar y t he This and blood tissue ar teries a place owing dies and supplying (C) into t his where an a in of blockage capillaries results area a cardiac has supplying hear t occurred. a region of Coronary condition one attack. or more Atheroma arch material of heart caused on disease by a coronary A deposit the lining A blockage in arteries. of of a an fatty artery. aorta right coronary artery left coronary artery A t Figure B.3.4.1 The heart showing coronary B arteries. C is A blocked blood branch at C leading cardiac so to of the left coronary interrupting the death of flow artery of surrounding muscle 145 835292 CSEC HSB Unit B Topic 3.indd 145 08/01/2015 16:07 Heart The disease circulatory system Atherosclerosis Key term ! One of t he most atherosclerosis Atherosclerosis The process fatty material is deposited lining of of blockages material, in coronar y par ticularly ar teries cholesterol, t he inner wall of t he coronar y ar teries (Figure B.3.4.2). These artery with fatty endothelium streak develops wall of on the plaque the and artery space develops narrows for plaque the blood p Figure Tiny B.3.4.2 par ticles ar teries become widt h and (see of less able pressure. disturb partially The blocked artery cardiac lies on muscle section coronary the which is of blue. outer deposit a large very wall of part little of the plaque of the space artery (orange) artery. the clot. clot A in flow to flow for through (red) is blood to cardiac to in of 3.4.3). reduce in roughen ow tears t he or phagocytes t he properly plaques by and Wit h t he plaques. t he lining to it cholesterol breaks form forms time, space and of in for ‘foam blood t he cells’. to become t he in of This t he walls increase of t he ow. less to coronar y cells lining plaques recoiling increasing to t he plaques t he Ar teries stretching blood to artery artery distribute enter at heroma and begin deposited blood clots the elastic maintain ar teries chance t hat and blood and blood will clot is coronar y called ar ter y a t hrombus t hat reduces and or coronar y stops t he t hrombosis ow of blood is to a blood an area of muscle. is The cardiac fatty acids) muscle and it does does not not receive have its any oxygen carbon and dioxide nutrients carried (glucose away. and The muscle Cardiac muscle (bright the muscle is B.3.4.2 coronary may engulfed and smoot h blood a star ts to respire anaerobically and produce lactic acid. capillaries cannot supplying The t he a off rough a blocking There blood be in is Inside tissue red) wall in Some material function t he cardiac the are of artery. surface fatty may to body. Figures t he Calcium cross travel t he ar teries A t hat t hroughout accumulated B.3.4.3 Atherosclerosis breaks lining block a deposits arteries. Healthy Figure is deposited atheromas smooth p is in called the causes fatty by in which common where function correctly under t hese circumstances and may die. This (×7) coronar y When such ● someone in t he discomfor t ● sweating ● t herefore hear t likely attack t hey to cause usually a hear t have a attack. variety of symptoms, and of under t he breastbone (clavicle) and down t he lef t arm nausea vomiting breat h and anxiety weakness. Some hear t attacks increases t he have hear t lives. to had To do reduce Risk t he is hear t a are chances t hey risk of but have have from recovered received having heart ot her are a not. hear t and hear t Prompt attack. gone treatment anot her component Among many sur vival coronary genetic attack. of fatal, of attacks t his factors There a a chest, and shor tness ● has is as: pain ● t hrombosis on and medical Many to lead have attention people long who and changed active t heir lives attack. disease t hat makes factors t hat some people contribute to more likely coronar y to suffer hear t 146 835292 CSEC HSB Unit B Topic 3.indd 146 08/01/2015 16:07 The circulatory disease t he are risk of a system diet increases lack regular High they blood have are it t he high risk and no of and they saturated high fatty fats, blood deposits they smoking know symptoms when in and smoking, pressure, which high developing in increases blood t he disease pressure, ar teries and a exercise. pressure smoke there is at herosclerosis which of t hat Heart of have they high their are can, blood blood two serious with risk factors. willpower, pressure pressure and taken give most (see it People up. However, people Figure know discover they B.3.2.9). Hypertension If blood pressure The normal and 10.7 13.3 kPa kPa above for consistently pressure diastolic increases pressure below is blood gures in risk kPa is of high, a (120/80 t he 17 .3 for t hen young in a mmHg). A to be is has about diastolic cardiovascular considered person adult kPa pressure problems, ver y hyper tension. 16.0 and serious a (see systolic ✔ Study Very diastolic t he case Treatment Hear t ● disease Balloon small heart is how vessel vessel so Hear t bypass from t hat Some operation. to – t he opens t his in During t he are or suffering in of at heroma from The a and stroke out. body need surger y, blood carried to a ow out is by-pass or of each putting or increases hear t t he blood pressure have and had last year. You hypertension you taken their may to learn within have them; this if topic to the explain so, this really will well. t he attack. t he a of ow piece blocked such body. it t he of t he of used. ver y t he par tially t he par t diseased blood. blood section of by-passes in (‘hear t-lung’ Large (a be into reaches stretching pump t he t hrough rate may cat heter around cat heter taking more surger y a balloon t he mechanical t hrough cases pushed increases two a inated, involves one, is por tion balloon This severe wit h cat heter balloon The In involves diameter procedure t he dr ugs. procedure vessel. people make operations ● it development various mm blocked. elsewhere ar ter y. used until by t his 1 coronar y nearly is – about t hat t he angina treated closed many about friends disease ination tube) diseased ● stimulates developing of know Ask family help of people mmHg). excessive alcohol, take little exercise, or eat a high fat and/or high salt diet. chances few hypertension. study High blood pressure is more likely in people who smoke, are overweight, drink Hyper tension tip above vessel coronar y one machine) numbers of is t hese year. Heart transplant – in ver y serious cases a heart transplant may be carried out, but the number of these is limited by the availability of donor hearts. Articial Some pacemakers people pacemakers. under Each t he t he demand is skin atrium impulses or problems made patient’s right electrical hear t operation takes need to be tted approximately an wit h ar ticial hour and is performed anaest hetic. pacemaker under into local wit h The when up of and and t he ar ticially t he hear t a batter y-powered two electrodes right and misses ventricle. conducts a beat. pulse which The t hem are generator placed pacemaker to t he implanted t hrough veins generates cardiac muscle on p Figure B.3.4.4 inserted into a An artificial person’s pacemaker chest 147 835292 CSEC HSB Unit B Topic 3.indd 147 08/01/2015 16:07 Heart The disease Maths T able the q B.3.4.1 shows Americas T able skills in circulatory system 2 deaths from cardiovascular disease in ten countries in 2010. B.3.4.1 Country Population Deaths T otal from cardiovascular of diseases all number deaths from 1995 causes Barbados 283 000 504 1800 Belize 324 000 325 1300 Cayman Costa Islands 50 000 43 270 4 805 000 6 300 21 000 11 271 000 34 710 89 000 72 000 183 572 795 000 2 079 6 300 109 000 311 700 1 337 000 4 160 13 000 318 000 000 823 360 2 656 000 Rica Cuba Dominica Guyana St. Vincent and the Grenadines 2010 Trinidad and Non-communicable T obago (2008) diseases USA Communicable diseases These Injuries and much Ill-defined p Figure B changes 3.4.5 in 2010 of Pie charts percentages in death the in cannot be compared easily as the populations differ so size. causes to of show four the 1 Calculate between 1995 for each country listed in T able B.3.4.1, main a causes gures accidents the crude the population death the deaths rate, which is the number of deaths per 100 000 of and of each country; Caribbean b 2 Display the countries The number countries 3 How this 4 5 results are of as from easy cases they would cardiovascular of your to see of you use calculations at a coronary become disease more as so a percentage comparisons of total between deaths. the ten glance. heart disease is said to increase in developed. statistics of deaths in different countries to test statement? Suggest how you would organisations to and coronary heart List the factors, developing Case find out use data whether from there national is a and international correlation between smoking disease. other coronary than heart smoking, that increase the chances of disease. study Hypertension The ✔ Study tip Non-communicable all by the diseases organisms viruses. There that such is Unit D.1 and diseases are as not t he Americas, t he ten Organization cause mor tality almost from maintains two t hirds diseases t hat non-communicable of all deat hs worldwide. linked to hyper tension is In leading causes of deat h in men and one of women. caused more diseases D.2. Healt h currently are bacteria much non-communicable World diseases and about in Hypertension is a persistent raised blood pressure. The WHO denition of hypertension is a systolic blood pressure that is always equal to or above 1 40 mmHg (≥ 1 40 mmHg / 18.7 kPa) and/or a diastolic blood pressure that is always equal to or above 90 mmHg (≥ 90 mmHg / 12.0 kPa). 148 835292 CSEC HSB Unit B Topic 3.indd 148 08/01/2015 16:07 The circulatory system Hyper tension is women. High blood a children and Heart risk factor of disease t hat affects bot h men and ✔ pressures teenagers in have t he even been found in sur veys many different tip Caribbean. as of Exam of You Samples disease populations across t he world suggest should they know may be all these used in symbols exam t hat questions: up to 30% 140/90 have of t he mmHg. t he One condition. hyper tension 140/90 adult wit h population t hird One of in dr ugs, suffers people t hree fail to from sampled people keep do who t heir blood not are blood pressure know being above t hat treated pressure > greater than ≥ greater than < less than ≤ less than t hey high blood cer tain pressure of Afr ica, of to do diet to so have of decreasing blood of t he t hese decreases, and volume of work do. to falls. salt blood does t he and again Beta-bloc kers These t he lose blood are dr ugs t he suffer from it. a t hat – is many of cases If or equal to If doctors in ow to of called pressure t hird type t he falls of hear t dr ug rate about use them especially BMI and in your when writing hypertension. in treated r isk t hey style and of to can c hanges dr ugs. resist ance hard and t he decreases t he wit h ar ter ioles increase hear t t he so to t he volume t he has prescr ibed and are c hanges t he so This as also Americas, t he t hen life As blood ur ine. be prescr ibe diuretics, t heir by ar ter ies blood. pump a can answers, remain reduce smoke, can t he t he 65 common countr ies could t hese of while groups. t hem pressure t hey t hat, age In more et hnic in blood in reduce it most t hese t hen dr ugs, people from ot her muscles reveals men, difcult. need USA , signicantly active. to not Ot her t hat of t heir effect, relax t he adults would of ten resist ance hear t hyper tension. hear t ’s desired t he t he many more is of in pressure lower t hat in men t han cent whic h can dr ugs pressure water per in discovered blood becoming alt hough t han have t hough people and quit not Some 40 medications, Some common descent high even including women t han have undiagnosed, tr y of more African more estimated low-cost is hyper tension populations t heir countries, propor tion sur veys deat h. to below You from In equal mmHg. Data higher or for less reduce power of t he contractions. Even though people with high blood pressure take dr ugs, they may still have hypertension. It is far better to not to smoke, take plenty of exercise, eat healthily and drink alcohol in moderation or not at all. This reduces 1 in 3 adults suffer 1 in 3 adults with from hypertension the chances of developing hypertension. 1 Questions know 1 Dene 2 Explain 3 What 4 t he term why are Explain many t he how people dangers of do not know t hat t hey have Suggest reduce 3 hyper tension? hyper tension ways t he in can be this do not disease which number of governments cases of 1 in 3 adults cannot teating keep it their hypertension under 140/90 treated. and medical aut horities Figure B.3.4.6 shows the This isotope significance of diagram hypertension. can Isotope diagrams present data are often used to hyper tension. way 6 hypertension have hyper tension. p 5 they hypertension. and are on health in commonly a very used in visual official Design a health education poster to show the importance hypertension. reports, posters and web sites 149 835292 CSEC HSB Unit B Topic 3.indd 149 08/01/2015 16:07 Heart The disease circulatory system Questions Talk about Caribbean countries ? successfully diseases of cases illness reduced diseases malnutrition. diseases controlled and of But remain and early 1 Define the if 2 Explain how plaque is 3 Explain how a attack 4 Explain the 5 A of the the due to or a major number cause of group their of try to friends this and wall of an artery. heart may occur. role of an artificial pacemaker. with people aerobic of fitness. different both genders Explain exercise how who you regimes are not could as physically use ways to this fit group improve wish of to improve people aerobic to fitness. cardiovascular and your the reduce this be left up Summary families? The Discuss in should to should individuals formed to death. do prevalence disease disease. cardiovascular anything, governments cardiovascular infectious compare What, term have your circulatory system family, teachers. ● Diffusion small ● Very is a small means since their there Large and is ● too Blood are need great is a from small the cells produced humans, not released suitable surface acts for have large the as for area: their gas transport volume within ratio exchange oxygen to a surface small enough in liquid as a very enter and which surface diffuse to provide area: volume ratio enough oxygen for the to blood liver are and blood to are shape many to and cells acids, whole is from in distances cells and from the throughout white glycerol, solution body. as is heat. in in gas the blood amino the is the Urea the endocrine in Oxygen transported transported body cells that is blood glands acids, blood plasma. a to plasma transported waste the where in Water red is substances kidneys. they are organs. adapted are blood fatty body a for transporting relatively molecules and red fat, dioxide with form cells bacteria of the transported cells the respiring transported the target because the diffuse. glucose, carbon their haemoglobin to to plasma. intestine the are system lungs composed throughout biconcave nucleus in minerals and Hormones engulf large surface oxygen in such and White a surface transport tissue distributed ● a for vitamins a is surface Nutrients, Red only body. like suspended blood ● is body. exchange ● the surface Humans are that have body enough animals, the whole ● process organisms that throughout ● slow organism. of large oxygen surface haemoglobin. for as they have diffusion, Oxygen no combines with oxyhaemoglobin. part digest of the them body’s inside defence system: vacuoles; phagocytes lymphocytes secrete antibodies. ● ● The heart is a muscular The heart is a double circulation to the lungs circulation to the rest Humans in one have a complete organ pump and of double the made as the one other entirely pumps pumps of blood blood cardiac muscle. into pulmonary into the systemic body. circulation circulation almost side of the as blood flows through the heart twice body. 150 835292 CSEC HSB Unit B Topic 3.indd 150 08/01/2015 16:07 The ● circulatory system The heart thin walled has ventricles. and the needed lungs, the ● left The this thick are for ● blood allow tissue fluid easily into Veins have one the the thinner in on its cells During arteries, forms which are no have The a a Tissue blood a the is and clot a or heart fluid the heart’s all and right but the is The than pressure to thicker the wall pacemaker. heart fitted into the elastic to than This contract. under the arteries. heart If skin These contracts fibres tricuspid recoil close when to pass when the into to have arteries and push between prevent easily atria valves at the contract relax to ventricles. have from dioxide the backflow ventricles ventricles the These Carbon to Semilunar open arteries vessels. valves) contract direction. artery the cells. than arteries have stop traps of the very the and thin walls blood wastes into pass back that red is (not thickens cells the veins) the so areas tissue to to and many help is start of dries blood to is the clotting have form to ions a scab. the lining fatty and no into molecules of material the process atherosclerosis. people wound, small calcium This atheroma the are converted The damage material. lining seal are protein. causes fatty hypertension withstand that Platelets chemicals with This of to ensure prothrombin fibrous blood pressure. arteries a have to immediately of enzyme which not pathogens. release deposition and of do valves heart. clots entry This that the they molecules fibrin blood to blood the blood as semilunar back into of When the ventricles oxygen broken the lining of increases are risk of attack occur. may all some fluid. This back small are full the cells enters flows into of such in blood in a in the lymph walls body, the thin Lymph concentrated as the which within artery to idea There that they in of walled secrete these it vessels. drains lymph of If cardiac into which vessels through regions and reduces supplying form flows respiratory lymphocytes arteries much capillaries blood. of clotting coronary through the swellings pathogens, nodes the fatty occurs surrounds by of thrombosis system that attack is deposited colourless Lymph lungs pressure. blood process, high capillaries, nodes the condition. lymphatic to in it flow muscle is is the journey promoting development blood much a are the to body. has pressure fibres. the from thrombin. mesh symptoms the blood in this enzyme in They and fibrinogen Hypertension by the atria into capillaries. walls loss that blood greater stimulate relaxes, arteries, and pressures. forms is high pulmonary surrounds blood of of The distance much pacemaker (bicuspid when smallest blood way active that blood back nutrients of atrium elastic its the the prevent fibrin ventricles. short rest is ventricle under heart travels vessel converts ● it and blood process. and valves a the the body artificial heart close into that blood right an the flowing are which fragments ● aorta blood Capillaries When left two a deoxygenated to the impulses maintaining ensuring the allow flows ● when ventricles blood high ● muscle the of the the the atrioventricular prevent ● of and to ● of stretched; base pumps blood and blood heart. out along in reason The of why atria pump around electrical the walls node any flows blood pumps blood explains regular fails Blood ventricle ventricle two to disease ventricle. stimulate ● contract right sino-atrial emits chambers: they pump which right four as The to Heart of the lymph the digestive body prone system. antibodies. 151 835292 CSEC HSB Unit B Topic 3.indd 151 08/01/2015 16:07 Practice The Questions 9 Practice Which substances are dissolved in circulatory human system blood Questions plasma? Section 1 What does t he term A The relaxation B The closure C The contraction of systole of a a refer 2 The What A carbon B glucose, opening does t he chamber valve of of a a in t he of hormones C sucrose, oxygen D brin, t he valve in blood t he vein from Deoxygenated C Oxygenated D Deoxygenated t he of t he Which carbon occurs A t hrombin Which blood blood of t he from from blood following A small lumen B t hick elastic C presence D high A person B brinogen C red D platelets blood to t he rest during is of blood who is at salts clotting? to is conver ted prot hrombin cells stick to brin toget her a meshwork t he t he hear t lungs to to t he t he from t he body to is not a feature of B lungs. hear t. t he a The diagram below shows t hree types of cells found hear t. t he blood. ar teries? walls valves pressure A consumes risk coronar y a diet rich in fats and does B ast hma C haemophilia C not Name t he cells labelled A, B and C. [3] from: hear t B State one function for each of t he cells named disease b Sarah It 1 above. pricked star ted [3] her nger bleeding for a wit h a needle moment and while t hen sewing. stopped. diabetes i) ii) Which of t he following is a characteristic of t he What cell t hat allows it to carr y out its function A B No round Tissue t he uid is bleeding. impor tant to stop works bleeding? in her body [1] to [4] for t he transfer of nutrients cells. shape. Identify t he name of t he process from t he tissue by which nucleus. nutrients Contains many molecules of Small uid to [1] size. ii) is move haemoglobin. cells. t he role of platelets in t he ght Explain how tissue uid is formed. [3] blood? 2 to her process oxygen? i) What caused t his of to A how red c transpor ting process Explain stop blood A blood conver ted form in 6 and of ii) D proteins carr y? hear t i) exercise C and dioxide hear t. in 5 glucose hear t. 1 D and salts body. B A and hear t. Section 4 haemoglobin hear t. chamber pulmonar y Oxygenated t he 3 dioxide, to? 10 D A A The diagram below shows t he pat hway of blood between infections t he B to transpor t C to reduce D to help carbon blood hear t, lungs and ot her body organs. dioxide pressure LUNGS 7 Which of in blood t he clotting following is tr ue about tissue uid B and C lymph? Tissue A Contains B Is red uid blood Lymph cells Contains white blood cells Valve formed ltration blood from arteries C Has high pressure D Contains a water dissolved 8 by Which of t he of Is formed in the lymph nodes Has and a low Contains pressure white blood cells A nutrients following blood vessels have t he D lowest pressure? A ar teries B ar terioles C capillaries D veins OTHER BODY ORGANS 152 835292 CSEC HSB Unit B Topic 3.indd 152 08/01/2015 16:07 The circulatory a i) system Name and b Copy two and types t he D. Practice blood blood t he table vessels Structures Presence labelled A, B, C 4 The diagram below shows t he str ucture of t he hear t. [4] complete of vessels Questions below found in which t he compares body. Artery [3] Vein or F absence Blood valves pressure Relative of of High thickness wall A c The circulation into two pat hs of – blood in t he pulmonar y body can circulation be divided and systemic E B circulation. i) Explain blood ii) d State Andre was amount i) what involves. two pat h fried by foods Explain why advice? [2] of t he circulation of [2] substances advised of each his he you transpor ted doctor was to by reduce blood. [2] t he consuming. t hink t he doctor gave t his C ii) Suggest T WO ot her changes t hat Andre can D make to improve system. t he healt h of his circulator y [2] a 3 Blood is one tissue in t he body associated wit h State A circulator y i) and State two functions of blood. Fill in t he blanks in t he following The liquid par t contains of water transpor t mainly cells to State t he Copy blood and is called dissolved d substances . , defend and State t he complete and t he of names body The red while such as blood t he white t he Explain how effect blood . following table about t he type of blood t hey carr y. blood vessel e t hat Sheldon the atrium blood lungs to from through the atrium ways in t he pulmonar y t he aor ta. exchange uid. t he four chambers He diagram. of t he hear t, t he walls of hear t var y has on t he t he [4] upper in and lower t hickness pressure of and blood t he for [4] born loves to wit h play a hole but in gets t he tired septum easily of and his suffers what is happening symptoms he is in Sheldon’s hear t experiencing. to [3] a Explain these why a large multicellular organism such as left human, needs a circulator y system unlike small veins body blood to through the these ows right Identify par t c of organisms, which ar ter y t he blood differs from carried t he ii) in of in which substances [2] capillaries between are adapted blood and and circulator y such as ONE tissue an system. hospitalised af ter (coronar y amoeba. t hat [3] is [2] suffering from a hear t Explain t hrombosis). what happens attac k. [3] One factor r isk for at herosclerosis. [2] ways is organ veins in blood ONE t he Sharon i) two in ows the Aorta State t he t he t he was t he attack d valves artery Deoxygenated two t hese fatigue. cause b State of on t his single-celled Pulmonary of [4] a c labelled blood 5 from of F circulation. [5] Description Oxygenated to chambers cells against C Explain Name impor tance labelled from vessels valves [2] hear t. b two blood. and help t he paragraph c about It of [2] [2] hear t. ii) names B system. b a t he t he for tissue iii) explain how around t he Suggest T WO should hear t it attack. hear t Descr ibe affects body. make a hear t attac k t his t he a is process transpor t and of blood [5] lifestyle to dur ing changes reduce her t hat chances Sharon of anot her [2] 153 835292 CSEC HSB Unit B Topic 3.indd 153 08/01/2015 16:07 Unit B The skeletal system B.4 Learning By the end B.4.1 outcomes of this topic Bones be able identify the main bones the and their uses of the skeleton can see from Figure B.4.1.2 how impor tant t he skeleton is for us. The of skeleton ● skeleton to: You ● the you Functions should of has several functions. skeleton relate the structure of the Support skeleton to its functions The ● relate the structure of skeleton organ typical bone to its provides t he framework for t he rest of t he body. All t he ot her a systems wit h t heir sof t tissues are suppor ted by t he bones of t he functions. skeleton. The skeleton also gives shape to t he body (see Figure B.4.1.2). Movement The bones ar ticulate provide wit h a each solid str ucture ot her to for provide muscle levers to attachment. allow Some bones movement. Protection The hard bones e.g. t he t he cranium ribcage protects t he of provide protection protects t he t he skull spinal cord. hear t protects from and t he physical lungs, brain t he and damage pelvis t he to our protects ver tebral sof t t he tissue, uter us, column Breathing Intercostal muscles movement of t he for t horax Manufacture Stem cells form blood t he move breat hing of blood wit hin cells t he ribcage diaphragm, t he and in t his and up and increases down. and Toget her decreases wit h t he volume of out. cells red bone marrow t hat is inside some bones divide to platelets. Storage Bone tissue ot her t han blood p Figure B.4.1.1 A sports are a sporting a ner vous in blood store of hardening kept in calcium. bones constant tissue plasma for as it and is sending plays This mineral teet h. needed impulses impor tant roles element is Concentrations by cells from in for one blood used of muscle ner ve to for functions calcium in contraction anot her. t he and Calcium clotting. physiotherapist Yellow treats is bone marrow stores fat. injury 154 835292 CSEC HSB Unit B Topic 4.indd 154 08/01/2015 16:09 The skeletal Figure system B.4.1.3 Bones shows t he bones of t he human of the skeleton and their uses skeleton. cranium of skull orbit mandible cervical clavicle (collar scapula vertebrae (first two atlas and are bone) (shoulder axis) blade) sternum (breast rib (articulates thoracic bone) with vertebra) humerus lumbar vertebra radius p Figure B.4.1.2 The virtual body. Not ulna only does functions, our it skeleton also gives do all shape these to the sacrum body carpals coccyx metacarpals phalanges acetabulum forearm bones uncrossed (palm (socket into head femur of which fits) forearm bones crossed (palm up) down) femur patella (knee cap) ✔ Exam tip fibula T ake care when writing answers tibia about the nervous the system. vertebral column) spinal the skeletal with Do not column the column spinal system is cord (or spinal made is and the confuse spinal cord. of The bone; made of of central nervous tarsals tissue and is part the metatarsals nervous system. phalanges p Figure B.4.1.3 The human skeleton 155 835292 CSEC HSB Unit B Topic 4.indd 155 08/01/2015 16:09 Bones of the skeleton and their The uses suture parietal Major bones of the skeletal system skeleton (right) frontal There are ve different areas of t he human skeleton. temporal 1 The skull, comprising t he cranium and t he mandible (lower jaw) (FigureB.4.1.4). orbit 2 The ver tebral 3 The ribs 4 The girdles and column sternum (Figures (Figure B.4.1.5, B.4.1.6 and B.4.1.7). B.4.1.8). upper jaw – t he pectoral girdle (Figure B.4.1.9a); t he pelvic girdle (FigureB.4.1.9b). occipital position of right ear 5 mandible (lower The The jaw) limbs central comprises p Figure B.4.1.4 The human or axis t he (Figure of is t he skull body and B.4.1.9). suppor ted ver tebral by column. t he The axial skeleton, girdles which and limbs form It made from t he skull appendicular neural appendages spine: for neural arch: spinal cord skeleton. tendon Axial protects skeleton Skull neural canal: spinal cord carries The cranium many protects individual t he bones delicate fused tissues toget her. of The t he brain. joints is between t hese bones can transverse process: be for tendon seen as anot her suture in a way lines t hat in Figure makes B.4.1.4. t he joint The bones between have t hem grown ver y into rm. The one at attachment bones centrum: body of of t he skull continue to make red blood cells t hroughout our lives. the The mandible (lower jaw) ar ticulates against t he cranium and allows us to vertebra feed p Figure B.4.1.5 A generalised and to vertebra Vertebral 7 cervical atlas vertebra axis vertebra speak. (neck) The for column ver tebral t he bac k column muscles gives and suppor t protects to t he t he body, delicate provides tissues of att ac hment t he spinal cord. vertebrae There are B.4.1.6). 12 ver tebrae ver tebra in a has However, ver tebrae have positions along spine. B.4.1.1 thoracic 33 Eac h and t he t he human, t he slightly differences These in alt hough general some str ucture different functions functions str ucture of are are fused shown in according summar ised ver tebrae (Figure Figure from in t he B.4.1.5. to t heir Table nec k vertebrae (cer vical), (connected on each to a c hest (t horacic) and small of t he bac k (lumbar) are shown in rib Figure side) a B.4.1.7. cervical A b A thoracic E B E D D 5 lumbar (largest vertebrae B and C strongest) C c 5 sacral lumbar A vertebrae E (fused together forming B the sacrum) 4 D caudal vertebrae C (fused together forming the coccyx) p Figure B.4.1.6 The human vertebral p Figure B.4.1.7 Cervical, thoracic and lumbar vertebrae column 156 835292 CSEC HSB Unit B Topic 4.indd 156 08/01/2015 16:09 The q skeletal T able system B.4.1.1 Bones Summary of the vertebral column and its of the skeleton and their functions thoracic Vertebrae Number Cervical Special 7 First Thoracic 12 Lumbar Sacral Caudal Ribs (coccyx) and are of Articulate 5 Support 5 Fused 4 Greatly vertebra features two nodding uses the the (join) the atlas and axis which allow rotation and head with upper together to reduced the ribs body – support in large, the humans; to withstand pelvic no stress girdle special function sternum rib The 12 pairs of ribs, toget her wit h t he sternum (breast bone), form a sternum (breast bone) rib protective about t he cage around breat hing t he hear t and lungs. movements t hat draw They fresh are air also into vital our in lungs and force p Figure ribs, stale t he of air out of centr um ribs are our of a joined lungs (page t horacic to t he 104). ver tebra sternum The head (Figure by of each B.4.1.8). car tilage. The rib The ar ticulates uppermost lowest two pairs B.4.1.8 sternum not joined; for t his reason t hey are called “oating of and limbs connect girdle is made up of t he scapula (shoulder blade) and (collar bone) B.4.1.9a for clavicles be used on each side of t he that bone to the girdle shows muscle give for t hat t he scapula attachment suppor t to t he manipulative and a is t here socket shoulders the Bones leg that bones to the body. so to for t hat provide t he t he a broad, humer us forearms to are t column. at into. free and The can tasks. a Pelvic arm t he vertebral surface Bones upper column. connects Figure girdle the girdle pectoral clavicle terms ribs”. Pelvic The of vertebrae pairs vertebral Pectoral arrangement thoracic ribs Pectoral Girdles The and wit h ten Key are cartilage bringing Pectoral girdle and forearm b Pelvic girdle and leg girdle pelvis The pelvic t hat grow girdle is formed separately in a by t he foetus. fusion They of fuse six not bones only scapula wit h each giving a ensures ot her girdle t hat but t hat t he also is wit h rigid t hr ust t he ve (Figure developed sacral ver tebrae B.4.1.9b). by our This leg muscles femur humerus passes to t he rest of t he body. Limbs The ar ms and legs are built on t he same patter n, ulna patella called a pentadactyl limb. This is because t here are radius ve digits on t he cor responding end of each bones in t he limb. front In and Figure hind B.4.1.9, limbs are fibula carpals shaded in t he same t he one way. Note t hat t he radius in (8) t he tibia metacarpals forear m is whet her t he palm nearest is t he tur ned t humb upwards regardless or of downwards. tarsals of (7) fingers metatarsals phalanges of p Figure B.4.1.9 Limbs and girdles toes compared 157 835292 CSEC HSB Unit B Topic 4.indd 157 08/01/2015 16:09 Bones, cartilage and The joints skeletal system Questions 1 a State to fulfil 2 Name 3 What 4 The Figure 4.1.10 A physiotherapist doctor explain the this patient has with two the are of the bones the able to Suggest the skeleton. functions that common of of move one allow name skull you are of over have the the not each how the skeleton works listed. to rotate and nod. mandible? by other of Explain head fused advantage b the time without a baby is damaging born. the Instead, baby’s this. problem 5 that the is brain. and functions three bones they p five his Use the A E information in Figure B.4.1.5 to name the structures labelled lower to in Figure B.4.1.7. a, b, given the c back 6 State the Learning By the end this topic name back. B.4.2 outcomes of the lower Bones, be able describe the structure of skeletal skeleton tissues: compare the functions and forms joints of bone and cartilage are is composed bone and of two cartilage. main These tissues tissues known have t he as skeletal same tissues. basic consist of cells wit hin an extensive matrix of tough str ucture. collagen bres describe ot her bone t he the structure ways bone structure t hat t he matrix consists which t his in cells produce. to and the is of bres formed. hardened Spongy by bone calcium consists salts. of There str uts of are bone of separated long material cartilage two a that of In bone ● column cartilage and ● and vertebral bone They and the the These two cartilage of to: The ● region you Structure should to relate by sof ter bone marrow. Compact bone is wit h a much more solid, its functions consisting of tightly blood lymph packed cylinders, each central space lled wit h it and vessels. You can see t he str ucture and distribution of performs t hese ● identify joint the and different state their types the compare car tilage, the ligaments and t he section between A bone bones. are transverse showing section also systems. photomicrograph of t he femur in Figure B.4.2.4. 4.2.4 in t he t he cells external is not ears, as t he hard end and of is t he much nose bronchi. These are all places where and exibility it the (x100) vessels B.4.2.4 car tilage and protects ot her. blood bringing and Long bones It vessels such as discs bones is in so bone such between t hey smoot h glucose, hormones in t he to as not provide tissue amino do t he wear vitamin D away t he calcium is (see Unit made constant ar ticulation cells and are by frictionless providing acids, ver tebrae wit h phosphate, B.1.1). There are car tilage. shows t he tissue. It microscopic also shows str ucture t heir of two distribution types in a of bone limb tissue bone. bones the Compare with many Figure of of each nutrients, blood Figures Haversian is and Car tilage between no B.4.2.1 ends against and compact trachea The car tilage. oxygen, Figure material Car tilage r ubbing There of t he tendons. of Figure in characteristics required. p t he exible. suppor ts of tissue body more ● of locations In in types of B.4.2.2, B.4.2.3 and B.4.2.4 show different views of t he humer us this drawing in from t he have similar a joint upper wit h arm and t he femur from t he shapes, but t he femur has more t he marrow-lled pelvic cavity. girdle. This These gives a a limb upper Notice pronounced bones str ucture leg. t hat are is not head solid, strong t hat yet t hey t hat but forms contain a light. 158 835292 CSEC HSB Unit B Topic 4.indd 158 08/01/2015 16:09 The skeletal The system features of t he Bones, femur shown in Figure B.4.2.4 are summarised A rounded pelvis. head This t hat allows forms t he movement ball in of t he t hree ball and socket joint wit h The head is wit hstands made of stresses spongy t hat bone operate all is light but strong as made it directions. T issue of The long shaf t of t he bone is hollow; t his Cartilage reduces t he chances of across t he whole ● The outer par t The rounded The surfaces of t he lower shaf t end is made forms t he of compact knee joint bone wit h which t he tibia is ver y and hard. found ligaments, t he of t he such femur as t he provide cr uciate sites of attachment ligaments t hat for extend t he and in Any there of femur xed to that the a humerus ball and fits socket into the of 1 of 1 trachea them bone bone; and open. where two moveable as in movement T ough attaches holds spongy made muscles bones joints a the brous muscle T ough skull, occurs. structure to a brous bone. one bone to structure another. bone: up of fine strands epiphysis (trabeculae) (head) found the mainly ends of space the than on scapula attachment view salts. joint process front are joints, no T endon that form the place Ligament to tissue rubbing keep meet; where tibia. head matrix calcium bula. tendons from to Joint and ● hard bone. bronchi ● Softer bone a and breaks also occurring with protein prevents ● terms planes. which in joints t he Bone ● and below. Key ● cartilage of with humerus in bone filled marrow compact fine strands bone bone-secreting shaft of the cell humerus 2 compact bone Haversian 2 system bone diaphysis (shaft) marrow: produces red and fine some white blood cell s lamella contains calcium canals central canal phosphate bone-secreting in there is forms a cartilage hinge over joint this with part the of the radius humerus and small pit cell (lacuna) that ulna 3 hyaline cartilage spongy bone p Figure from B.4.2.2 the upper A human humerus bone arm tough fibres (perichondrium) epiphysis spongy bone 3 tough, rubbery cartilage- matrix of secreting chondrin cartilage compact cell in pit bone yellow marrow p Figure are B.4.2.4 seen under Longitudinal the light section of the femur with drawings of tissues as they microscope shaft p Figure of the B.4.2.3 humerus A section and part of of the the head shaft 159 835292 CSEC HSB Unit B Topic 4.indd 159 08/01/2015 16:09 Bones, cartilage and Study ✔ The term and to The joints Tr y tip bone refers to a consists matrix of cells bones, by such organs of as the they yourself salts. by a bres Individual humerus, contain bones tissue collagen calcium as Bone surrounded composed hardened are organs. system tissue Bendy many this skeletal The main mineral compound of substance calcium and in bones is phosphate called with the hydroxyapatite. chemical It is formula a complex (PO Ca 10 Vinegar is a 4– 8 cleaner contains per cent the acetic alkali acid sodium solution hydroxide with and a pH has of a about pH of 2.5. ) 4 (OH) 6 . 2 Oven 10 –14. bone Requirements tissue, blood surrounded and by nerves and connective are tissue. 4 ● similar-sized removed ● 3 ● vinegar, [the containers cooked upper large chicken leg bones enough to bones with (femurs) cover all are the muscle good chicken for and this bones other tissues task] in liquid 3 a 10 per cent solution of oven cleaner (dissolve 10 cm oven 3 cleaner ● paper ● cling 1 T est the 2 tops 3–4 alkali there is 2– 3 dry could bone of of by each and the the tap water bones trying of the water. to Keep by trying scratch three to your containers one containers no the of with the bend twist fingernail on and vinegar, bones cling and wrap add its leave in test surface. somewhere and them; diluted dry. a safe place ● Are smaller ● Does the and difference, then leave Wash them thoroughly in tap of not the bones soaked in acid, water soaked. the bones in their respective solutions days. and this of after” photographs investigation of bones pH bones. hardness was length results? the towels. that extend the remove paper bone “before the carefully with flexibility more some Does each tap days, and with Y ou water) days. the T ake a or and for of into Compare If ● the 3–4 water 6 of bone cleaner After 5 flexibility one Cover 4 tap wrap the oven for 90 cm hardness Put 3 in towels time the affected the liquids to nd bones sooner have of are the bones answers left than to larger any effect meet. They to soak on and the record your following have any results. questions: effect on bones? the results? Joints Joints t hree occur Group No t he wherever 1: Immovable movement bones Group This 2: of bones Group 3: can be divided into joints t hese of joints. t he Examples are t he suture lines between skull. moveable at are knee, at allows adjacent Freely joints the xed cranium joint bones or occurs t he between between These of Slightly type joints hip, two groups. t he a small degree ver tebrae front of t he of of t he pelvic movement. ver tebral Examples column and are t he t he joint girdle. moveable also the called synovial knuckles and joints. between Examples the are centr um of the a joints thoracic at the ver tebra 160 835292 CSEC HSB Unit B Topic 4.indd 160 08/01/2015 16:09 The skeletal and the head adapted the system to bones of a allow are rib (see Figure friction-free would adaptations Bones, r ub against visible in B.4.1.8, page movement. each Figure other, B.4.2.5 If 157). Synovial movement causing and are pain was and joints not are like damage. summarised in hinge joint: movement this this in allows one cartilage freedom plane also These Table in and joints of the knee. humerus B.4.2.1. ligament frontal Pivot joint: The atlas. This gives odontoid peg of the axis fits into the synovial bone rotation of head and atlas; nodding membrane parietal of the head is result of the skull moving on the bone atlas – a hinge joint. atlas articulating canal for process spinal for cord skull synovial ball and fluid ulna cartilage socket joint: suture This temporal in bone any axis Immovable joint: Bones skull fused freedom plane. Also ligament: of movement seen in the hip joint. holds of articular the allows bone process together. odontoid to bone peg scapula q T able B.4.2.1 Summary of parts Part Function Cartilage Prevents and bone Ligament Holds Synovial membrane Produces bone Synovial uid Lubricates to functions from rubbing a synovial on bone; joint acts as a shock absorber bone synovial the of uid joint; nourishes the cartilage: cartilage prevents bones Synovial joints can be fur t her classied according to t he range rubbing of humerus synovial together movement t hey allow. A joint t hat only allows movement in one plane is membrane: synovial fluid: produces a hinge joint. There are hinge joints at t he knee and elbow. Ball and socket lubricates the synovial joints and allow movement in all t hree planes and t hey are located at t he fluid joint hip shoulder. ulna Lever Levers action are Wherever act as t he to Lever s t he of t here is move lever lever ways fulcr ums effor t or in in is t he is move t he load For by about t he which lever t he can and t he supplies in a body a t here of a wit h t here lever is load is pivots. load, a most lever efciency. action. Muscles which is Joints provide suppor ted a ligament t he by carpals muscle In joint each suppor t t he movement it. fulcr um load. and points movement of t he moveable t he body t he t he a moved ar rangement to – achieving levers. whic h joint radius what is means ar m, lot weight occur. of t he of held t hat to body. muscle in it biceps effor t t he The hand minimises is lif t t he The between a ar m provides small is t he t he t he load. acts t he load. effor t ver y a The needed fulcr um A as effor t, metacarpals and small gliding movement of t he end lever. biceps produces a muc h larger movement at t he hand flat This of t his Large, fast movements are t he result, e.g. a 25 mm t he end of of t he t he biceps results in a movement of 457 mm of The two therefore gives articulating slide flexibility over but one limited surfaces another are easily. strength. Also in movement the of joint: and t he hand at ankle. those Having parts are limited easily strength means that sprained. lever. p Figure B.4.2.5 human skeleton A range of joints in the 161 835292 CSEC HSB Unit B Topic 4.indd 161 08/01/2015 16:09 Bones, cartilage and The joints E F elbow E biceps L forearm held joint in The lever still or is action in moving Figure B.4.2.6 applies if t he hand is skeletal holding system somet hing upwards. muscle and weight Ligaments hand Ligaments are connective L In connective suggests, made tissue is of tissue, t he connective Ligaments attach connective made from matrix tissue bones tissue. cells t hat Like contains connects toget her. a tough tissues They bone make are car tilage, around collagen and t he and matrix organs t hemselves. bres. As its name toget her. connective tissue t hat F connects p Figure B.4.2.6 Lever action of the arm They var ying to hold Exam you bones that together muscles to confuse the ligaments and bones. tendons It is skull easy join the a attachment the bone the muscle end of The muscle move of to Insertion of point when xed when insertion muscle to your allowing on t he backbone Tendons hold They t herefore are to t he not “stretchiness” protein t hem gives some ligaments at is slip due to ligaments movement. t he out back of t he place. presence t heir You your of can head ability feel t hat t his hold and allow its nodding motion. muscle to bone and need to be ver y strong and non-elastic. transmit attach composed t he tension muscle to of collagen, developed bone t hat which by does is a muscles not ver y tough directly move. This to protein t he end of bone. t he origin. to the the does not contract; of bone muscle moves of page bres a ot her end is t he insertion and it is here t hat bone movement 166). does tissue so transmit at bot h tendon inser tions attachment that Collagen bres muscle. point the that (see The of and t hat its origins each force ends spread of t he a tendon like t he muscles. muscle to of out bre They ends are roots anchored of also on a a plant spread collagen ver y into rmly. t he The bone at out into t he muscle bre and can t herefore bone. contracts; The the This do terms The muscle elastin. The t hey two. occurs move ngers bit. t hat T endons is a of a sure to Tendons Origin stretch toget her, your making join able Key but quantities bones put joints, tip your Remember at tough, of if ✔ are bones when Achilles tendon t hat attaches a leg muscle to t he ankle is t he largest the tendon contracts. fairly in Summary The t he body. common of tissues of It spor ts the is prone injur y tissues t he of skeletal to tearing (Figure the skeletal system and a torn Achilles tendon is a B.4.2.8). are system summarised in Table B.4.2.2. 3 q T able B.4.2.2 types of Summary skeletal table showing the structure and functions of the different tissues 1 Tissue Structure Bone Hard matrix phosphate tough 2 of in calcium Properties Function Hard Protection and rigid Support which collagen bres Muscle are that embedded attachment levers are so formed for movement Cartilage T ough, but exible matrix Cushioning ends T endon T ough matrix collagen containing bres of T ough layer at bones and does Prevents bone rubbing on bone not stretch Connects bone to muscle transmit to force of contraction Ligament Skeletal muscle T ough but matrix containing bres and Made up muscle p Figure B.4.2.7 An X-ray of a knee slightly elastic of exible stretch a little Joins bone to bone Allows movement Allows movement at a joint bres many bres Can collagen containing Can contract Maintains posture joint contractile proteins 162 835292 CSEC HSB Unit B Topic 4.indd 162 08/01/2015 16:09 The skeletal Case only his Bones, cartilage and joints study Sanjay Sanjay system has was a an injury playing able to stand ankle so his Accident and playing football wit h friends when difculty called Emergency for football he fell and and hur t couldn’t help and Depar tment of his take any someone t he local ankle. to He weight take was t hrough him to t he hospital. The ankle is the area where the leg bones meet the foot. There are three joints at the ankle, the main one being between the talus (the ankle bone) and the tibia and bula. If you look at Figure B.4.1.9 on page 157 you can see the talus – it is the tarsal bone immediately underneath the leg bones. This joint is a hinge joint, which allows you to move your foot up and down. The side-to-side movement of the ankle occurs at the joint between the talus and the tarsal bone below it. There are many ligaments between the bones in the ankle, holding all of them together. You can p Figure B.4.2.8 imaging feel the Achilles tendon at the back of your ankle; this attaches a leg (MRI) A magnetic scan of a resonance torn Achilles tendon muscle to the calcaneus, the heel bone that lies below and behind the talus. Ankles are fractures. becomes more of sprain or leg doctor and br uised. it on was when may with (see to metal prevent Cells clot t hat from new the is he had may be and two bad or car ankle of his t he a may t hree where and saw ankle, t he ankle. torn is when sprains and break well area one involve bones talus t he in at jumping t he and is t he a ankle from forced or bot h a against accident. The t hat t he ankle dramatically ankle it was doctor and doctor him for fracture and might swollen severe tr ying range now sent badly elicited when reduced so and/or then Bone of to the this of requires is xing plates a a aid of to X-ray. need an move movement suspected an mature, have bone two types to that and t hat This operation to position cast can and by a in splint itself. the These across Later, the this blood cells gap temporar y bone-forming original active process or repair cells. bridge bone are a bone form its in healing in broken. compact the the the to temporar y that bones ankle of divide returns cell the tissue lining ends form to the living tissue bone into and by putting broken car tilage par ts remodelled break a of happen ankle in repaired screws (osteocytes) the a his a to around ot her connective the between was t he movement. produce repair bones Any are fracture Injur y are toget her. pins, the t he Sanjay ’s broken B.4.2.9) between likely injuries ligaments ankle region. sprain. happen t here to have fractures Figure twisting t he t hat bones a t he An ankle examination compared t he Ankle On common when most may pressing conrmed pin or as t he and is and painful. examined noted Sanjay in This falling The pain occurs fractures bones injur y and bones fracture. height, t he A to swollen t he fracture may prone strength. even in The cells repair healthy, p undamaged bone. Osteoclasts constantly break down the matrix of Figure B.4.2.9 fractures bone like and osteocytes Sanjay’s, vigorously these and in constantly cells larger are secrete it. During doing their normal numbers than usual. the repair functions of but a fracture, more An X-ray showing the and the screws the fibula. into plate into be a in at cast A the the ends the surgeon tibia fibula. for of and The several tibia has (right) put two screwed leg will a now weeks 163 835292 CSEC HSB Unit B Topic 4.indd 163 08/01/2015 16:09 Bones, cartilage and The joints Sanjay had is in now take a about to stay cast 6 in and weeks hospital all to his to have friends an have operation signed it! on The his skeletal ankle. doctors system His say it leg will heal. Questions 1 What happens when t he muscle attached to t he Achilles tendon contracts? 2 Explain how t he str uctures at t he ankle provide for suppor t and movement. 3 Describe t he 4 Describe how 5 Explain why it is important to keep Sanjay’s leg in plaster for 6 weeks. distribution bone tissue of car tilage differs in from t he ankle region. car tilage. Questions 1 a List the functions 2 Make 3 Compare 4 Name 5 Make in 6 a Figure 3 Make write an bone body where cartilage is found. b State the compare the to of joint compare structure and and the of bone functions state one structure of tissue ligaments example and and of and each functions of cartilage. tendons. type. the joints shown B.4.2.5. shows state one outline with. of the characteristics B.4.2.8 the the to types table and of label the three in cartilage. table Figure and 7 a places of Find bones. a in picture of your the positions skeleton X-ray drawing Label found their an function the of the of an knee. upper X-ray Count your a Name the parts labelled 1, 2 each. diagram hand. on of of part of with the drawing. a of the hand the hand and names number of Identify the that draw of the joints the do the of types hand joint not position different in types in you and found in hand. 164 835292 CSEC HSB Unit B Topic 4.indd 164 08/01/2015 16:09 The skeletal B.4.3 system Function Function of skeletal muscle Learning By Different types of the are t hree types of muscle tissue. The rst is smoot h muscle, in t he walls of t he muscle outcomes gut and also in t he walls of ar ter ies and be of this able topic you to: which ● is skeletal muscle should There end of veins. describe the role of skeletal The muscle second is cardiac muscle, which for ms most of t he hear t. The t hird is ● skeletal muscle, which is attached to t he skeleton and br ings explain why locomotion is about important to humans movement. ● All t hree types contain contractile proteins t hat use ATP to provide identify the muscles energy t hey need muscle cells and to it move. is t his The movement shor tening t hat of we t hese call proteins muscle shor tens ● explain a muscle muscle tiss ue is ma de up of a large nu mb e r cells (fibre s ) s e pa ra te d by con n ec tive of tissue. tissue fo r ms t en do n s t hat a tt ac h As muscle muscle why muscles describe only contract and sh o r t en ; t hey c an n ot e x t en d we h ave seen t he eac h next cont ra c t io n . Th ey are fou n d in p air s to bon es. in posture work to bend and and lift discuss factors including Mu scle s t h emse lve s t h at are t his which adversely read y affect for moves pairs good ways diseases can triceps arm c ylin d r ical ● connective and upper how antagonistic proper muscle the limb explain ● Skelet al of contraction. ● Skeletal biceps t he the skeletal system. against ot her. These ot her pairs to of muscles move bones. contraction of consciously decide are antagonistic Unlike skeletal smoot h muscles is pairs muscle under our as t hey and work cardiac conscious against muscle, control. muscle, each e.g. t he biceps connective tissue We bone t his wit h The str ucture Figure our gut when and and to our contract skeletal muscle. We do not have to do hear t. appearance of skeletal muscle tissue is shown in B.4.3.1. tendon T witch bres bundle There are mainly at use least fatty t wo t ype s a c ids as of skelet al t he ir so urc e mu scle of fibre. en ergy S low and, twit c h sin c e t h ey of have of lipid, t heir source fati g ue of slowly. en e rg y an d, Fast tw it c h b eca us e fib res t h ey lac k ma inly an u se en ergy gluc ose store, fibres a single store muscle fib res muscle fibre as fatig ue light band dark band quic kly. It has in been at hletes more in found who t hat do at hletes slow distance who do twitch muscle r unning; sprint bres while t he develop fast more twitch extensively type nuclei develop partially training. permeable membrane The importance of locomotion p Figure B.4.3.1 skeletal Many and human whic h means upr ight. can activities swimming be hands. muc h Our used many t hat hind for Having g reater impor tant are we our involve a few walk limbs many of two used activities, free over our locomotion: examples. on are hands control aspect precise just suc h to our hands limbs for not as make t he have four. locomotion, and use opposable cycling habit, bipedal allows while tools t han r unning, a This manipulating environment is walking, Humans our allows t humbs to front objects ot her us us of stand our have animals. whic h structure limbs wit h to The muscle An allow movements. 165 835292 CSEC HSB Unit B Topic 4.indd 165 08/01/2015 16:09 Function of skeletal The muscle Movement two at scapula Figure tendons the B.4.3.2 the system forearm shows t he arrangement of bones, muscles and tendons t hat origin, move hence of skeletal t he forearm. The humer us is t he bone of t he upper arm; t he radius biceps and of three ulna hinge biceps are t he bones antagonistic joint at of muscles t he t he forearm. t hat move The t he biceps forearm and up t he and triceps down are about a pair t he elbow. origins, hence The biceps has two points of origin on t he scapula and one point of triceps humerus inser tion where points origin: t he tendon joins it to t he radius. The triceps has one t he scapula. t hree triceps of two on t he humer us and on Its point of radius inser tion tendon is on t he olecranon Figure B.4.3.2 shows biceps muscle contracts t he triceps relaxes process forearm at of t he right ulna. angles to t he upper arm. The (insertion) to move t he forearm upwards (Figure B.4.3.3a). The well t he olecranon process ulna arm p Figure of the B.4.3.2 Antagonistic would Muscles each The Antagonistic muscles the other. other muscles that “work When relaxes movement to triceps of contracts original bring a The pair against” one across A contract about in t he t he same If t he position as triceps shown contracted in Figure as t hen B.4.3.2. contract; needs an pulling relaxes so t hey cannot antagonist. it is on t he pulled To lengt hen return to ulna to lower back to its its t hemselves. original t he forearm original This is position, lengt h (Figure and is why t he B.4.3.3b). now ready Exam tip or is t he triceps. pairs antagonist Af ter condition t he if t hroughout work triceps relax, they is of triceps t he t he against t he eit her raising Think of muscles, contract again. t he has biceps body. biceps and t he contracted contracts These to pairs it biceps can stretch are is only it. t he antagonist return Muscles antagonistic to are pairs its arranged because t he joint. t he Muscles only contracts, biceps muscles ✔ in happens. term to each can muscle triceps of stay t his muscles arm Key while or ot her such lowering places as each extensor in in t he ot her. of t he t he t he The biceps forearm. is The t he exor muscles of t he have forearm opposite and effects forearm. body were t here are pairs of antagonistic ngers. do a not ‘tighten’ or ‘loosen’. tendon biceps (contracted) origin radius triceps (relaxed) humerus insertion ulna b tendon biceps (relaxed) origin triceps radius (contracted) humerus insertion ulna u Figure (b) B.4.3.3 extension of (a) Flexion the of the forearm, forearm 166 835292 CSEC HSB Unit B Topic 4.indd 166 08/01/2015 16:09 The skeletal Muscle How for long ver y system Function you long can hold because your t he arms muscles above get your head? fatigued. You Skeletal cannot muscles hold can t hem Exam ✔ because ner ve cells r un out of t he chemical messenger t hey t hemselves stimulate may r un muscles out of (see page energy and 217). so be Alternatively, unable to t he muscles respond to ner vous opposite as The of skeletal healt h such body as t he weight, bending the and muscular exercise, and muscular posture and systems and how is we skeletal affected carr y by out is will just one in meet Hormones effects word mean affect you antagonistic. the that contraction where antagonistic. stimulation. Factors tip wit h topic diet, muscle stop Muscle as skeletal fatigue contracting which of the are term have described sure correct “working that also Make the you context use to against”. systems factors, daily such tasks lif ting. Diet Protein is needed to make t he collagen bres in t he matrix of bone tissue; Study ✔ calcium D is to and phosphate stimulate deposition by in and calcium t he are required uptake osteocytes vitamin in D of harden calcium bone. are to from People putting matrix. t he who gut have t hemselves The and a at of t hat of is Vitamin its decient osteoporosis in D acts because it the to body life (see below). People who consume more body increases energy t han t hey fat. This adds weight to t he and t he strain on joints. People developing who are over weight and obese are increasing another cells hormone in in the one the part blood intestine of and and in the bone. See Unit B.6.4 to muscles see and a from require cells store as travels stimulates later tip vitamin stimulate diet risk role t he risk the features of hormones. of ar t hritis. Exercise There to are many muscles especially several and benets bones more new more exible mineral tissue as matter of e.g. exercise, more extreme benets, grow is forms. more If a but to and become secrete become larger, more also some happen person capillaries t hey to likely risks when exercises develop muscle synovial inside tone uid because people regularly muscles, improves, and bone damage take exercise, t here t he joints lays are muscles become down more stronger. Key No muscle are always is ever totally relaxed. Wit hin ever y muscle, some muscle bres Muscle contracted and t his low level state of contraction gives terms tone contraction muscle its tone. The advantages of t his are t hat muscles are maintained permanently active state and so are capable of rapid contraction and t he body is kept upright and t he internal organs are partial muscle that helps to posture. when Posture required of in maintain a The t he kept The position of the body, in e.g. in a good standing posture or position. a slouching posture. Posture Your and posture bad posture is the standing if t he column t he joints knee In t his to maintain Bad ● more t he to in of Figure balanced balanced your on on straightened t he muscles position leads energy leading is is are position posture postures head ver tebral positions of of its You B.4.3.4. t he can We see have a examples good top of t he point of attachment and t he t he body. t he body feet are are ver tebral using as t he on little good standing column, to squarely of t he pelvic t he girdle, ground. energy as possible body. to: being fatigue needed and by t he muscles to keep t he body upright, backache 167 835292 CSEC HSB Unit B Topic 4.indd 167 08/01/2015 16:09 Function of skeletal The muscle Good ● Bad ● ● t he digestive less efciently t he breat hing less efciently t he main less blood. Prolonged feet. bad better Ligaments normal t hem of pain type t he of of The Figure B.4.3.4 Examples of bad and posture ● in a deformed down. and upright posture. When positions. Poor posture leads overstretched too of column on ligaments t he result carr ying a and rm at chair is slouching. suppor t t he working t herefore ver tebral Sitting t hey an and causing injur y or much strain on lif ting (poor lif ting an bones to of Back accident e.g. by pain are t heir spine, ligaments pain. ligaments, maintain t he on and likely wearing keeping one to side neck be t he t he wrong lifting to discs are wit hstand (tension). follows Keep (see par ticularly being technique) at risk squashed from can damage damage (compression) t he back. because more t hey t han To prevent damage, a good lif ting technique being can prevent should t he ● Keep ● Use t he be Always People Incorrect ways The to correct lift heavy as straight as you to stretching lif ted object legs bend by and as t he hips from t he close to you as possible so as to reduce t he object. to help knees suppor t as t his t he allows lif ted t he weight. legs to suppor t t he injuries involved in spor ts inevitably r un t he risk of injuries, most of which lifting position B.4.3.5 column weight. Sports lifting B.4.3.5). ver tebral exer ted your lif ted position Figure discs. leverage incorrect role compressed exibility, during evolved t he Figure not t han t herefore posture ● p major to and working good as Correct body being putting stretched and a and inter ver tebral have p t he lead sitting t herefore system shoes. Bending Poor are may and compressed becoming includes correct spine t hat result play lengt h in your for compressed being vessels posture also being system blood Posture much system skeletal and objects may involve Pulled or bones, torn hamstring or muscles, muscles: calf t he muscles. tendons muscle To treat or car tilage. bres t his come as a apar t. rst This aider, is likely follow t he in t he RICE treatment: Rest à Then Ice seek Tendon t he will Torn t he (see help. t his to of in will Elevation time t he most re-join t his à t he tear torn and t he If a require ends. of Paris an takes treatment happens complete two plaster muscle t he commonly B.4.2.8). immobilised car tilage: The extent Figure needed tendon ● on r upture: heel be Compression medical depending ● à heal will to t he Achilles r upture has occurred, This for to is followed about operation 6 var y given. by tendon in surger y having t he weeks. using keyhole surger y. 168 835292 CSEC HSB Unit B Topic 4.indd 168 08/01/2015 16:09 The ● skeletal system Tendonitis: wit h t he of ten cure ● a muscles result t hat happens to t his as Dislocation: forced ● to ligaments and in or limb fracture may have – is for moving t he bone – a person, as is age. chiey results tissue. generally t he There t hrough t he reduced secretion of women tendons rest. is needed Rest This to a joint difcult are and torn t he Treatment as area a result becomes usually involves more bone t he back weaker may of bones immediately in once be place. t hey at see joint are doctor or Dislocations have performed a a to been p shor ten Figure collar t he B.4.3.6 X-ray of a fractured bone fracture. ulna; Fractures tibia and are most bula). likely Fractures to are t he t he overlying bone come skin surface t hrough t he is intact overlying is t he away common wearing t he case Anot her given of in D to car tilage pain, ar t hritis result joints, of of is also caused ot her in t he in a bone. This for ambulance wait all for t he injuries, diet e.g. a in diseases, a a lack by itself immediately, making t he course of t he An t he of joints for D t he body’s in diseases and pain of is not person This and of as to For in bone, in t he absorb and t his t he reason, synt hetic HRT. affect t he joints. osteoar t hritis leads of to to which system t he matrix) type inability old protein involving or in material on needed t hat t his ar t hritis, defence stress women. known joint. organic bone t herapy example hip of treatment is especially of deciency post-menopausal discomfor t resulting heal ambulance. (vitamin needed number at t he usually and amount people, replacement a will limb bone in rheumatoid t he an broken including older people. below). t he in car tilage study has system causes follow wit h is car tilage of t hey reduction hormone older t he phosphate ot her form This to t he sending oestrogen t he away each a several and as in in common vitamin name of bone lung while inactivity choose Wearing a crack from of Ar t hritis t he a but skeletal are of known cause. or t he and fractured most calcium oestrogen, (see t he at features: involves the deciency use – possible Osteoporosis against called immobilising of t he on even recurrence. ends slight fractures comfor table ver y around must surger y broken broken Diseases is is penetrated rested. many put (radius cer tain fracture fracture a one become fur t her bone to – if and put surface stress diet, is hur t, t hrowers. accumulate. person cases, bones fracture compound bone and javelin becomes uid will ligaments stop according open It and ligaments when The who serious broken t he closed it strain muscle injuries First-aid as as In rib ● occurs recur skin used, inamed skeletal joint. position. stretched. cracked ● t his of t he tissue t he tend Bone ● out of paramedic named players Movement and trained occur constantly become when wrench. blood immobilisation A tennis occurs sudden swollen ● are t hey of t his. Sprain: of if Function ar t hritis bones move has a and is r ubbing ver y much different mistakenly attacking stiffness. 169 835292 CSEC HSB Unit B Topic 4.indd 169 08/01/2015 16:09 Function of skeletal The muscle Between the car tilage (known may be causes Foot The feet bones result ver tebrae pressing of on A the in the slipped backbone disc nearest occurs spinal ner ve discs of tough centre of a are the (see Unit disc B.6). This pain. of t he t he of feet are weight of ill-tting linked t he to body. footwear, car tilage Many bot h in to form problems a exible arch, associated childhood and wit h adult hood. children bones permanently shoes ● hammer a babies ● so deal suppor ts children’s can ● great adjacent brocar tilage). system care are Young As a of as displaced, many which centra skeletal should for contain damage go young feet should be will spread t he a lot t heir barefoot children measured of exible feet. to The allow should when car tilage, r ules rapid, allow t he to be unrestrained plenty child tightly is of tting followed room standing foot for so shoes are: growt h feet t hat to its grow weight toe T eenagers and feet out. adults corns A number by poor of problems posture due to can be high caused heels, by ill-tting which t hrow shoes. t he Backache foot for wards is in caused t he bunion shoe (see against t he base heeled p Figure B.4.3.7 ill-fitting Problems caused by above). r ub of t he t he shoes. is when it to t he bend big toe These big so Corns inside toe t hat are of t he by cause pushed end painful shoes. caused can is hard, t he wearing t he bones inwards points patches Bunions are of narrow, to and skin painful, caused pointed become cr ushes toes joints shoes deformed. t he when swollen or at high- Hammer adjacent toe, toe causing downwards shoes (see Figure Case B.4.3.7). study Novlette ’s Novlette She has down has just been she pain regular rest t hat several and she and has and always t hought not someone The she consultant was femur. wear and will a (DDH) for knee. painkillers, examination her returned her does at hip young As and t his t he tear is from complaining towards which her new of The a affecting need t hat t hese in hip are her t hat of as in her lef t activity, t, but sleep. longer pelvic or t hopedic wit h to is She working. radiograph, Novlette surger y was is consultant. hip r unning such now was r unning, giving a t horough consultant hip for tells dysplasia shocked only as also using Af ter t he developmental replacement. as old she people, mid-30s. t hat t he her does car tilage not for hip socket of responsible no a an pain keep ability known femur t he to replacement t heir tells and a hip to star ted week her inspection condition visit pain times but a worsening t her snuggly has t he joint in led to did not pelvis into is t he severe form too properly shallow pelvis t he when for t he constant osteoar t hritis in t he hip pain. 170 835292 CSEC HSB Unit B Topic 4.indd 170 08/01/2015 16:09 The skeletal Novlette remove side of is told t he t he socket wit h system in leg t hat existing hip, t he special t he will be will re-set You for can be will by see t he par t t he equipment. replacement socket. during worn-out upper pelvis polyet hylene) hip Function operation hip of head A false t he made an be will will removed be and plastic (high girdle. The of joint t he in end femur Figure on hollowed of hollow of t he t he density of t he femur. into t he The new B.4.3.8. Socket out A hip replacement is an example of a prost hesis – an ar ticial in and pelvis plastic as replaces in Novlette’s now The many latest arms by arm. into if t he a t hat real prost hetic a in failure par ts involve t hem to t he are arms to Ot her and to injur y, develop available t hat for people ner vous muscles able arm. by giving t heir chest control People was by damaged prost hetic muscles ner ves it body developments muscles. as t he condition, different into The chest of connecting inser ted just par t t he operate control arm t he to of by are t he are prost hetic to about inser ting ner vous 2 t hese it sensors system. Stem These developments gives people much greater control and of and Novelette’s have to fur t her and hip years, hip life spend 6 3 if it to is no out, her of benets alteration in in t he long term. t he operation All mechanical a They new one surgeon. far usually require condition. will and af ter may her shor t- of r unning. different. she and and out independence. cr utches going removed bot h more change, on are wear getting long-term temporar y to wit hout does and much mont hs replacement t he going replacements but weight but is mont hs under taking on t herefore put She The outweigh in, is last which worried She t hen devices is a What sor t of joint is a wear, t he 3 signicant putting t hat’s inconvenience of tr ue, t his activity. t he hip What is 3 What are a of inserted joint? liner 2 part will where about says hollow femur Head 1 replacement into 15–20 surger y consultant t he and will revision hip sensor y inserted awareness place prost hetic t hinking t he into or, surger y. connected involve to There Electrodes are limb t hese disease, replacement signals developments connecting properly. systems. send in accident, hollowed liner device cemented t hat muscle out stem t he ball skeletal completely incision pelvic t he head hip surgeon will femur t he into new ar ticial t he Through femur t he into inser ted tting an t he of socket cemented be joint. of in femur into plastic pelvis prost hesis? t he long-term benets of hip replacement surger y? 4 Questions p 1 State the three different types of muscle tissue and their roles in the Figure B.4.3.8 A hip replacement A radiologist body. operation 2 The biceps contracts arm the of 3 when triceps other the biceps muscle and the triceps the a What type b What waste of and c What work vice contracts? contracts? is muscles relaxes b sort antagonistically, versa. What of a will muscle What will happen is the i.e. when happen to the triceps? arm d one to the when What sort biceps? respiration product begins to accumulates be in used during muscles strenuous during exercise? strenuous p exercise? c Suggest why pain (cramp) is associated with muscle Figure X-ray d What type of muscle does not B.4.3.9 checks an fatigue. of a hip replacement. With more fatigue? people are living longer becoming more hip replacements common 171 835292 CSEC HSB Unit B Topic 4.indd 171 08/01/2015 16:09 Function of skeletal Talk The muscle 4 Explain what is meant 5 State four 6 State three 7 Explain the skeletal system. by muscle skeletal system tone. about ? You can never have too characteristics of good posture. many problems caused by ill-fitting shoes. shoes Jazmyne buy says another shoes. Her she pair be bad putting for her of brother physiotherapist her is back at is they How would that her and risk she in is be that bad you diet for the long-term health of the the The skeleton performs the following functions: support, movement, convince brother consumerism for poor Summary is can breathing and production of blood cells in the bone marrow. right ● and a a protection, Jazmyne of will ● future. consequences to high-heeled who says health going The skeleton provides solid structures for the attachment of muscles and often ligaments health? ● and cells secrete that cartilage rubbing that are A long filled a of ends a marrow. as relate in of at the ends joints that allow the of of bone, bone bone skeleton. them. is of struts of running Both matrix preventing much consists vessels The harder with bones as many closely through contain secreted it spaces packed a tiny or a femur has a variety of structural upper end that fits into a socket allowing free planes bone that of less resists compact likely composed Ligaments is a e.g. between to stresses bone break in all directions surrounding right across bone marrow compared with at a between synovial the as so two bones joints, that shoulder of the forearm and lower leg at these allowing fibres bones in the fibres as well meet. are Hinge allow hold in as No cranium. protect them joints, in between movement Some the bones from one movement by at the occurs is ball at fixed occurs Most movement fluid elbow three This fibres. synovial plane; in stretching. bones. movement backbone. e.g. together. withstand collagen lubricated movement hip to that movement vertebrae which allow bones ligaments collagen joints. and of movement. bones; elastic synovial joints to tough little bones ends between moveable known of where joints the knee) both contain place the or muscles stretch ligaments meet friction-free attach at are covering and are joints ends consists Compact made (elbow Both are bone blood of functions: spongy shaft T endons also the matrix humerus three structures cartilage wear occurs on tissues surrounds structures hinge joints, a its all hollow rounded joint is that The with to head made long solid A main Spongy tissue such that hollow ● other. salts. with rounded – why two matrix Cartilage each bony bone – – the large soft. movement – body. canal. features – is the are a calcium cylinders central bone against contains ● support Cartilage by ● that and and and are knee, socket planes. 172 835292 CSEC HSB Unit B Topic 4.indd 172 08/01/2015 16:09 The ● skeletal system Movement the and triceps The origin of that does not is at on this the triceps the scapula. move. lengthens insertion is are of of of the antagonist in (e.g. this the it) two triceps contraction humerus biceps (raising is the is on while pairs as the ulna. triceps) so it while the can contract one is muscle ready skeletal muscle arm. muscle and it it pulls relaxes. and When antagonistic of biceps the triceps on of of radius humerus they the upper contracts the an contraction end the the of the on is as in biceps (straightened) together The – When origin: extended found the by the scapula occurs. work themselves. its the forearm points triceps muscles lengthen on about alongside insertion the forearm and is The three The brought lie movement flexing has is which biceps that the biceps Skeletal not the radius, The The forearm muscles, end contracts ● of Function one the on triceps biceps relaxes. pair of and shorten (e.g. to contract by skeletal muscles. but biceps) when required. ● Muscle This ● is tone Humans ● has Various lead to to general the health bipedal objects led to factors – the low of level walk given adversely on us affect being contraction tissue two the ability control the and discomfort feet leading especially or to hands and use poor exercise. free tools diet increases strain on back. and our muscle. by to and so environment. system: the bunions promoted make the obese puts in is Having of skeletal posture corns, and legs. overweight Bad to of muscle sophisticated osteoarthritis. pain damage we has our osteoporosis; developing lead the for are manipulate doing is good may the ligaments Poor hammer risks and footwear of may may toes. 173 835292 CSEC HSB Unit B Topic 4.indd 173 08/01/2015 16:09 Practice The Questions Practice c Describe d What t he is a joint 2 3 as it bone. relates to [3] t he human [1] A e 1 of system Questions skeleton? Section str ucture skeletal Which of A It is striped B It is also C It tires D It is Which t he following as easily t han in of following dislocation B sprain C bunions D tendonitis of t he not tr ue tubular following types like caused reflects skeletal t he muscle? Feet B Knees squarely are C Head D Ver tebral planted slightly balanced bent on column on top and t he bad of t he by of t he type of motion joint shown possible. below and describe [3] muscle. large intestine. ill-fitting shoes? posture? The diagram shows a joint. ground. instead pelvic of type microscope. 2 A t he t he muscle. ot her organs is of under voluntar y found t he is appearance known more A Which in Identify of a Identify b Describe t he str uctures labelled P and Q. [2] straight. ver tebral girdle t he functions of P and Q. [3] column. aligned. P Section 1 The B human made up of a Identify b State body contains bones t he four and bones a skeletal system which is joints. labelled functions of t he W, X, Y skeleton and Z. system. [4] [4] Q c i) Name t he diagram ii) Explain move W d Identify how t he t hree ligaments. muscles below. t he lower labelled A and B in t he [2] muscles arm. differences you have labelled [5] between tendons and [3] X A B Y Z 174 835292 CSEC HSB Unit B Topic 4.indd 174 08/01/2015 16:09 Unit B Homeostasis B.5 B.5.1 Many Excretion chemical potentially discussed reactions harmful in Learning Unit go on inside substances, B.1.3. Our such cells your as body. Some hydrogen contain the of these peroxide, enzyme which catalase By produce that the should we hydrogen peroxide produced by our metabolism into water be and it has any chance to do harm. Ammonia is another ver y this topic you to: state the names of the oxygen waste before of able conver ts ● any end outcomes products of human harmful, metabolism or toxic, substance that we produce and this also needs to be conver ted ● into something less harmful as soon as it is produced. We conver t it explain the excretion urea, but unlike oxygen and water we cannot do anything with urea so it of the from body. the body They also in urine. help to The kidneys control the are water the in main the excretor y much we get rid of it in the urine and if we do not body have so if we enough can retain some. The other excretor y organs are the lungs humans the roles organs involved of in the excretion have then and describe the urinary describe the structure system the ● kidneys in explain organs ● too of is ● excreted importance into of the the kidney. liver. The Major The skin metabolic is poisonous) The of Carbon is t he ions to metabolic substances dened excretor y mineral as in t he waste we t he substances (see Figure B.5.1.2). t he t housands waste produce body t hat elimination products of are from are par t from of body metabolism our of toxic and of metabolism. (or substances in products are carbon dioxide, urea, bile pigments, salts. dioxide dioxide produced into excretor y requirements. and Carbon best some reactions substances, human water of waste chemical Excretion excess removes sources different It also product lungs where from t he when breat he of aerobic mitochondria Carbon diffusing we t he inside blood. t he is dioxide it blood out is and t he t he it t hen transpor ted conver ted into (see is respiration back alveoli. comparison diffuses as into We (see Unit from hydrogen carbon excrete between B.2). cells carbonate dioxide carbon inhaled before dioxide and exhaled p air in t he practical activity on page Urea Excess amino acids reactions known toxic it and are as would broken down deamination. be fatal if we in We let Figure B.5.1.1 carries human One the A hospital technician 100). it t he liver cannot into ammonia by excrete ammonia as circulate in t he blood before of organs most transplant. common operations involves the main body’s for transplant kidneys excretory that are organs chemical it is ver y leaving Key terms ! via t he cells, kidneys. Ammonia decreasing t he would activity of increases enzymes t he (see pH page in t he 73). To cytoplasm prevent of Metabolic t his chemical happening, liver cells react ammonia wit h carbon dioxide to make carbon which blood is much above a less toxic, cer tain but still harmful concentration. if allowed to accumulate waste reactions Products in cells, of such as urea, in dioxide and urea. t he Excretion The the toxic body waste and of products substances removal from materials, of in metabolism excess of requirements. 175 835292 CSEC HSB Unit B Topic 5.indd 175 08/01/2015 16:10 Homeostasis Excretion Bile pigments skin excretes urea Bile and pigments are made from t he haemoglobin molecules in worn-out salts red blood cells t hat have been broken down in t he liver. Most of t he bile lungs pigments excrete are excreted in bile, which passes from t he gall bladder into t he carbon small dioxide in intestine t he skin, (see page causing it to 79). go If t hey yellow are – a not excreted condition t hen known t hey as accumulate jaundice. liver processes materials makes toxic and Water them harmless Water t hat is a metabolic occurs in product almost all as it of t he cells is a waste body. product Water of aerobic produced respiration from respiration kidneys is excrete and known as t heir have p Figure B.5.1.2 Human excretory as diet more writing on an answer to a remember dioxide salts Mineral salts or ions many of These are and products word equation question are ions we in need water and ions for to show such as, we t he we in animals This does need, in lungs lose any t he rely not t he in and t he on it apply excess diet We some urine chemical diet. our sodium, is remove almost is to us entirely and excreted. if we Some lost (see day, in control so any in Unit reactions cannot each is sweat, is but B.5.3). t he body. exactly excess are These how excreted. removed potassium, t hrough t he phosphate lungs and and calcium breat hed out in ions. to urea, water, salts and bile pigments in exhaled urine. Sweat are made by ltering t he t hat body blood (see B.5.5) and so inevitably contains any include t he does not want, which explains why water, salts aerobic where urea are passed out of t he body in t his way. cannot rely on It is arguable whet her t his they really excretion because you sweating as a way of excreting from. whereas Building a Create table in kidneys Study a sources, this book. B.2, the need is process. It that to help a is very one keep environment is important of the our processes so to Y our in look table better this summarise they excretion removal release of the are information produced, mentioned of bile carbon from in and this dioxide the gall about how excretory we chapter from bladder excrete are the and substances, them. described body its is role Many described in of elsewhere in digestion Unit at function about things this B.1 these and sweat pages formation when is compiling described your in Unit B.5.5. is Y ou table. that could have the following headings, but you may think of ones. cells Source Site of production Method of efciently. in the body excretion concept Carbon of time. life internal constant can more “keeping to The substance There t he Activity where of Excretory body all tip described Excretion work table methods Unit rest much body dioxide the of in produced t he kidneys The their the how not Written in deser t food. t han evaporation air. waste, ✔ body Carbon is come Some dr y that and respiration by enter t hese substances the t he control Mineral is excretory in ver y tip excretion, carbon lost kidneys salts In water. of organs t he Exam consists water inevitably ✔ metabolic urea salts constant” in dioxide the Unit. 176 835292 CSEC HSB Unit B Topic 5.indd 176 08/01/2015 16:10 Homeostasis The Excretion urinary system inferior The kidneys are paired organs which form par t vena cava of aorta: carries t he urinar y system. Figure B.5.1.3 shows t he oxygenated blood back to to t he in t he urinar y system and t heir the relation renal artery: blood from vein: ions and small molecules, such blood as from and glucose, are removed from t he of t hese leaves t he are returned kidneys. to t he However, blood any or are sur plus to t he body’s t he of urine. bladder, The urine where it is passes are needs from stored. t he When left full, t he urine is passed out of t he kidney kidney not carries urine become kidneys t he to kidney to bladder bladder: bladder as is the before t hat from par t inferior cava ureter: needed to the the blood. vena it to the carries aorta kidneys, kidney Most carries kidneys. t he water heart heart renal In blood the from str uctures carries deoxygenated ot her body it expands stores urine during sphincter muscle contracts to urination. urethra: urine urine in carries keep bladder during but urination Kidney structure relaxes during urination You This can takes shape kidney. The it is blood pyramids t he from shows because fewer t he shows urine B.5.1.5 a see also a t he view outer full of a a kidney which kidney of a region t han region to is t he at cor tex, cortex: are where filtered where the top The blood of are which Urine t he has a medulla ows ureter B.5.1.3 The human urinary system dark is down called red pink small t he colour because tubes it in has t he pelvis. and returned it Figure molecules blood before p Figure t hrough inner small from most B.5.1.4. “tube”t hat bladder. cor tex. t he Figure t he section vessels. t he in is t he ver tical blood vessels into of ureter leaves to kidney p Figure ureter renal blood vein: medulla: in kidney with A kidney cut a to vena the cava helps control content A carrying back inferior B.5.1.4 attached of of water renal blood artery carrying kidney blood from into aorta p Figure B.5.1.5 vertically pyramid: part in urine which of the medulla drains into pelvis: a region at to outer area), area) and show the medulla pelvis cortex (reddish open (brown inner (white) white the top ureter the p of pelvis Figure B.5.1.6 Compare this A diagram with Figure showing a the ureter vertical section carries urine kidney to through a from bladder kidney. B.5.1.5 177 835292 CSEC HSB Unit B Topic 5.indd 177 08/01/2015 16:10 Homeostasis Excretion Tr y Kidney this yourself dissection Requirements ● sheep ● sharp or 1 Examine a kidney See if you to a kidney Make a your kidney 3 Use a the 4 side 6 of the you and you kidney overall be see the may where with they of the position to that on Figure ureter have shape to still to are kidney B.5.1.4. attached. remove some attached and occupied is arrange by the it on right Make a drawing that a on show show are the very they would your drawing. cut should to vessels be. along the edge the line outer edge of the you of the on kidney. external dotted lines length kidney drew the and use Measure follow the shape short, on the Do of the the side opposite not cut all kidney. to see some On the into white each which through Figure kidney where make be tissue, the blood scale able pink in of and This kidney. those and to the should cutting what vessels them; similar show hilum. now Keep a the the areas in drawing of the to knife ridge of the drawing through there pelvis 5 your identify part ureter include the should is blood cutting body. the sharp and Note it Compare have The drawing way Y ou the kidney. still find that and of towels hilum. If opposite side for paper labelled features. on board ● may so in ● them. the board kidney scalpel can find called or whole The fat 2 goat knife tissue side partly kidney the of slit visible. the slit obscures so that that you have This white you the you should cut. At tissue be able the far is the to see a pelvis. cut it into two halves like B.5.1.5. to are show the brown, shape red and of the white. two cut These surfaces are the and cortex, indicate medulla pelvis. Questions Talk about ? Y ou have Why do when you you Discuss family one brain have can this and two live with your and 1 State five 2 State the 3 Name 4 What substances that are excreted. heart. two main roles of the kidney. kidneys with your one only one? friends, teachers. the 5 Is the is the body the your parts of role where removal the of sphincter there of human are faeces urinary system muscles sphincter from our in the and state body? the function Name three of each. places in muscles. gut an example of excretion? Explain answer. 178 835292 CSEC HSB Unit B Topic 5.indd 178 08/01/2015 16:10 Homeostasis B.5.2 The The functions of the kidney Learning By Kidney the end functions of t he kidneys are summarised in Table B.5.2.1. Note t hat have functions ot her t han excretion. You only need to be be t he T able rst two B.5.2.1 functions Summary How Excretion Urea and of kidney certain alcohol, wastes relate functions are other drugs removed Osmoregulation Surplus water Controls Surplus hydrogen pH incorporated organ Releases bone Kidney state is waste and substances other from the removed toxins blood from the are and including passed blood those metabolised; and out in made these the in the kidney is in B.5.2.1 a long long a into urine incorporated into ● urine ions are neutralised or removed from the blood and urine hormone about t hese shows tube, loop, wit h t he t he that one increases million nephrons t he two loop Bowman’s glomer ulus. which The passes where in of the the nephron the production of red blood cells selective describe ultrafiltration selective reabsorption describe the in and composition urine. the t hat microscopic blood is tubules ltered and called urine is Did str ucture of an individual nephron. It is coiled of regions. Henle. One In end between of t he t he two nephron a capsule, enclosing a knot of blood ot her end leads into a wider tube, length is down into t he of an about adult human 12 centimetres par ts about the size of a computer cup-like capillaries called know? composed coiled has you ? formed. t he The human kidneys make called litres of ltrate every day and urine. The collecting produce duct, a functions occur of 170 t he their reabsorption mouse. shape, structures to and long, a of (nephron) ultrafiltration kidney is structure (nephrons) contains It the body excretory The of you marrow tubules nephrons. Figure topic to: tubule the kidney ● the blood Each this achieved when Endocrine of able described. ● Function of outcomes describe ● q kidney familiar kidney wit h the t he ● kidneys of functions should The functions 1 to 2 litres of pyramid. rest of the ltrate is reabsorbed. glomerulus branch of renal artery Bowman’s capsule distal convoluted tubule branch of renal vein loop proximal convoluted tubule capillaries filtration collecting duct Did you know? ? Y ou were nephrons p Figure B.5.2.1 A single kidney tubule we you examine a prepared slide of microscope you will not see t he a section t hrough a kidney The reason is t hat nephrons a million kidney. whole of one nephron as are t hree dimensional to have with The far age, more of but them under clearly we str uctures need as people with one as kidney t his. with each decreases seem than a in (nephron) number If born live a healthy life. t hat 179 835292 CSEC HSB Unit B Topic 5.indd 179 08/01/2015 16:10 The functions of the Homeostasis kidney medulla cortex have regions t hat are highly coiled so t hey never lie in one medulla plane. Imagine taking a cross section of a bowl of spaghetti; pelvis how renal brings to would the blood spaghetti from scientists did Figure Figure renal vein: takes blood out ver tical away from wit h t he arrangement of one piece of t he sections? kidney to Not easy, derive but t he t his is diagram what you see B.5.2.1. B.5.2.2 kidney. kidney shows Remember has about t he position when one you of look million t he at nephrons Figure nephrons inside B.5.2.2 inside t hat a each it. kidney ureter collecting work kidney in the you artery: Figure B.5.2.3 is a photomicrograph of a section through cortex the cortex. You can clearly see cross sections through three duct one kidney glomeruli. Each glomerulus is surrounded by a Bowman’s tubule capsule, which is the thin white circular space that you can see. p Figure B.5.2.2 Vertical through a of nephrons three kidney section showing on the the position Two main processes take place in t he nephrons. left ● Ultraltration Bowman’s ● Selective of blood plasma from t he glomer ulus into t he capsule. reabsorption capillaries around t he from t he ltrate back into t he blood nephrons. Ultraltration Filtration is a process ultraltration t hat p Figure of the B.5.2.3 cortex glomeruli used molecules Figure B.5.2.4 under high or t hat separates when t he par ticles par ticles a kidney Bowman’s capsules shows how ultraltration This comes about glomer ulus t he glomer ulus, or has Like pores a larger creating all in a internal build-up capillaries, t he high cells efferent leaving blood the glomerulus: has than a the wider a blood network membrane through small molecules pass Figure vessel in t he t he is entering leaving glomer ular lining like functions t he t hat in by t he a have sleeve, like a glomer ular are t he This dark small cells t he is sieve. small a brous The capillaries enough lining t he membrane movement blue of (lumen) Bowman’s has molecules which here from of The capsule : and blood forces to go t hrough capillaries into and Bowman’s arrows of in molecules Figure is shown B.5.2.4. and the the that blood easily the glomerulus mixture B.5.2.4 glomerulus Ultrafiltration and Bowman’s in of substances t hat forms inside small ions are t he forced Bowman’s capsule is called t he ultraltrate. in main constituents of t his uid are water, form glucose, ultrafiltrate ions potassium), p t he capillaries, t hrough capsule. The can glomer ulus vessel vessel capsule : pores ions t he of capillaries diameter efferent Bowman’s in blood because inside inner term small, in “leaky” this pores t hen up t han make t hat inside substances t he builds The ver y vessel glomerulus vessel pressure Blood t he pressure t hat t he pressure glomerulus are t hem. membrane the occurs. because diameter of Around blood sizes. ions. pressure. t he holes blood different separated showing capillaries. afferent of being Photomicrograph of and is is (e.g. sodium, amino acids chloride and urea. and Red blood the cells and t hey are large molecules, such as proteins, remain in t he blood because capsule too large to pass Selective reabsorption Look at back Bowman’s the Figure capsule collecting most are t hrough B.5.2.1. could ducts reabsorbed to pores substances eventually leading into All t he the blood pass and that right pelvis. This capillaries t he are in along does from brous the the not various membrane. ultraltrate nephron in and the into happen because parts the of nephron. 180 835292 CSEC HSB Unit B Topic 5.indd 180 08/01/2015 16:10 Homeostasis First coiled Figure t he The shows glomer ulus how forms a t he efferent second blood capillar y vessel network taking around blood t he away rst Exam ✔ from The cells lining t his par t of t he tubule absorb substances ultraltrate and pass t hem back into t he bloodstream. rst Figure the from by ultraltrate diffusion, from by t he propor tion t he but in active ultraltrate. osmosis. of Table different t his way. transpor t Much B.5.2.1 of molecules Some is t he shows t hat substances required water how are in t he to t he normally pass across removal all of ultraltrate kidney is adapted is to tip coiled tubule proximal is also convoluted known tubule B.5.2.5 and t he kidney from as shows the coiled The t he of tubule B.5.2.1 tubule. functions the second coiled tubule is reabsorbed t he t he cells glucose known as the distal convoluted tubule. These parts of are coiled to reabsorbed as help substances t his possible pack to in the as reabsorb into the nephron many cells wanted blood. reabsor ption. q T able B.5.2.2 How the kidneys Feature Each are adapted Explanation kidney has over a million for of reabsorption. how this helps reabsorption Increases surface area for reabsorption Increases surface area for reabsorption tubules Tubules are long Tubules are coiled Cells lining microvilli Cells the on lining their the mitochondria Loop of Allows tubule inner tubule in have their surface have tubules Microvilli cell many lining the be reabsorption long the tubule Mitochondria cytoplasm to increase without produce by but surface active ATP , contained area of increasing which is within the a a small membrane its overall source of space of each size energy for transport Henle Bowman’s The loop of Henle works to increase the salt capsule glomerulus content of the tissues in the medulla. This 70% helps in the reabsorption of water from the of the water, some mineral acids are all salts the and glucose, amino reabsorbed ultraltrate in the second coiled tubules and collecting ducts. You are not expected to be familiar with the complex processes involved. Second The coiled second tubule coiled and tubule collecting and duct collecting microvilli: duct are also surrounded by a network of increase surface membrane capillaries. The cells lining t hese par ts of increasing tubule and can pass absorb t hem ions into t he from t he blood area of capillary without network t he size of cell ultraltrate capillaries. Cells lining the second coiled tubule absorb mitochondrion: mineral salts from the ultraltrate and pass ATP for provides reabsorption them back into the capillar y. However, the major function of the second coiled tubule and collecting duct is to reabsorb water. surface membrane outside of on tubule The volume of water reabsorbed by the second coiled tubules and collecting ducts p Figure B.5.2.5 The upper part of a single nephron with a high-power depends on the how much water there is view of the cells that line the first coiled tubule in the blood. If the blood is dilute, e.g. after drinking large volumes of uids, less is reabsorbed from the ultraltrate resulting in a greater quantity of dilute urine. If the blood is too concentrated, e.g. after excessive sweating or eating large amounts of salty food, more water is reabsorbed, resulting in a smaller volume of more concentrated urine. 181 835292 CSEC HSB Unit B Topic 5.indd 181 08/01/2015 16:10 The functions of the Homeostasis kidney Figure a B.5.2.6 shows a summar y of reabsor ption along t he whole lengt h of nephron. Ultrafiltration: salts, from urea, the small molecules, glucose, blood into amino e.g. acids, Bowman’s water, are filtered capsule some salts water, some reabsorbed from to renal vein renal artery some water reabsorbed Selective 70% glucose, some are reabsorption water, all of some amino the salts, (under the control of ADH) acids reabsorbed some water reabsorbed urine: salts; mixture moves bladder, p Table in as B.5.2.3 the and B.5.2.6 By It of Table passes way the of the of selective summarising and each of you substance released the the water pelvis, via events and ureter to urethra that plasma, about should in urea, reabsorption blood thinking nephron, what be three occur ultraltrate has able happened to explain uids. Activity Composition of body fluids Look at T able B.5.2.3. Read columns 2– 4 carefully and composition B.5.2.3 along concentrations Written ultrafiltration another compares studying ultraltrate different Summary illustrates nephrons. urine. the the Figure of down through the the kidneys table by looking: 3 ● at the per headings ● down the list of ● down the list for ● across as know? q in is to T able substances each this each blood occurs you that give the units as g per dm (grams litre) diagrams Did for chapter row to filtered form B.5.2.3 fluid: see to to in see how form the left plasma, where the hand column ultrafiltrate and urine are in the concentration of each ultrafiltrate they and then (look at the nephron) substance selective varies reabsorption urine. The concentration of important substances in plasma, ? ultrafiltrate The yellow colour of urine is and urine due 3 Approximate to urochrome, which is Substance from bile pigments. Usually passed morning over is night dark the reabsorbing prevent rst thing yellow kidneys lots of in g per dm in Ultraltrate Urine 0.03 0.03 3.00 96.00 the because have water Plasma the Urea urine concentration formed been Water 91.00 99.00 Glucose 1.0 1.0 0.00 Mineral 0.40 0.70 1.20 8.00 0.00 0.00 (variable) to salts (variable) dehydration. Protein 182 835292 CSEC HSB Unit B Topic 5.indd 182 08/01/2015 16:10 Homeostasis 1 Kidneys Describe from 2 changes plasma Explain 3 the to in concentration of urea, in the glucose and mineral and health salts urine. why: a protein is not b glucose c the concentration d the figures is in is the the for Reabsorption glucose in ultrafiltrate ultrafiltrate of urea water does not reabsorbed and and not mineral mineral occur if but by salts salts in diffusion diffusion is not urine is the highest urine alone. in may Explain the urine vary. how all the responsible. Questions 1 a State b Explain part 2 State 3 five of substances why the five red are cells filtered and into blood the Bowman’s proteins will not capsule. normally be ultrafiltrate. features of the ultrafiltration efficient. Where nephron in that blood the is glomerulus a glucose and Bowman’s reabsorbed, and capsule b most that make water reabsorbed? 4 State 5 Explain the the role why of the the loop of Henle. concentration of urea is much in their higher in the urine than in ultrafiltrate. 6 State five 7 Using parts components Figures of the production B.5.1.6 urinary in the of urine. and B.5.1.3, system list through which correct urine sequence passes the following its nephron. Learning B.5.3 Kidneys and By Kidney failure kidneys quite a lot can of fail blood. if a person They also is fail involved in in people an accident who are in and has intensive lost blood bur ns. and If care, who for some taken of reason able outcome one most become cases of ser iously kidney dehydrated failure are or linked have to had severe hyper tension diabetes. longer not poisoning, However, to to t he control correct and t hree it end will nephrons t he or cease volume or compensate happen fairly to function composition for t he quickly. properly, of t he malfunction, Kidney a person blood. deat h failure can If is be is steps t he be describe functions 2 of Peritoneal over t he t he a “kidney machine” t hat replaces t he is A the kidney kidneys (or necessary some people. Did you renal) for are likely treated in know? ? Acute kidney happens failure is the suddenly treatment type and may with be essential cured. Chronic, or kidney failure associated long-term, kidneys. dialysis function kidney you problems with dialysis in of which t he t he body’s own abdominal membranes take with transplant from a compatible other need is diseases, hypertension kidney. may 3 health why that using topic to: no ways. haemodialysis this explain appropriate 1 of able associated ● have the should ● The outcomes health and such as diabetes life-long and dialysis. donor. 183 835292 CSEC HSB Unit B Topic 5.indd 183 08/01/2015 16:10 Kidneys and Homeostasis health Dialysis Figure B.5.3.1 between dialysis used, t hose t he ar ter y provides drawn shows forearm machine but Before an his rst to an into a a and in patient and t hen t he of t he or site dialysis a leg dialysis forming accessible on kidney machine. returns neck course vein t he an to a may a vein. also surgical external t hrough machine machine. Blood Veins be p Figure B.5.3.1 dialysis A treatment patient at a vein in t he procedure or t he t hat ows arm tubes into are is r un t he usually performed ar teriovenous individual’s returned when dialysis blood Notice a used. shunt which and from it blood has to join stula. been can This be ltered. machine pump having special clinic arm used Did you dialysis know? ? fluid vein Kidneys may be damaged when artery people such have as chronic diabetes pressure. If the after a serious may happen diseases and high kidneys blood fail, accident, e.g. fistula death fresh in dialysis minutes. fluid p Figure The B.5.3.2 diversion vein so it is blood to stula may an A ow may small t he diagram high for to be t he of to make a to what blood t he happens into even as a a t heir t hat and kidney strengt hens need t hen to back lifetime. Some veins not are dialysis be into t he wall inser ted t he of for body. t he t he The people cannot have suitable. Instead a blood place. (an anticoagulant) prevent blood clots may be from put into forming t he and stula obstr ucting shunt. dialysis the fluid same in salt concentration (approximately and as glucose the Figure a B.5.3.3 kidney represents machine. The t he inside blood from of a blood) patient It blood during vein cannulas machine years, stula in heparin procedures take kidney many graf ted showing pressure able into last dose between of better operation vessel A from is is in t he separated centre from t he par tially permeable uid t he of t he diagram. dialysis uid membranes. by This patient has blood to concentration components Because blood same t he par tially blood as is permeable “normal” of blood. surrounded by membranes: patient ● blood will dialysis proteins not leave and t he red blood patient’s cells blood fluid out ● partially (allows permeable urea to membrane diffuse down there will be no net movement of soluble substances such as glucose a because their concentration in the concentration to dialysis gradient from blood fluid) blood is the same as in the dialysis uid p Figure B.5.3.3 A simple representation of the inside of a kidney dialysis machine 184 835292 CSEC HSB Unit B Topic 5.indd 184 08/01/2015 16:10 Homeostasis ● any Kidneys excess dialysis soluble uid by substance diffusion in and t he so be blood, e.g. removed urea, from will t he pass into and health t he blood. Did you know? ? Kidney A transplants transplant donor) and We involves surgically removing a inser ting it healt hy kidney into abdomen t he from one of a person person can This people donate do not work (t he recipient). For skilled surgeons t his is a relative problem arises, t he rejection. If t he donor t he and action sterile d ay Alvin unit I of in a main of hospital be blood and white t hem, reduced cells attack cells by t he for recipient, several life large up areas of his of can job enable d i alysis as a they not t he people t he to t he of tissue nurses nurse is nursing in t he dialysis patients to manage disease treatment dialysis water who have just from died. operation of types of suppress to in prevent working. suffering kidney failure in a to renal and as including clinic well t heir as for families. administer t he t he providing My dialysis t he receive from treatment and star t to t hat super vise patients t heir nish. for administering machine, which uid ushes Figure from takes t he on kidneys. t he job of The t he B.5.3.4 for monitoring a kidney kidney. patient’s is always rst ver y time, for any signs of patient for kidney dialysis hard when especially we when meet it’s a a new child patient or for a young the whole machine I They vital are of ten ver y frightened of am signs and we have to put them at ease. Some and patients monitor a and experience responsible Preparing injections, toxins person. essentially also match. taken t he recipient the I good consultant. responsible excess a are tissue cells which It a called failure t he dr ugs t he is p am have kidneys nurse dialysis treatment peritoneal t he kidney a nephrology dialysis and for dialysis via a hospital. suppor t Dialysis I if transplant recipient attack in keeping af ter is t he This matching or days system in it. will resulting immunosuppressant immune transplants responsibility clinics a lives. the all patients home destroy can cells body ’s white tissue recipient’s injecting white in cer tain foreign and rejection t he describes in cover kidneys study setting wit h t he kidney normal Case A Tissue if as t he kidney recipient, while Successful kidney unchecked, conditions infection lead however, new transplanted transplant. their needs operation. people recognise one some relatively Other A just that own and straightfor ward with means (t he whose close kidneys survive kidney. can get ver y bored while they are in the unit, infection. so par t In our clinic we see mainly people with chronic to do kidney disease, that’s people who are on renal dialysis to. all the time and who come for treatment about spread of or our they Some of job are our them is making near someone patients around sure to are they who ver y keep have they funny ever yone something can and talk we tr y to cheerful. three times a week. Therefore you see a lot of the We have to job I most. be good at teaching. It’s t he par t of t he same patients from week to week. It is ver y much like Some of our patients manage t heir about routine, rather like an assembly line. I hope condition at home eit her wit h a haemodialyser or by that doesn’t sound bad, because we like many of our using peritoneal dialysis (PD). We teach t he patients patients and it is good to see them and help them keep how to perform t heir own treatments at home and in good health. 185 835292 CSEC HSB Unit B Topic 5.indd 185 08/01/2015 16:10 Kidneys give and Homeostasis health t hem t he knowledge complications occur to during know t heir what to do if There any are needles treatment. many we use “shar ps”, to stick especially into stulas t he and 15-gauge graf ts. PD is not the same as the haemodialysis, which you There is a lot to learn. Dialysis nurses must have a can see in the photo. PD is different because it’s the comprehensive knowledge of kidney disease and be patient’s own membranes that do the dialysis. The able to apply this knowledge every day at work. We peritoneum is the lining of the abdominal cavity, a need to have quite sophisticated technical skills to kind of bag that holds the organs in our abdomen. operate the complex machinery and to work with the Dialysis uid from a bag is run into the body with tubes many types of intravenous lines required. It’s denitely running into the space around the body organs – the a specialty that has its own demands. As lead nurse I peritoneal space. Substances are exchanged across the have to be good at communicating with our consultant, blood vessels in the peritoneum and after a while the our engineer, technicians and other specialists, such as used solution is run out again by placing the bag on dieticians. Sometimes we are called on to give treatment the oor. PD gives patients much more independence to patients with acute kidney failure from another area as they can do the procedure at home and get on with of the hospital. That is always quite exciting and very their lives instead of travelling to our clinic. I enjoy different from our day-to-day job. visits to my patients who are on PD; I am always treated Questions as part of the family. There not are so give downsides easy t hem t heir to to manage and instr uctions weight, you nd t his to job. Some however look t hey af ter have patients many t heir times diet completely 1 What you 2 Explain and That can get fr ustrating. You get used meant by t he term intravenous? how peritoneal dialysis differs from haemodialysis. ignored 3 you. is are to Why do dialysis patients need advice from a seeing dietician? t hem so t hem if of ten t here risks to your staff and t hat is if you can somet hing own healt h patients. There wrong. and is soon a t he lot tell by There healt h of risk looking are of of also at 4 t he ot hers Explain failure – blood, more so t han in general difference chronic between kidney acute kidney failure. exposure 5 to t he and hospital Suggest how t he risks of infection in t he renal unit nursing. are kept as low as possible. Questions Talk about ? 1 There is a shortage of Suggest to for transplant operations. people people to Do think you Discuss friends have donate this and this with paid their is person who depends on dialysis should not be allowed eat salted of potato dialysis chips or drink cola other than during the first two treatment. poor kidneys. 2 right? your a Some hours wealthy why kidneys family, Explain carried the out 3 What are 4 Discuss ways by the a in which kidney dialysis is similar to the functions kidney. advantages of a haemodialysis, and b kidney transplants? teachers. which the factors people donated after for and have to their death. opt against out if a they system do not used wish in to some have countries their in organs 186 835292 CSEC HSB Unit B Topic 5.indd 186 08/01/2015 16:10 Homeostasis B.5.4 Homeostasis Homeostasis Homeostasis wit hin t he is t he body. It (osmoregulation), Learning maintenance includes of a control constant of t he internal water blood glucose concentration, carbon dioxide in balance body By environment of t he blood temperature and of t he define is necessar y so t hat our cells and t he enzymes in t he are specic mechanisms to this topic you to: the term maintain t he levels of t hese factors. the homeostasis concept of homeostasis body explain efciently. of There of able explain ● function be blood. ● Homeostasis end t he ● concentration the should outcomes the importance negative feedback All mechanisms t hese mechanisms of homeostasis share common features: ● ● A specic sensor t hat detects t he value of t he factor being describe monitored. Any deviation from t hat t he is t he desired value ( norm or set point) is corrected more or less The corrective mechanism explain involves negative feedback various mechanisms we the have for homeostasis ensure water t hat our and constantly necessar y function wit h t hat temperature t he efciently. oxygen carbon of t he and dioxide cells and It is and t he impor tant nutrients ot her pH of t hat t hat t hey wastes t heir are t hey are need. It regulation the blood describe the regulation dioxide in the of blood. supplied is removed. surroundings in cells carbon sur vive blood (osmoregulation) ● The of regulated maintained. of ● is so ● norm the concentration glucose ● how also The need to be Key terms ! kept (see constant Unit so t hat t he enzymes in our cells can function efciently B.1.3). Homeostasis (near) Negative the feedback constant best way to understand negative feedback is to t hink about our The Our body temperature uctuates a little over t he course day, tending to fall at night and rise in t he morning. It increases in the temperature take exercise and af ter eating a meal. Some women notice t hat temperature rises when t hey ovulate. Figure B.5.4.1 shows wit hin occurring about half a over degree a of period 37°C, of we time. have To keep t he mechanisms body to in if it falls and decrease t he temperature if it for 37°C. mechanism the temperature increase condition, body such temperature, that A returns to as its body normal value. t he Negative temperature is t hese a uctuations a norm t heir process body for The when Corrective we value body. of body a normal body condition temperature. of inside body. Norm The Maintenance conditions feedback A system in rises. which state control a is change from detected corrective the and actions to normal triggers restore the centre normal body temperature heat state, norm or set point. loss rises body temperature erutarepmet towards set set falls point point ✔ body = Exam tip 37˚C temperature rises body again towards ydoB falls Conditions in the body never temperature below set set point stay exactly constant they uctuate all the time; point heat heat control in a little above and conservation production below the to that say desired level. homeostasis It is is better the centre brain maintenance of conditions keeping or near constant conditions Time within p Figure below B.5.4.1 the set This point graph of shows the fluctuations in body temperature above narrow limits. and 37°C 187 835292 CSEC HSB Unit B Topic 5.indd 187 08/01/2015 16:10 Homeostasis Homeostasis Negative Study ✔ norm tip be Of it all is the conditions temperature the narrowest in that limits our is bodies kept and is of within a reset. t he rose to negative feedback use to air because conditioning diagram in same type ovens of a control corrective Figure shows set B.5.4.2, what point mechanism action, or or which would norm in which actions, represents happen value. if The a change which t he allow from t he homeostasis. internal corrective The factor action t he norm in top to half question taken cause t he opposite (i.e. negative) effect to what was by t he happening. a result, as control t he factor would fall back to and norm fell below value. The bottom par t t he diagram shows t hat if t he factor its norm t he corrective the examples would again have t he opposite (negative) effect, causing it to rise to of norm value. processes. Blood rise its we its the its would action thermostats at is a understand of use off good As can Look above body example feedback triggers sugar regulation corrective above The sugar The concentration carried in t he blood is glucose. mechanism norm negative feedback closely monitored of by glucose t he in t he pancreas blood and is has −3 a norm of approximately 80–90 mg 100 cm −3 blood norm The norm (or 0.8 to regulation pancreas groups and of 0.9 g dm of t he special ). glucose involves liver. t he cells Langerhans (islets cells two are In known small t he pancreas as t he are islets islands). of These negative secrete hormones, insulin and feedback glucagon. fall below corrective norm p Figure B.5.4.2 The principle mechanism of 3 blood negative glucose concentration / mg per 100 cm feedback 120 110 100 90 80 70 eating exercise time p Figure meal B.5.4.3 and takes The changes in blood glucose concentration as the boy absorbs a exercise If the blood glucose concentration increases, e.g. after a heavy meal, these cells detect this and release more insulin and less glucagon. The insulin travels to the liver in the blood and “tells” it to do a number of things, including conver ting glucose As t he a result, Figure If t he blood change glucose glucagon. glycogen blood These blood glycogen glucose and storing it concentration and conver ting decreases as you glucose can see to fat. in B.5.4.3. releases t he to so t hat changes concentration This to glucose. t he are hormone The decreases, travels glucose concentration shown in t he in char ts pancreas blood diffuses increases ow t he t he out and in is and of detects “tells” t he liver restored Figure to t his t he cells t he and liver to into norm. B.5.4.4. 188 835292 CSEC HSB Unit B Topic 5.indd 188 08/01/2015 16:10 Homeostasis Homeostasis blood glucose concentration at the 3 norm large meal followed of 80–90 mg per 100 cm by muscle absorption of glucose contraction strenuous small blood during from exercise intestine glucose concentration blood glucose concentration 3 increases above change 90 in concentration of blood islets of per in the Langerhans insulin insulin and 100 3 cm decreases “tells” the to of islets secretes less glucagon liver of blood glucose mg blood per in and 100 the by islets pancreas secretes more glucagon to “tells” the liver glycogen to glucose fat concentration blood glucose concentration increases blood glucose concentration returns to Key B.5.4.4 hormones insulin concentration Ot her of and within hormones, stress glands. t he Negative or This cells to has glucagon safe e.g. during feedback t he control work per of 100 cm blood together to glucose keep concentration. changes in blood The glucose limits adrenaline, exercise, conver t mg same also adrenaline effect glycogen to on affect will t he liver glucose to t he be blood secreted as term ! 3 80–90 Figure to glycogen decreases p cm glucose detected Langerhans insulin convert and/or 80 Langerhans glucagon convert in concentration islets pancreas less glucose by below change glucose detected Langerhans more mg sugar by glucagon increase t he level. t he At Osmoregulation The control the water the blood; the body content is of dehydrated blood has less water norm, the kidneys water to in and it of when the than reabsorb the more times conserve it in the body . adrenal stimulating blood glucose Did you know? ? concentration. Paul Langerhans was a medical Osmoregulation student, Osmoregulation is t he ability of an organism to regulate discovered t he named concentration of its body uids. It involves t he maintenance concentration of t he body uids by controlling t he water and of t he blood. We are only going to deal wit h t he control of e.g. content by of excessive t he blood. sweating If a person dur ing loses exercise, water t he from blood t heir after islets him. He he that are thought lymph nodes! A year they earlier discovered what he thought t he were water the when salt he content 21, of were t he aged nerve cells in the skin, they blood, becomes turned out defend us to be cells that help to more against disease. concentrated. 189 835292 CSEC HSB Unit B Topic 5.indd 189 08/01/2015 16:10 Homeostasis Homeostasis a hot and There thirsty t hat brain pituitary t he are special detect receptors changes hypot halamus in t he sends in t he hypot halamus concentration ner ve impulses of to t he t he at t he base blood. If pituitar y it of t he brain increases, gland, t hen stimulating gland it to release anti-diuretic hormone (ADH). secretes ADH ADH line concentrated blood by ADH released into travels t he in t he second becoming blood coiled more to t he tubules permeable kidneys and to t he where it is collecting water so t hat detected ducts. more by These water is t he cells cells t hat respond reabsorbed blood from ADH t he urine into t he blood. As a result less urine travels down to t he stimulates bladder and it is more concentrated and darker in colour. These changes are kidney nephrons to summarised in Figures B.5.4.5 and B.5.4.6. reabsorb water into the concentration of the blood blood plasma small volume concentrated is normal of urine staying running on a ver y hot indoors in air-conditioned so body temperature drinking plenty of many soft drinks water high water dilute cold room rises drinking after b a day rate is of lost sweating from the so low blood water is rate not of sweating lost from the so blood blood concentration no ADH in of blood increases concentration of blood decreases blood and little detected by hypothalamus and is detected by hypothalamus water reabsorbed the is blood into by kidney pituitar y gland secretes pituitar y gland stops nephrons ADH into collecting respond large volume to the ducts ADH p Figure B.5.4.5 the pituitary we are a ADH gland in is the b secreted head secreted after little drinking collecting ducts respond by in kidney becoming to water impermeable to water by when or no plenty is reabsorbed from water is not reabsorbed ADH the is kidney becoming ADH urine water dehydrated; in by secreting of permeable dilute blood urine into the blood from urine into the blood of water concentration plasma p Figure B.5.4.6 A flow chart of returns the to showing blood normal osmoregulation 190 835292 CSEC HSB Unit B Topic 5.indd 190 08/01/2015 16:10 Homeostasis Variations Homeostasis in urine composition Key The A composition high ur in e protein due to of diet wil l changes in cre as e deam in a t io n int ake (in cluding ur in e. Some cola, urine ADH s uc h as re le a se t he t he wa t e r-ba se d dr ugs , depress of according su r plus a lc oh ol a mino will an d t he cer tain c on c en tratio n dr in k s) fro m to urea a c ids. result c af feine pit u it ar y of in in a t ea, gla n d in t he E xcessive mo re Diabetes water dilu te c of fee cau sin g in which become more more t his loss, a no concentration of glucose concentrated is exercises t he reabsorbed and weat her exercise t here is in less more t he of t hey will kidneys so sweat. t hat To compensate urine becomes more less people it. sweat is produced, so t he urine is more dilute. In dioxide sweat much more so, unless t hey drink a lot, t he we sleep at night concentrated is reabsorbed is less of urine is as we we do lose not drink, water so gradually t hrough t he sweating blood and becomes breat hing. is by t he kidney so urine becomes more concentrated and t here the receptors condition if cannot t he muc h This bloodstream. you where because nor mal. blood body less prevents People secrete produces ADH t he wit h ADH is t his large secreted kidneys anymore? condition volumes from from Diabetes t he of at r isk dilute vessels of water into insipidus must not be confused wit h sent breathing the ur ine. hypot halamus reabsorbing are insipidus body (see page fails to regulate t he concentration t han mellitus , centre glucose in t he blood at frequency Control of Wit hin t he centre. You breathing medulla at t he the to rate base of t he brain is t he respirator y or breat hing rate can see aware to of t his t he t he position centre, intercostal respirator y of t his region in Figure B.5.4.8. You and centre but it controls muscles sends out and t he rate of diaphragm regular impulses breat hing by depth and elsewhere in stretc h breat he t he in. body receptors The to in centre c hange t he lungs responds t he rate t hat and send to increase sending muscles. to t he var ious muscles dept h of impulses inputs to from breat hing. to t he centre dioxide so t hat we This breat he has t he out. effect The of centre stopping also t he responds impulses to to t he as about instr ument dioxide when our or breat hing go swimming. concentration you hold when your of t he we The t alk, sing, decisions medulla blood, exercise, also whic h play t hat responds increases to a carbon normal Figure in we B.5.4.7 increase the in blood the The carbon on effect dioxide breathing breathing centre in of an concentration is controlled the brain wind t he dur ing to t he muscles by make of returns There p inate. of are concentration lungs the muscles diaphragm breathing are higher 192). and contract sends where intercostal impulses in dehydration. d i abetes of the brain impulses t he to centre t he breathing Diabetes never by in insipidus happens is detected Water impulses What The the increases it. Diabetes is in hot chemical This of for increase more a rate increases concentrated. When is blood. more blood weat her, the the ur ine carbon cold of in and t he concentration In disease control dilut e . person water A is respiration The mellitus there during to term ! factors. carbon exercise or breat h. 191 835292 CSEC HSB Unit B Topic 5.indd 191 08/01/2015 16:10 Homeostasis Homeostasis Use to Figures an B.5.4.7 increase in and B.5.4.8 breat hing to dept h follow and t he rate sequence during of events t hat leads exercise. brain respiratory (breathing) centre the in medulla nerves from stretch in the receptors lungs intercostal muscles u Figure B.5.4.8 medulla in the The position brain, which of the controls diaphragm the activity muscles of and the the intercostal diaphragm Diabetes mellitus Diabetes mellitus is a disease where the concentration of glucose in the blood Key cannot be regulated properly. When this happens people are at risk of having terms ! such a high glucose concentration that they cannot reabsorb all of the glucose T ype 1 (juvenile diabetes This onset) form of in the kidneys. A sign of this condition is the presence of glucose in the urine. diabetes There is caused by Langerhans the to failure secrete of islets are two forms 2 (late diabetes usually to This to form by a of diabetes failure of is cells Type of 1 20. needed. insulin. 1) human Figure t he from in can B.5.4.9). t hat careful control Late-onset 2 The t he liver and insulin controlled B.5.4.9 A which dispenses doses of insulin girl fixing carefully into the a mini a treat can people side us to administer of t he insulin diabetes produce on age are was at synt hetic t his insulin insulin greater under of effects. infor mation dose much glucose to enabled to in injections juvenile-onset lead more r ight found daily see for just t he independence page t hem r ight and 305. (see times more concentration. 2) d i abetes to be taking in by is usually t he t he body produced dr ugs and found pancreas to is no longer get t he keeping to in over t he age adequate, but cells respond same a people of ten to effect; low-sugar it it, of meaning can usually in t hat be diet. pump controlled blood to have For t he people produced has t his and mini-pump blood elsewhere by usually used 1980s. a is stops but delivers t heir onset) insulin t he giving of (type (late 35. more day, insulin cattle, have This insulin engineer ing since now d i abetes of t he or genetic dur ing Type past, pigs insulin Diabetics onset) production In Advances Figure (type (juvenile The obtained p mellitus. onset) caused respond diabetes insulin. Juvenile-onset T ype of of Mature-onset weight of ten diabetes improves is of ten t his associated wit h obesity. Dieting to reduce condition. 192 835292 CSEC HSB Unit B Topic 5.indd 192 08/01/2015 16:10 Homeostasis Case study Di abetes The is diseases diabetes over t he suffered t hat t he of in type 2 by Trinidad per increase cent is of cases This is is c hances of use t he not easily tobacco of is a in of Similar world of t he all long-term and rates of world. adults It has 15%. 170 000 causes Jamaicans 15 of statistics and deat h have been Caribbean in living becoming t he in between leading t he Car ibbean, you in preventable. and 12% over t he mor tality excess aged disease by least t hat t he diabetes or at 2012 deat hs. in of highest t he ot her of among yout hs one all “stressed” t hat t he diet, It in par ts and Tobago 7000 many and prevalence diabetes stated countries diabetes. are to nearly t hese one The and due diabetes. hyper tension t hroughout Caribbean and being and unhealt hy rapidly Minister 13 diabetes, exception. ot her of wit h deat hs 25 for from infected, lifestyle in t hat major ity of no from accounting The is Healt h age repor ted people t hat and Jamaica’s are of Caribbean increasing estimated 24 the Caribbean t hese is in number diseases t he Homeostasis can catc h pover ty. The diabetic har mful four are use as elsewhere, by This is main being a physical of disease r isk of factors inactivity, p Figure blood alcohol. her A sur vey of of schoolchildren teenagers admitting Statistics Data leading at from was between per to from t here were an one 2002 and of of wit h show 100 2006. In for and more four Margaret of deat h Trinidad t he Bahamas Princess average cause 100 000 least t he t he in over weight, risk t he t he of consequences Hospital wit h a in a Bahamas, ages found 40% all t hat A nurse checks concentration of the one of patients 17% teenagers factors. amputations all Tobago t han B.5.4.10 glucose Nassau year as a diabetes rate of of diabetes. shows result is t he about t hat of diabetes f t h 30 deat hs people. Questions 1 What is t he difference between being 2 What is t he difference between type 3 What is meant 4 Explain t he diabetes 5 A per person hungr y, These t he 6 Diabetes A to has 7 A to repor t nd from Caribbean of of and type 2 being obese? diabetes? lifestyle”? expressing doctor lot and of t he number you complaining going diabetes. of people wit h to t he of being toilet tired, more What simple using a test always of ten might t han usual. suggest t hat diabetes? is conrmed given a monitored if t he t he by glucose for person high-salt t hink t his to was ban foods drink t he International governments energy-dense, whet her a usually patient concentration expect t he symptoms is disease 1 and 100 000. goes are “a advantage drinking person test. by over weight next few diabetic? Diabetes or and should glucose and be at t heir tolerance blood hours. How would Federation least limit beverages to glucose What t he would t hey in 2012 or you treated? urged marketing children. implemented be of Discuss not? 193 835292 CSEC HSB Unit B Topic 5.indd 193 08/01/2015 16:10 Homeostasis Skin Questions 1 a State the opposite 3 Use set 4 an role of insulin. effect to insulin. example point, What effect would concentration became 5 If the 6 Copy T ype too blood occurs in Mature-onset Describe glucose 8 Insulin is 9 a in is a By the end of this topic Explain B.5.5 outcomes be able following terms: norm/ feedback. body and the the b cells the if blood a the plasma plasma concentration dropped too low, what process that significantly? using your notes, fill Cause in the blanks. Treatment 1) 2) biochemical test you could use to show the presence of protein and so cannot be taken by mouth. Explain why this insulin injections are not normally given to people with diabetes. why diabetes insipidus can be a life-threatening disorder. Skin you Skin should on by have answers. decrease and, meant that urine. why late-onset Learning high, hormones so. Explain 10 have your mellitus (type (type too are two negative concentration below diabetes what Explain would table Name action, osmosis glucose Juvenile-onset 7 show became low? cells the of to corrective b structure to: The skin is the largest organ in the body and is an important organ in helping ● describe the structure of the us to resist infection (page 322), excrete and avoid dehydration. It also has a skin major part to play in controlling our body temperature. Figure B.5.5.1 shows ● list the functions of the skin a section through the skin and illustrates its complex nature. ● relate the structures of the There skin ● their are t hree distinguish different layers wit hin t he skin, t he epidermis, dermis and functions subcutaneous and ● to between fat heat temperature describe the regulation of sweat pain pore receptor touch receptor hair temperature. temperature receptor cornified layer epidermis Malpighian layer sebaceous sweat gland gland venule dermis arteriole to pressure brain receptor from fat brain (adipose) shunt vessel blood capillary hair hair erector papilla follicle muscle tissue network p Figure B.5.5.1 The structure of human skin 194 835292 CSEC HSB Unit B Topic 5.indd 194 08/01/2015 16:10 Homeostasis Skin Epidermis ! Key Cornied The upper dead of a cells cells loss and from layer of t he extent it t he t he cont aining protects cer t ain terms layer by keratin, t he and entr y t hey are is t he whic h underlying puncture. prevents sur face epider mis is tissues It is of also cor nied a tough against a by This brous The new cells by layer cells is made protein. damage water proof pat hogens. replaced layer. are This fr iction so of t he layer and, reduces layer to water const antly from Skin lost below. body The – (germinal) layer largest covers composed of Epidermis the organ the many Outer in body the and is tissues. tissue of skin. Dermis which Malpighian it such as tissue Inner is layer of the composed of many nervous and tissue, connective skin, tissues, muscle tissue. This is a single layer of cells, which divide to produce replacement cells for Subcutaneous Tissue those rubbed off the surface of the skin. These cells contain the dark pigment immediately below which an the dermis, melanin, which protects underlying tissues against ultraviolet (UV) light. forms provides food insulating layer or storage. Dermis Sweat These glands absorb sur round pores water, t hem. onto t he ions The and uid surface of urea passes t he from up skin t he blood in sweat ducts where it t he capillar ies and evaporates. t hat t hrough If sweat Key sweat term ! accumulates Arteriole on t he skin it is not properly doing its job of removing heat from t he that controls capillaries. Blood Ar teries deliver blood to smaller vessels called arterioles. Blood t hen capillaries not blood to The and us we warm do These from page vessel blood to has ring arteriole a not Ar terioles – and t he shunt increasing dermis. vessels it to lose which in ot her The control heat and its thin wall. Arterioles of are small arteries. capillaries t he ow reducing of it 199). raise air: have Figure t hroughout in muscles to trapped a t he good dense hairs, t hermal body hair insulator. and have to mammals This use is not gives much clot hes a use instead to B.5.5.4). glands glands secrete cracking, bacteria. (see erector (see tissues capillaries contract of t he epidermis. heat Sebaceous supply t hese hair layer as keep to t he muscles dense to enter t hrough conser ve Hairs An of ows not do blood supply vessels muscle into Small body. an helps Overactive to oily liquid called water proof glands can t he cause sebum skin acne and (see which prevents inhibits Figure t he t he skin growt h of B.5.5.2). Receptors There are pressure. receptors They t hat send detect impulses changes to t he in brain temperature, and spinal pain, touch and cord. p Subcutaneous fat Figure the This is layer formed slows of down adipose heat B.5.5.2 overactive tissue loss or which heat has gain cells and acts full as of triglycerides. par t of our This energy Acne is sebaceous caused glands by in skin fat store. 195 835292 CSEC HSB Unit B Topic 5.indd 195 08/01/2015 16:10 Homeostasis Skin Practical T o investigate the Activity density of touch receptors in various parts of the skin Requirements ● two cocktail sandpaper piece of Ask someone 2 Blindfold the sticks to of skin the 3 Make a 4 T ouch list the have Calculate 6 If subject Repeat finger the feels stimuli skin Record had a and 3–6 sole to on of be of number you ten one the success mm If this to use 2, of 1, that the apart mm blunted with two. needs to cocktail Each say area how time. 1, the response in the or each so 20 mm activity. subject 1, back sticks about stick skin e.g. the correct 1, 2, hand each 2, 1, 2, 1. following the list time. responses. rate, the decrease success the rate distance was less between than 100% apart. parts forearm. of going use, on for are The are graduated with subject’s repeat. 30 subject times. will different foot, the either gently the rule, ● touching you 100% mm distance the of Find the out points used in suitable table and body, which the test. e.g. the areas Y ou back are can of best also neck, at repeat with people. Record the density of Heat she cocktail ends them skin, percentage 10 steps detecting 8 to tips, different the to stimulated subject’s the sticks increase 7 of T ell their or made. 5 the he the a adjust volunteer be by into clay; subject. will points the to stimulate many blunted pushed modelling 1 you sticks and and results touch in a receptors in different explain areas of them in terms of the skin. temperature Heat is a form of energy that scientists measure in joules. Temperature is a measure of the degree of hotness, measured in degrees Celsius (°C) although often still given in weather forecasts as degrees Fahrenheit (°C). Heat is thermal energy and how much there is present depends on the mass of material. Temperature is a measure of the average kinetic energy of particles in a material, however much is present. All mammals have a temperature around 35°C to 40°C, but larger mammals have much more heat in their bodies than small ones simply because of their larger mass. You may burn yourself with a drop of boiling water, but the thermal energy in it will not cook an egg. Practical T o compare the Activity energy content of foods Requirements ● eye ● thermometer protection ● mounted ● balance, needle ● heat ● stand resistant ● teaspoon ● measuring ● Bunsen burner ● ruler mm) and mat clamp 3 (if ● weighing possible) boiling tube to 0.1 g (in cylinder (25 cm ) 196 835292 CSEC HSB Unit B Topic 5.indd 196 08/01/2015 16:10 Homeostasis variety ● as Skin of anyone should while in a foodstuffs, mini-marshmallows, (already If dry popped), has not the a be very popcorn potato food investigation or is e.g. to anyone carried room, pasta, bread, beans, nuts, potato, hard bacon, dry cheese. snacks, allergy, included well-ventilated such nuts, with out. although then an The if it is either allergy the investigation too foods should draughty not should the concerned be in be foods the lab carried will not out burn well. 3 1 Use the 2 Clamp measuring the tube in cylinder the to retort put 25 stand at cm a of water into the angle and over slight boiling a tube. p heat Figure air resistant is Weigh 4 T ake 5 Fix 6 7 food the mm on food below goes When the there of out, is food of of quickly stops it and tube a burner, it burning, mass. Burning very efficient foods way in of the finding and above If the instead food of on immediately the their good energy content, investigation for but you to it is a evaluate it. needle. teaspoon and relight the record mounted on Bunsen boiling record water the put a and the end then using the food the re-weigh the heated flame If piece temperature when record 8 small the Ignite 10 a the melt a mat. out 3 B.5.5.3 not heat is likely the hold resistant to needle. it about mat. If the again. stir the water with the thermometer and temperature. a significant this and amount record the of unburnt mass food left on the needle, remaining. 3 9 Empty the the and investigation 10 Record 11 Calculate a tube all your the Use this food to refill using q is a to another table joules (or 10 cm of cold repeat kilojoules) the heat with by more energy the heat cm the temperature C an = m × energy is the Divide specific example: your energy 12 Compare you may Unit you 13 your q B.1.6 official where energy signicant damaging animals to keep in C in × m is the mass (also t heir of of water (4.2 J g water heated −1 deg ), and ΔT is = the used 4.2 × 16 1680 J the with × mass water the in of official they this foodstuff joules per energy came from information burnt gram content or to from find to of of a out find the heat food. the foods website how which (see much energy day). for the differences between your answers and the values. regulation variation effects each ΔT joules, heat 25 packet you a reasons T emperature Any the = by by results on consume Suggest answer absorbed find from increase. q b steps: water: (25 is these transferred −1 ), Repeat foods. following 3 Here water. food. and calculate q where with different in in equation the a results energy it on called body t he in internal, body ’s homoiot herms temperature or core, enzymes or fairly (see temperature page 70). warm-blooded constant despite could have Endot hermic animals) changes are in able t he 197 835292 CSEC HSB Unit B Topic 5.indd 197 08/01/2015 16:10 Homeostasis Skin temperature exercising endot herms of about q How is or you can be in gained in which internal constant or convection explained Ways a or ovulates Table heat (see internal lost and from be 252). (core) t he and gained body of shown and e.g. when Humans body evaporation B.5.5.1 can uctuations, page are temperature in four ways – water. in Figure B.5.5.4. lost. Explanation Radiation Transfer of heat to or from the body to Conduction Transfer of heat to or from the body by direct such the body via moving as Transfer Evaporation know? female lost Convection Did a maintain Heat are B.5.5.1 heat gained environment conduction, terms T able t he when and 37°C. radiation, These of and The loss of ground heat of to heat or or a objects via contact the with air another object, chair from used other to the change water from a air liquid to a vapour, e.g. when ? water Ectotherms their body cannot according to the temperature B.5.5.4 surroundings. Reptiles of are examples of shows some temperature. adjustments the gas exchange system of We t he ways have in which various we respond homeostatic to t he two mechanisms so t hat t he body temperature says near constant. to Our and behaviour sh or of make their surface the extremes in skin which Figure changes the control temperature, uctuates leaves also changes when we are in t he hot or in t he cold to keep a ectotherms. constant temperature. evaporation from the skin evaporation the convection to the from lungs air radiation to conduction to heat air objects ground gained from and through nearby hot food drinks heat generated by shivering heat by generated respiration especially the in liver insulation heat in (conserves u Figure B.5.5.4 How we lose heat, keeps the body heat) radiant heat absorbed fires or from central heating conserve heat and gain heat 198 835292 CSEC HSB Unit B Topic 5.indd 198 08/01/2015 16:10 Homeostasis Responses Skin to heat gain Key If we also are gaining reduce t he heat, t hen generation we of do our heat best wit hin to lose t he it from body. We t he have body term ! and various Vasodilation mechanisms for muscle ● Sweating water – heat energy evaporates from from t he t he body surface of is absorbed t he skin (see by t he Figure sweat and blood t he Muscles in t he dermis relax so t hat hairs lie at against ● (see Blood B.5.5.6). vessels in This t he is skin not much widen to use to allow ow in to arterioles of allows capillaries. B.5.5.5). t he surface of the heat in the cold t he sweat skin tissue to in ● Relaxation t his. evaporates no sweat us. more blood to ow t hrough t he sweat capillaries. Heat is lost by radiation, conduction and convection to t he travels up surroundings. The widening of t he ar terioles in order to let more sweat blood duct t hrough ● More capillaries blood ows is vasod ilation into t he (see circulation Figure from B.5.5.7). stores in t he liver and spleen. shunt This supplies more t he blood needed to go t hrough t he skin t herefore heat. p ● The metabolic rate decreases. This is a long-term effect control generated ● of from Behavioural clot hing turning t he or hormone t hyroxine and means less Figure heat Sweat glands the heat in the cold is respiration. changes loose on t he to heat include tting air taking clot hing, cold drinks, turning off wearing t he less heating and conditioning. muscle Response B.5.5.5 under in t he vessel losing loss to lower relaxes the muscle hair raise contracts the to hair If we are losing heat, then we do our best to conserve p Figure B.5.5.6 Hairs what we have in the body before using energy to produce more. We have various mechanisms for this. in ● heat Blood vessels in the skin constrict to reduce the lost heat by radiation little in the cold heat lost by radiation the blood ow through the skin capillaries. Instead, the blood ows along shunt vessels from arterioles direct to venules. Less heat is lost from the blood by radiation, conduction and convection to the surroundings. The contraction of the arterioles in order to let less blood through capillaries is ● Muscles pulled in up insulator. value in vasoconstriction t he to dermis trap This heat a contract layer gives us of air, so t hat which gooseesh hairs is but a is are good of no conser vation. shunt ● Sweat glands stop lost by The metabolic secreting sweat, so no heat evaporation. Key : ● heat. This can adrenaline rate be and increases stimulated to by Muscles This ● contract the wall of a blood in the wall of a a vessel t he release blood contracted vessel relaxed of involuntarily contraction of in Figure B.5.5.7 skin control to Vasodilation blood flow and vasoconstriction through capillaries in in the the dermis shivering. skeletal muscle heat. Behavioural turning in Muscle t hyroxine. spasmodic generates Muscle generate p ● vessel is on changes t he include heating and taking turning hot off drinks, t he air wearing warm clot hing, conditioning. 199 835292 CSEC HSB Unit B Topic 5.indd 199 08/01/2015 16:10 Homeostasis Skin Written Building a Create table a of the of better Activity table skin. to Y our summarise table could the information have the about following the structure headings, but in the skin Description How the carries Key terms Role The Vasoconstriction Contraction blood tissue ow in into arterioles the brain hypot halamus t he hypot halamus Hypothalamus Part that is thermostat. also controls the as many other vessel does to not a Connects venule ow so an early through narrow an that also from brain t hat regulation acts detect receives as our changes information receptors warning hypot halamus production arteriole t he function t hermostat. in blood There are temperature. receptors The in t he skin. about This t he temperature information of from t he t he skin is t hat t he blood temperature is about to change. The It functions well. Shunt in its brain like body’ s temperature hypot halamus surroundings the in structure out reduces capillaries. of think of in muscle of function may ones. Structure ! and you responds and heat to t hese changes conser vation so t he and coordinates blood heat temperature loss, stays heat wit hin limits. blood capillaries. Tr y this yourself hypothalamus T emperature measures receptors in the skin body temperature Requirements temperature normal temperature decrease temperature increase ● three with <37°C 37°C containers water at blood action just ● thermometer with container ice 3 cold with water, hot container water at 2 1 Put bearable when you put your finger into a it the forefinger of your left hand into the container of ice cold water dilate and hairs the Leave skin up forefinger them for of your about a other hand into the container of hot water. minute. sweats 2 T ake out your container shivering 3 them in What do repeat how temperature, 1 vessels constrict Figure container blood no vessels p room water: >37°C temperature stand for B.5.5.8 negative maintaining This flow feedback body chart is shows important 4 What of fingers water, and immediately putting them in, put taking them them alternately out and into then the third putting again. you the does feel? Do exercise this tell not and you tell anyone, compare about the what ask another you receptors family member to felt. in your skin? in temperature 200 835292 CSEC HSB Unit B Topic 5.indd 200 08/01/2015 16:10 Homeostasis Case Skin study Benzinger ’s The experiment Amer ican Research Institute exper iment to temperature in t he In this that the Benzinger Mar yland out changes experiment, was the taken in nd T.H. in whet her or relied t he t he worked 1940s. at He t he devised hypot halamus entirely on Naval an could infor mation Medical ingenious detect from receptors skin. kept Readings and scientist, were rate by at a taken of naked of Do a volunteer tr y this down above temperature, The the temperature temperature not lay temperature skin sweating. placing eardr um. a constant probe into yourself. of in his a special body container temperature. hypothalamus the the temperature hypothalamus outer Periodically ear the so that can it volunteer be touches drank a p Figure The quantity of iced B.5.5.9 area results high of t he external experiment are in Figure B.5.5.10. Initially, wit h a is a very controls temperature: of the small many temperature ● ● ● t he internal t he rate t he skin On ● ● of t he internal The rate sent of The t he Note t he body. indicates was the was t he temperature t he of the brain that including regulation high low. decreased. hypot halamus. to part functions This high sherbet, sweating t he was hypothalamus. sweat following changes happened. decreased. This The glands was caused by hypot halamus causing t hem t he cooled “sensed” to reduce blood t his t he and rate of reduction in production. skin rate t hat seemed cold body impulses sweat temperature sweating The reaching ● body temperature drinking virtual red sherbet. position The The coloured temperature of t he to increased. This was caused by t he sweating. temperature play little experiment par t receptors in t his (t hermoreceptors) response because skin in t he skin temperature in increased. 38.0 7 iced body 37.8 6 sherbet temperature 37.6 5 4 rate of sweating 37.2 3 yrartibra/gnitaews C°/erutarepmeT 37.4 stinu drunk (internal) fo 37.0 skin temperature 36.8 etaR 2 1 0 36.6 10 0 20 30 40 50 60 experiment to 70 80 Time/min p Figure B.5.5.10 responds to the The results of temperature an of the show that the brain blood 201 835292 CSEC HSB Unit B Topic 5.indd 201 08/01/2015 16:10 Homeostasis Skin Questions 1 Where in 2 Explain t he why body is t he Benzinger hypot halamus? took t he temperature of his volunteer at t he eardr um. 3 Suggest why volunteer 4 What is t he took t he internal t he cold advantage body temperature decreased af ter t he sherbet. of having temperature receptors in t he hypot halamus? 5 How good is t he hypot halamus as a t hermostat? Hypothermia Hypothermi a is t he temperature a result most likely as to mechanisms on occur are mountain temperature money for temperate of or fuel or for term given prolonged ver y fully young falling babies a marked cold are to (t heir people into mechanisms heat-saving to exposure developed), af ter regulation low measures, in temperature exposed water) less drop and effective e.g. body temperatures. to or proper cold people t hey roof is regulation severe old It (e.g. (t heir may also insulation lack in countries). Hypot hermia and deat h. The principle results of t he blood can wit hstand gives in not tops medical in reduced hypot hermia temperature, reduced surgeons a t he or sufcient is metabolic used hear t in and which hear t–lung brain interr upted time rate, need blood to operate. of the ow can lead operations. less for oxygen shor t to By and coma reducing t herefore periods. This Questions 1 List 2 State 3 Name 4 State 5 Describe a the and e 6 six different four ways the part one role of shunt Generally, List three the skin f body that can than the the controls the in following position skin, maintain d of volume the in core constant body temperature. temperature. skin. cold hairs of a conditions: on blood the in skin, the c arterioles circulation, shivering. living in hot those climates who live have in less cold adipose climates. tissue Explain the this. behavioural temperature: to b the and people of in skin. thermoreceptors happens rate, the brain sweating, their advantage 7 of which the vessels metabolic beneath by of what rate functions a changes becomes very that hot; occur b if the becomes environmental very cold. 202 835292 CSEC HSB Unit B Topic 5.indd 202 08/01/2015 16:10 Homeostasis Skin Summary ● Excretion and these e.g if the removal in substances there osmosis ● is substances is too and Examples of of excess have toxic of serious much materials, waste requirements. water effects in the if This they body, are cells products is of important allowed may to metabolism because accumulate, absorb water by burst. metabolic wastes are carbon dioxide, urea and bile pigments. ● The excretory blood, organs reabsorb control the the volume (osmoregulation). ● exchange in is we hot The and kidney artery. ● of through to Each kidney the as of loops If the the a cells dilute most be gives the that is the formed just cells salty are into the controlled pituitary need The to be gland of is other a gas when body. by the supply The through it renal tight blood the renal water, large many form the cells to but be small blood urea filtered. and cells The cells (pores) in ultrafiltrate. and lining passes this almost osmosis. surface down part and large of high blood holes and a at glucose, capillaries, capsule The Ultrafiltration glomerulus area all of of the The and the the tubule water. cells means large when salt as content urine passes by the of the are flows tissues down the the the filtrate through then medulla. the into This to is medulla coiled water, tubule then the pelvis and on reabsorbed by makes Less the collecting reaches the water blood. in second impermeable time in the through straight water of the urine urine flows more into the ureter. the second antidiuretic conserve urine many by to permeable, tissues pelvis on the too have ducts flows conserves and the filtrate and permeability to filtered. ions them concentrated The the and urine of so aorta kidney is the result from transport reabsorbed the tubule the of active in the are Bowman’s collecting into they nephron. increase loop If in filter ions, water the back nephrons. of blood lining ureter. is ● for duct. into lost the flow a and kidneys and body as from blood to including lining as collecting urine are of The reabsorbed. can the coiled osmosis in the which be second the of Henle water After into collects called capillaries easy glucose, The and it diffusion, can cortex capillaries the not by microvilli, that do the quantities the these all have salts blood where the dioxide urea, kidney molecules, this do ducts. of tubule They so small makes ultrafiltrate the skin. glucose from carbon outer tubules, through proteins coiled of as substances glomeruli through and first passed oxygenated the and such cava. pass The lungs contains these through called is excrete Sweat with many lining which that lungs medulla flows Ions the reabsorb ● it has plasma them, ● vena acids, making the kidneys, substances, sweating capillaries veins and are the water alveoli. flows flows amino of The supplied knots pressure. ● is Blood occurs ● the are useful the coiled hormone tubules (ADH) concentration of and which the the is blood collecting secreted increases by ducts the and we water. solution of substances urea and depending excess on diet salts and in water. what It drugs may we contain might taking. 203 835292 CSEC HSB Unit B Topic 5.indd 203 08/01/2015 16:10 Homeostasis Skin ● The skin dermis in is a and sensory an is the these is layer e.g. composed of adipose temperature, protection and maintenance conditions of are of the blood, glucose water of the blood. The content set Any point or norm, change in the sensor. This the which always point The is value triggers return condition negative in the a 37°C of to the is set set to of any point inner functions touch, conditions for of body is the the blood is and the known detected This body. dioxide as temperature. corrective norm. between the in carbon condition conditions or has temperature, stimulate point difference It and an insulation. constant value epidermis, tissue. pressure body these centre its outer concentration the of an (fat) thermal near ideal one control back reduces control actual by a actions that mechanism value and the set feedback. concentration Cells e.g. of pain, core concentration its ● of that underlying control, Homeostasis Examples ● organ reception, temperature ● large islets of of glucose in the Langerhans blood release is the regulated by hormones the insulin pancreas. and glucagon. ● When into the the glucose of blood blood. to glucose ● the and liver diffuses to norm. The the ● If the skin. It also as heat, then diverting activity of the to the blood sweat so body’s is of the as glands so the blood of into can be of lost the blood. It travels of glucose receives and through the skin and also methods surface increasing methods it If of about it. stimulates from by by information receptors (shivering). the glucose concentration away contract convert glucose, flows stimulates to to It heat secreted glycogen skin that surface heat the is cells concentration blood convert hypothalamus to hypothalamus towards from blood production muscle the thermostat. the the secreted to insulin stimulates When restoring diverting the it reduces cells surroundings skeletal the norm. the increases, where This glucagon decreases, such liver the blood the stimulates stimulating increases, it stimulates is of the storage. temperature temperature conserving and it into temperature the concentration to decreases, hypothalamus monitors for returns where which the travels glycogen concentration to glucose It of of the metabolism the temperature losing heat increasing such the evaporation. 204 835292 CSEC HSB Unit B Topic 5.indd 204 08/01/2015 16:10 Homeostasis Practice 8 Practice What will 1 t he blood as it passes t hrough a machine? A carbon B glucose dioxide is added is C oxygen is added D urea removed A Which into to Questions dialysis Section happen Questions substance t he cannot Bowman’s pass capsule in from t he t he glomer ulus kidney of a healt hy is removed person? 9 A B protein C salts D 2 Which Which substances are usually found in t he urine of pelvis B proximal C glomer ulus D loop kidney has t he greatest pressure? convoluted tubule A glucose B salts and amino C salts and water D water Which and and Which of loss t he following from t he combinations helps to prevent kidney dialysis. body? proteins represents Breat hing B Regulating C Removing D Urinating acids Sweat production arterioles A Minimized constricted B Minimized in an example of dilated C Maximized constricted D Maximized dilated homeostasis? oxygen. blood glucose. undigested food t hrough t he anus. Section to empty t he section of t he B bladder. 1 t he Henle proteins A Which of person? heat of t he a 10 4 of A urea healt hy 3 region glucose kidneys control t he water The diagram The dialysis shows a machine used for content membrane is a par tially permeable blood? membrane. A medulla B pelvis blood vessels 5 6 C renal D cor tex What vein will happen A A decrease in B An C Narrowing D Raising increase t he t he as a t he in of t he t he hairs What is A To secrete main B To excrete urea C To secrete water D To protect result of a rise production blood blood of t he of flow of to vessels body temperature? sweat. t he in skin. t he skin. skin. function of t he sweat blood gland? blood and salts. and mineral salts on to t he skin. dialysis 7 Which ar ter y is t he present t han A amino B glucose C urea D carbon out in oils. in skin at t he a from lower renal ultra violet concentration vein? in t he renal a Explain i) acids out dialysis solution in how: t he is ii) dioxide solution light. loss of plasma prevented while proteins blood machine. [2] t he concentration glucose constant while a person and ows is of red blood t hrough t he blood having cells t he is kept dialysis. [3] 205 835292 CSEC HSB Unit B Topic 5.indd 205 08/01/2015 16:10 Practice b Homeostasis Questions A man wit h treatment kidney for 17 concentration 17 failure days. of The urea in received graph his regular shows blood e dialysis how changed t he Explain mains over t he f days. State nal how fairly t he t he blood constant term given conditions in glucose during to t he concentration t he race. maintaining [1] Explain what constant inter- 3 body. re- [3] md 3 a The skin is an organ. is meant by t he 250 rep term gm/doolb b 200 A organ. section [2] t hrough t he skin is shown in t he diagram. eht hai r 150 ni receptor aeru } epidermis 100 fo noitartnecnoc hair 50 erector muscle 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 swea t 17 neurone duct time/days i) State how many times t he person received swea t dialysis treatment; give t he evidence from t he gland graph ii) to suppor t Calculate t he your answer. decrease in t he [2] ar ter y concentration of Use t he man’s urea in t he blood from t he star t t he your iii) until Describe urea 17 iv) t he working. t he end Explain his treatment. changes t hat in t he occur in blood over t he t he Some students you have described. [3] a act as a act as an give iv) t he performance of an The marat hon temperature race. and sense how t he following str ucture of t he skin functions: organ excretor y protection They monitored t he reduce t he glucose water Malpighian dark organ against disease-causing loss. layer is [10] made brown of cells which contain pigment. at hlete’s i) body t he at hlete a during explain organisms changes studied to perform i) [3] t he to ii) iii) c 2 it Show [2] concentration days. of diagram of enables dialysis v ein concentration in Name t he pigment. [1] t he ii) Explain how t he pigment protects t he blood. body. They found increased whole a b t hat t he little, body but State t he body temperature. Explain name how of t he 37°C at hlete during t he 4 a Distinguish between b Suggest effects of t he t he par t of t he brain t hat body c can lose heat during a of students blood temperature negative control feedback. found t hat t he increased and decreased in t he Explain is i) heat and temperature. during t he race, ver y t he of prolonged 0°C. core temperature weat her. hormone to [3] low t hat is [5] prevents [1] Explain how t he content on ver y a exposure [2] body cold dehydration. ii) concentration of below t he in Name an [4] glucose how maintained long at hlete two temperatures controls [1] d why example t he near [4] Explain The temperature remained race. race. c a [2] body hot regulates day. its water [4] but 5 a Define b State t he t he c State t hree term excretion. [3] −3 never d fell below Suggest a what concentration happens to of 60 anyone mg who 100 cm has a . composition of urine. [3] blood factors t hat may affect t he composition of −3 glucose concentration of less t han 60 mg 100 cm urine. of blood. [3] [2] d Explain how the of loss the useful kidney lters substances the such blood as and glucose. prevents [6] 206 835292 CSEC HSB Unit B Topic 5.indd 206 08/01/2015 16:10 Unit B Coordination and control B.6 B.6.1 The nervous system Learning By General features of coordination the are two coordination systems in t he ner vous endocrine describe systems body you the features systems describe main of the divisions system. work in different ways to ensure t hat organs work toget her efciently. They also coordinate the nervous system t hroughout ● t he topic to: coordination of These this able system ● ● be body: ● ● of systems should There end outcomes our responses describe the functions of the to brain. changes Look at in our t he at hlete movements endocrine of his system coordination The surroundings. is t hat and to t he B.6.1.2. must be by t he in specic effector, response of change detect t he Figure will done functioning detectable in body be active his ner vous is a ner ve or t his, t he muscular Alt hough adrenaline, involves internal cells muscle like most of his t his system. systems external stimuli, which perform coordinated. releasing ner vous t he To nely or t hat a t he connect gland stimulus environment), t hat receptor is (t hat is receptor to stimulated any cells effector to give a stimulus. Receptor changes energy impulse travels p of stimulus into energy of along a Figure to the nerve impulse (sensory) Stimulus B.6.1.1 communicate Central nervous receives (brain only), receptor Effector (muscle or system impulse, (brain may activity and neurones effector of the a good nervous system athlete showing spinal on the to and decide coordinates impulse gland) children requires neurone knowledge cord) Helping receptor action links neurones travels Response brings about a along response an (motor) p Figure B.6.1.3 nervous There are ner vous The showing coordination of the body’s activities by the system two divisions system peripheral which Flowchart effector neurone are (CNS) of ner vous attached to t he and ner vous t he system t he system. peripheral can brain, be and It consists ner vous fur t her spinal divided ner ves of system into which t he central ( PNS). cranial are ner ves, attached to p t he spinal Figure B.6.1.2 coordination Central The brain The brain nervous responsible for t he control of many actions. Some of t hese Study t hat we decide to make, while ot hers are t hat we are not aware of most of t he time, if at tip two coordination systems involuntar y are actions flexibility are These actions and system ✔ is voluntar y An cord. examples of organ systems. all. Remember of organs, that they tissues are and composed cells. 207 835292 CSEC HSB Unit B Topic 6.indd 207 08/01/2015 16:12 The nervous Coordination system Figure B.6.1.6 summarises scan NERVOUS t hat shows t heir can be t he main functions. used when regions Figure of t he B.6.1.7 diagnosing human shows illnesses brain and Table photograph of t he of a control B.6.1.1 brain brain. SYSTEM cranium: fused cerebrum Nervous made together of to bones form (cerebral fixed Peripheral Central a and hemispheres): divided joints. Protective into Nervous function System System (brain (PNS) regions dealing with (CNS) and (nerves linking CNS all the specific spinal to parts folded the functions. cerebro-spinal Greatly of cord) so increasing fluids the surrounding body) number of cells the present brain ) r diagram of the membranes r a ( f e s f e a e n s r c imagination r o t e o a r memory around y system e m nervous a Tree o B.6.1.4 t Figure o p brain a u d known i t as o r y thought meninges a r e a intelligence hypothalamus: controls t water h g i s balance and temperature cerebellum: controls balance, posture learned spinal pituitary gland: activities such controls as water cervical numerous balance growth p master (GH). Sometimes known as q B.6.1.6 Vertical B.6.1.1 Figure the shows brain (cerebral hemispheres) the B.6.1.5 The virtual body. ● ● The ● main parts system. see nerves brain: of Look the (in these human carefully yellow) are the nervous and you attached cranial ● can to ● the ● nerves ● Cerebellum ● ● ● Did you Hypothalamus ● ● right side of functions Conscious the body with and head showing parts of the brain and the different parts of the brain shown in thought Association Learning of of and of auditory and information other with external past stimuli experience reasoning Understanding Control visual, incoming of language speech Coordination of voluntary activities Memory Interpretation Coordination Muscle of of incoming balance, information posture and from muscles and tendons movement coordination Controls core Controls osmoregulation the vice body temperature by controlling release of ADH (see brain left side gland) of ● the human of Interpretation pituitary coordinates the e.g know? ? The breathing rate, Functions ● Figure of activities, heart B.6.1.6 of Cerebrum p section autonomic functions T able Region controls gland Figure their vertebra oblongata (medulla): the cord (ADH) medulla and and skills Controls reproduction from pituitary through controlling the release of hormones versa. the gland 208 835292 CSEC HSB Unit B Topic 6.indd 208 08/01/2015 16:12 Coordination q T able Medulla and B.6.1.1 control nervous system Continued oblongata Regulation ● heart ● autonomic activities, e.g. pressure breathing ● rate peristalsis ● gland of rate blood ● Pituitary The Secretes ● ● ADH to collecting ducts Secretes growth Secretes FSH stimulate of the reabsorption of water from urine in the kidney hormone and LH to control reproductive organs The cerebrospinal uid (CSF) circulates within the membranes known as meninges that enclose the CNS. The CSF is also inside a canal within the CNS. p Spinal cord Figure vertical this The spinal cord r uns from t he brain to t he base of t he lumbar region its back and str ucture (see page image can see in Some of t he ner ves glands You have ver tebrae cross-section are t hat t he (see page shown in 156). Along Figure its scan the the showing brain. drawing a Compare lengt h, and identify the in parts Figure of the brain B.6.2.4 legs is and t here along a t he central complex spinal are t heir network ner ves large ner vous to collections lengt hs. The of t he t hem. spinal of solar system. Cranial cord. spinal You At ner ves. plexus near t he system system muscles this page t here to t hese. ner vous and attached brain swellings of met (see t hat and nervous autonomic heart t he of system to arms one internal the by t he B.6.1.5 have is Autonomic will to ner ves attached diaphragm The of Figure are base similar nervous consists ner ves t he is protected with MRI 212). Peripheral This is section of B.6.1.6 t he B.6.1.7 earlier, 133) and is that e.g. in part you in the of the have the ner vous little or speeding control of no up system that conscious and breathing slowing (see controls control page down over. of 191). Questions 1 Name 2 What 3 The are the structures parts of nervous the that body system detect bring can be stimuli. about responses? divided into two different parts. What they? 4 Suggest a 5 Suggest an system role for the meninges involuntary other than the activity control and fluid controlled of the heart in the by CNS. the beat autonomic and nervous breathing. p Figure B.6.1.8 horizontal 6 Suggest what sort of diseases can be diagnosed by MRI scans of the MRI section scan of the showing brain at a the brain. level of the eyes and the nose 209 835292 CSEC HSB Unit B Topic 6.indd 209 08/01/2015 16:12 Nerves, neurones Learning By the end should be and Coordination reexes B.6.2 outcomes of this able topic you The to: are ner vous describe the structure of system specialised Think ● Nerves, how to fast neurones is a ver y transmit your fast and way of information reactions are to control reexes coordinating over cer tain and long t he body. distances stimuli. The Ner ve ver y rapid cells quickly. responses a t hat you need to save yourself from harm and danger depend on t he high nerve speed ● describe the structure of transmission of ner ve impulses. a neurone ● distinguish and between Structure nerves explain the functions different nerve cells (neurones) describe reflex and cell neurones t hat are transmits of ten confused. impulses along A its neurone lengt h. is an individual Ner ves are made up neurones of ● and of ner ve ● nerves neurones Ner ves ● of the mechanism of hundreds of neurones (Figure B.6.2.1). To understand t his, t hink of a a telephone cable. inside t he cable inside a This is t he equivalent of t he ner ve. The individual wires arc distinguish voluntary between and are t he equivalent of t he neurones. Each of t he neurones a ner ve transmits impulses. involuntary action. Nerves Ner ves may Sensory ner ves) central optic t he B.6.2.1 of part complete look a transverse showing bundles carefully circles: A nerve you these are of see nerves If to effectors. Mixed nerves many mixed ner ves, goes from and spinal in pairs are on t he is The word This is either largest the name is pair comes which side pair of of of – a in the body t he all a of mixed t he retina effector ner ves ner ve of t he eye or efferent to is t he t he to carr y of to as ner ve impulses effector ner ves from are t he some central of t he ner ves) ner vous cranial brain). bot h sensor y t he spinal t he brain and motor neurones. Most ner ves are ner ves. down The t he largest neck and cranial into ner ve, t he which t horax and ner ve. (nerve types from neurones and cells) of neurone, receptors which relay neurones t he t he sensory (receptor) neurones which to carr y t he central impulses ner vous from t he system, central motor ner vous (connector) neurones which carr y impulses system from to motor neurones or from one relay neurone to anot her brain). nerves. Alt hough t hey str ucture. Figure this have different from down the as B.6.2.2 functions, shows t he t hese neurones appearance of a have sensor y a similar and a motor nerve brain far as Note t hat bot h neurones have long cytoplasmic extensions from all main cell body known as axons. Axons transmit impulses over long the distances. large sensor y Latin t heir over a afferent wandering. what wanders from of or receptors the neurone. does example from cranial vagus from means exactly e.g. base t hree effectors (e.g. nerves referred t hat Examples from contain impulses sensor y The impulses ner ves nerves to CNS. An receptor impulses know? (effector) are as small neurones carr y cranial 208). to carr y you ? the t hat ner ves. section There All (page (sometimes (leading Neurones you referred transmits neurones ner ves abdomen, Did mixed two neurones. can or neurones system which contain system of (sometimes contain ner vous motor brain. only Figure sensor y, nerves only nerve Motor p be The functions of t he ot her str uctures labelled in Figure B.6.2.2 intestine. are shown in Table B.6.2.1. 210 835292 CSEC HSB Unit B Topic 6.indd 210 08/01/2015 16:12 Coordination The is axons an in and in t he insulator t he home. t hemselves scientist SENSORY control sensor y and rat her Myelin around who Nerves, is a t he motor like t he fatty axon. discovered cell NEURONE and neurones plastic material These are coating made cells are by covered around by specialised called myelin electrical cells Schwann ✔ Study af ter t he You might insulation myelin node tip wonder around gaps in it. After gaps in the why a all the neurone there plastic are has no insulation on of wires. sheath reexes wrap t hem. body and which wiring t hat cells neurones The answer is in B.6.3. axon Ranvier nucleus terminals on relay or motor neurones axon sensory dendrites MOTOR NEURONE dendrites myelin node sheath Ranvier of axon axon terminals on effectors, such as muscles or p Figure B.6.2.2 indicate q T able the The B.6.2.1 taken Structure Structure Cell structure direction of by and The the functions main part activity Dendrites Finely branched Made of their the of Ranvier Simple the of of gap cell motor the parts containing neurone neurone that cells that neurones. of The arrows neurones resulting in to faster all the impulses receive an and the proteins over impulses Schwann form impulse adjacent cytoplasm makes (called membranes between and transmits endings individual surface axon, The the the Part sheath of of Axon Node and impulses Function body Myelin sensory nerve glands cells) long from with insulation. it nucleus. controls distances other neurones abundant They This needs wrap fatty material themselves in around conduction Schwann cells where the myelin sheath is absent cell reexes body receptor axon stimulus Neurones are arranged in a series one af ter the other to form ner vous sensory pathways from between bir th receptor and receptors they always are results and xed, in the effectors. meaning same We that have many stimulating response. As they a are of these pathways neurone par ticular present at bir th, relay neurone we do and not of ten need to involve learn them. protective These actions behaviour, e.g. are called removing simple the reexes hand from a motor shar p object. neurone synapse The ner vous pat h way t h at co nt ro ls a simp le ref le x is called a effector, (gap) simp le i.e. refle x arc and is shown dia g ra mmat ically in Figu re B .6. 2. 3. The central reex or arc t hat shown controls in Figure wit hdrawal of t he hand from a shar p object, e.g. a pin, B.6.2.4. contraction response to t he moves is p pain t he stimulus nger and away ever y from time it t he pin – happens t his t he is gland (CNS) Figure B.6.2.3 representation Muscle muscle nervous system Diagrammatic of a simple reflex arc t he response is 211 835292 CSEC HSB Unit B Topic 6.indd 211 08/01/2015 16:12 Nerves, neurones and Coordination reexes spinal Key white pin stimulates pain receptors to myelin sheaths in relay t he matter: fluid due The neurone skin. grey due dorsal 2 Pain receptors send impulses to control canal: contains 1 and t he matter: to cell bodies root CNS ganglion along t he sensor y neurone. 3 3 Impulses reach t he end of t he dorsal sensor y synapse neurone where t hey cross a synapse to root: carries sensory a neurones relay neurone and t hen anot her synapse sensory to a motor neurone. neurone 4 The to motor t he neurone effector – a transmits muscle in impulses t he arm. 4 5 The t he muscle motor responds neurone to by impulses from contracting motor spinal neurone and effector nerve: ventral root: a mixed carries motor it carries nerve as (muscle) shor tening. motor 5 neurones and sensory 2 neurones Key terms ! derection of impulse 1 Simple reex (action) of behaviour that to learn. automatic A reex of neurones It is arc we The do A piece not and need pain in fast. pin: is the stimulus of pain arrangement p that receptors skin controls a Figure B.6.2.4 A simple reflex arc simple reex. always single of t he t hese The cells neurones. of in t heir It par ts t he spinal t he carries to the wit hdrawal cord in neurone body motor impulses is t he t hese Grey not t here t he white axons is pat hway in matter involving several and t he neurones. are only a hundreds t he inner The t he white cell by myelin. people’s reexes is par t Schwann bodies matter par t outer surrounded mainly wit h fact hand. of surrounded jerk a are neurones matter comparison are shows of called mainly because grey B.6.2.4 neurone, Knee cell neurone spinal is myelin. synapse sensory cause colour fatty Figure motor which appears of and t hat matter white wit h t hese par t grey appears Alt hough relay pat hways outer called same. receptor, of because reex of neurone Medical staff test to see if there is cord anything stretch wrong most common knee jerk with is to their test ner vous the knee systems. jerk reex. The The receptors motor to cap stimulus: impulse stretching the neurone carries knee muscle causes to the impulses impulses carried CNS immediately and triggers muscle the impulses motor to ● stimulus – knee cap wit h edge of hand ● leg a receptor be divided into: a blow a to t he special tendon reex just below hammer or t he t he – t hat stretch extends receptors t he in leg t he t high muscle stimulated sensor y spinal ● The can contract are B.6.2.5 B.6.2.5) neurone tendons Figure (Figure in ● p reex the reflex arc that controls the knee jerk reflex motor to t he tiny ● ● neurone cord neurone effector gap – carries ner ve impulses to t he (CNS) – carries af ter known as t he a t he ner ve impulse impulse passes back over a synapse effector – this is a muscle in the leg which contracts response (There is no – t he relay lower leg neurone extends. in t his reex arc.) 212 835292 CSEC HSB Unit B Topic 6.indd 212 08/01/2015 16:12 Coordination and control Wit hdrawal of examples spinal Reexes pupil of t hat reex t he hand from a painful object and t he knee jerk neurones and reexes are reexes. involve when Nerves, ner ve t he iris pat hways changes t hrough its size t he brain according to include t he light t he intensity Key term ! (see page example These 231). of a The production cranial simple reex of saliva when you smell food is anot her reex. actions are referred to as involuntary actions. Involuntary action that no we have Behaviour conscious control They over. are not The controlled by conscious Practical activity knee jerk t hought. reflex Requirements ● a stool or chair a ● reflex any ● willing 1 Ask Hit someone It only kick. (if of you can borrow one), but not hammer to sit with his or her legs crossed so that one leg can freely. the side sort volunteers swing 2 hammer other leg of takes T oo just your below hand. about fast for 50 you the Try knee this on cap a milliseconds to time with variety the of between hammer people the tap to or, if test and not, their the use the reflexes. start of the leg it! p Practical Measuring your Figure B.6.2.6 The knee jerk reflex activity reaction time experimenter’s hand Requirements ● a metre ● a measuring Y ou need ruler to work experimenter investigates These or in and the First ask 2 Read a the ruler to other are carry is the to a blindfold ● a stool this faster or chair investigation. of the One experiment. reacting – eyesight person This or is the activity touch? experimenter. draw a instructions for your results. and ● subject is the fingers out the which for subject table move pairs question through devise that the cm (cm/mm) the instructions 1 50 tape line down below are centre carefully Explain thumb the to the mostly with of your subject in the each thumb. subject that the forearm. and muscles There are mark long tendons between these muscles and the points of insertion on on thumb the phalanges. subject’s rests 3 Ask the your left 4 subject subject is to sit right sideways handed, at start a bench with that or table hand; if as in not Figure then B.6.2.7. start with on forearm bench If the hand. Hold the subject must ruler vertically should be not opposite be the between touching line on the the the subject’s ruler, but thumb the zero and forefinger. mark on the Y our ruler thumb. p Figure B.6.2.7 213 835292 CSEC HSB Unit B Topic 6.indd 213 08/01/2015 16:12 Nerves, neurones and Coordination reexes 5 Ask go the of subject the ruler. forefinger. distance 6 at you. step significantly Can find 8 Blindfold 9 Use the travel tips Use your brain of the any grip thumb the times. and the result at the reason when ruler mark Look from results and tape eye and results detecting six mark is in the why the your If the ready thumb ruler and let and agree the table. results there calculate are between on others. you control and so, are agree these any mean. are such Use if you think anomalous results? T able B.6.2.2 to time. measuring the must the different subject from zero Record anomalous the the or think reaction (a) to you any your five the subject any are at where between Ignoring 10 The Look 5 look Repeat results. 7 to and to repeat to to estimate the then from of the the the 5 the middle calculate stimulus steps of to 7. distance the brain to the speed at which falling ruler that forearm impulses and middle with the the (b) of take from the and to finger forearm. impulses eyes the take then when with the fingers. 11 Suggest the muscles in Make 12 Evaluate not 13 q Key sure very There pathways the that your times with ruler T able use about numerous reaction the you and the investigation good are taken forearm to by (b) the correct by nerve from impulses fingertips terms saying to from what (a) from muscles the eye to the forearm. in diagrams is good about allow you it in and this Unit. what is it. web visual sites and apps that Try them to stimuli. see how to the test your results agree test. B.6.2.2 Distance Time Distance Time Distance Time Distance Time /mm /s /mm /s /mm /s /mm /s 10 0.045 110 0.150 210 0.207 310 0.252 20 0.064 120 0.156 220 0.212 320 0.256 30 0.078 130 0.163 230 0.217 330 0.260 40 0.090 140 0.169 240 0.221 340 0.263 50 0.101 150 0.175 250 0.226 350 0.267 60 0.111 160 0.181 260 0.230 360 0.271 70 0.120 170 0.186 270 0.235 370 0.275 80 0.128 180 0.192 280 0.239 380 0.278 90 0.136 190 0.197 290 0.243 390 0.282 100 0.143 200 0.202 300 0.247 400 0.286 term ! Voluntary behaviour actions that are Pieces decided Voluntary actions In simple of by contrast to reexes, voluntary actions are decided by t he person the and controlled by t he brain. They involve t he cerebr um of t he brain, where brain. conscious t hought occurs (see Figure B.1.6). 214 835292 CSEC HSB Unit B Topic 6.indd 214 08/01/2015 16:12 Coordination Unlike t he since great a when you impulses a to xed to t he down wish t he how may person see of brain. about motor to nature be you Copy a table T able help you. Y ou might need. Y ou to need to reexes, you can know, brain voluntar y result t he t hen from receptor a is processes actions single t he t he are which and reexes complex stimulus, eye neurones e.g. sends information and makes respond. different may to depending decide t he your to call muscles response on out; how t he controlling will be you brain feel. will speech. If you send If you wish impulses do not different. activity summarise B.6.2.3 can simple The person Written Making of to neurones t he Nerves, responses someone response see control variety see decision This and and use also ll in other carry information the blanks. chapters out some of on simple The rst this book research to row to nd reflexes has been gain other the done to information examples of you simple reexes. q T able B.6.2.3 Comparing Reex 1 reflexes Stimulus W ithdrawal of Pin prick hand Receptor Response Purpose Pain Arm Protection in receptors skin muscles contract against further damage 2 Production of saliva 3 4 Blinking of eye Narrowing (constriction) of 5 Relay are pupils Knee jerk neurones found shows a are entirely relay quite different wit hin t he from CNS and sensor y rarely or have motor neurones myelin. Figure as t hey 6.2.8 neurone. dendrites Questions 1 Use Figures B.6.2.1 and B.6.2.8 to explain the difference between a cell nerve 2 3 and a a Name b Describe Describe a simple body neurone. the the two the functions role reflex neurones of such the as that of these neurone the control in the knee jerk reflex. neurones. Figure removal of the axon B.6.2.8 hand in coordination from a painful or of hot object. 4 Name 5 Give 6 List three an other example three simple of a differences reflex actions. voluntary between synaptic action. a simple reflex and a voluntary endings action. p Figure B.6.2.8 A relay neurone 215 835292 CSEC HSB Unit B Topic 6.indd 215 08/01/2015 16:12 How neurones send Learning By the end Coordination impulses B.6.3 outcomes of this topic How neurones send and control impulses you Coordination should be able to: how an If ● explain you have conrmed passes down a explain how an impulse a t he passage wire, t his as by once it of occurs activity on knew impulses over tap tapping It is t he Now line of A Mexican 5 as long – reaction ner ve along axons distances wit h people you t here t he can wave to t heir between can. ner ve in to have t he times impulses in B.6.2 travel you ver y will fast. have In is like t he ow of direct some current in a t hin circular str ucture. t he table: increase You are t he cannot always not continuously. star t wit h a frequency make shor t a tap at and You a tap continuous spaces of can slow model frequency, slightly noise silence faster. by af ter each tap. impulses. do a a of your Mexican competition fastest star t pulses t he members ever yone Mexican ‘reset’ all shor t on Then, you nger; need get as in nger seconds. your you travel your fast same and gaps B.6.3.1 impulses tapping ever y Then Figure t he already synapse. However, p you gets a across what neurone ways ● completed impulse wit hout position. (im)pulses class or wave. If and any in nd errors. ‘Resetting a t he group you can out To star t of who do friends. get t he two can is a a ever yone why in teams transmit wave, position’ Stand large t here has are neurones. wave How a Think of are in r un t he your t he your neurone lengt h feet. An neurones All of from do It is by electrodes ‘giant’ into motor t here its study cord is from and to about 1 t he distance instead, like in metres mammals So, shor test from 30 t hat animals are The millimetres up half study. as ner ve t hem. t hey are mm in neurones lengt h. base of long in its do diameter t he in your body longest spinal t here cord must to be body. in use not The and covered scientists squids This transmission troughs When to shown enough is of t he They movements is of detected end. boosters neurone are to into ver y were acted neurone. A to t hem to recording t hat neurones few myelin have t hat which neurones taken myelin, transmit but t hey impulses fast. neurones neurone least Inver tebrate possible putting a whale at t hat neurones. just spinal blue extend neurones reasonably some are your difcult squids. have of long t hem of They adult t hat t hese makes lengt h eyes. works in in scientists ions Figure neurones similar electrical t he stimulated t hese uid to all decided across current t he taken seawater stimulated pulses eventually of keep a one t he t hat end way r unning of t hey of t he squid sticking t hese along what membranes ow from and t he t he were neurones lengt h of t he B.6.3.3. by signals a chemical t he signal neurone will sent send across an a synapse. If impulse. + This star ts wit h depolarises along t he responds p Figure B.6.3.2 A squid t he way t he an inow membrane. neurone, by but t he to neurone sodium This t his depolarising down of give (Na ) across depolarisation soon just ions decays. t he like The impulse a star ts next a Mexican t he membrane. some patch ‘boost’. of This current This owing membrane continues all wave. 216 835292 CSEC HSB Unit B Topic 6.indd 216 08/01/2015 16:12 Coordination Af ter can each help table and control patch to again of boost or How membrane t he next resetting has depolarised impulse. yourself for This t he is like next it has to raising Mexican be repolarised, your nger wave. The to so tap neurones send impulses it t he ✔ Study tip neurone + does t his ‘resetting’ by allowing potassium ions (K ) to ow Your out. nerves batteries. If this constant ow of sodium ions into the axon, and potassium axon, continues impulses. of the So, the pumping sodium too long the neurone cannot send any move proteins ions The to in only neurone fast the bring ions it out uses and membrane ATP from potassium pump sodium respiration ions ions in by out to recharge active they itself transpor t. pick up by As the potassium at where t he conduction sodium and use ATP potassium to maintain gradients is why for much consume is the concentration depolarisation. of the used energy by your This you nervous system. in. places is time, rechargable more ions all like constantly ions to out are They t his nodes of of movement Ranvier of (see ions Figure occurs in B.6.2.2). a myelinated This results in a ver y impulses. Synapses As can 212, be seen impulses adjacent impulse ner ve transmitters neurone. 1 An cells. also If end known we B.6.2.3 able to Figure t he t he also impulse t he at cause This Figure be cells. ar r ives transmitters, muscle from must get and B.6.3.4 of as a at consider reaches t he t he shows neurone it B.6.2.4 gaps how t he t he end of t he junctions knee of jerk t he on pages (synapses) t his causes neurotransmitters, depolar isation occurs Figure across is t he on achieved. release to surface between 21 1 its of When an chemical target cell. membrane motor and between of These t he neurones next and reex. sensor y neurone from t he tendon in repolarising depolarised section section knee. potassium 2 The arrival of t he impulse stimulates t he vesicles containing to move towards t he next to depolarised ions transmitter sodium substances section be ions membrane. p Figure B.6.3.3 impulses. direction motor The Conduction arrow taken by of indicates impulses nerve the along this neurone nerve synapse p Figure B.6.3.4 3 The vesicles 4 The transmitter 5 The transmitter motor 6 If Conduction fuse neurone t here is to t he to no impulse and synapse membrane diffuse substances bind sufcient impulse a substances and an across t he t his a to muscle response t he proteins t heir t hen t here might is on t he a contents. synaptic t he depolarisation and as release across depolar isation, leg no causes and of membrane t he motor if you of t he membrane. neurone response. happen gap. If not, tap t he sends t here knee is too gently. 217 835292 CSEC HSB Unit B Topic 6.indd 217 08/01/2015 16:12 How neurones send Coordination impulses 7 Enzyme molecules transmitter. t he chemical means t hat Drugs dr ugs of chemical t he ot hers more Case of t he by t he many dr ug in interacts wit h t hey proteins. as Once system Do for and on Nicotine in This therapy: the getting dangers of a tar nicotine and fix without t hese at synapses. t he of again. This neurone. time Some t hem break between stops This impulses (see t hem block t he t he case down. action study) You will and read is t he t he of blood, of its bind of It t he hear t. There acetylcholine. molecular shape. This cells str ucture means molecules proteins receptor It of also t hese be t hey binds t hose system. may to in are of t hat is ver y nicotine acetylcholine called binds In to small receptor from some t he receptor detect experience. reaches of t he stimuli, receptor autonomic similar ner vous receptor concentrations, proteins. t he responsible nicotine way be to not t he t han The adrenal for t he results gland greater Wit hin t he just brain effects of smoking a such few on a to so ot her is of for ability 10 it to seconds can way have its pat hways up in to to t he t he so gives a t he in smoke. hours t he t he at blood nicotine lungs. nishing 16 in get B.6.3.5). tobacco t hrough transmitters of Figure nicotine t hroughout par t (see inhaling pass absorbed intake t hese of quick has minutes which of continuously dr ug being repeated dopamine, up dangers concentration quite wit hin give t he worn lower Stimulation and action release These adrenaline say because has also nicotine wit hout can rat her is t he quickly. one continue smoke activity ver y are is B.6.2.5. usually glands. smoke, a B.6.2.4 similar especially ner vous dr ug t he released t hat wit h in touch. smokers patch This called pat hways. t hem which are a synapses is Alt hough has at substance down brain t hat substances transmitter Figures synapses. secretion patches to it This slow t he adrenal disappear need in t he central t hat blood, Tobacco replacement t he produces system. nicotine Nicotine of used D.7 . nicotine. and into in t hat confuse patches time. see across synapses types t he is cigarette provide smoking; can aler tness, Some t he space mimic transmitter proteins pain t he inhaling into stimulating shor t t hat Topic acetylcholine, concentrate B.6.3.5 not increased increasing Figure t he diffuse increases t he some acetylcholine. you nicotine They in neurones in effects a molecules be system enzymes common is proteins of t he synapses absorbed an be neurones acetylcholine, light, proteins are wit h tobacco to such always t he to synapses most different when constantly down ready neurone. actions system synapses also The and t he released are wit h break recycled control study ner vous at are transmitters, dr ug Nicotine One synapse nervous interact interact about will next the Many t he transmitter t he and at products t here stimulating p The and into skin The and effects cigarette, a t han of causing day. t he called people brain. One reward a good of ner ve feeling, carbon which is why smokers repor t feelings of pleasure when t hey smoke. It monoxide should t hat be are noted much t hat less many harmful ot her to activities activate t he reward pat hway healt h. 218 835292 CSEC HSB Unit B Topic 6.indd 218 08/01/2015 16:12 Coordination Nicotine but and does ot her control not called suggests, an is and breaks stay for longer and levels t he in so in to t he have receptor t he effect monoamine enzyme. down proteins smoking bind substances compound The This synapses having brain is a oxidase enzyme dopamine. proteins of This is means effect. presumably (MAO), found continually greater dopamine t he levels which, in t hat desire a as its name in t he molecules to of t heir keep why people explain why there brain dopamine receptor high reason system receptor, of synapses stimulating The one for decreasing endocrine get dopamine addicted to quickly. Questions 1 Use Figures synapse 2 What 3 Suggest 4 Explain dr ug in are to B.6.2.4 the t he and knee dangers of reex to and inhaling how nicotine increases why nicotine patches t he brain as Explain why t here 6 Explain why smokers resor ting to What t he are banned aids are in smoke people’s are enzymes cannot such as not t hey at just nicotine advantages because two the into hand t he only one reex. lungs? aler tness as is withdrawal effective and at concentration. delivering t he smoking. 5 7 B.6.2.5 jerk of synapses. give electronic encourage up t heir habit wit hout patches. some cigarettes? young Should people to t hey be smoke? Questions 1 What is the advantage of using neurones for coordinating responses to stimuli? 2 Which two 3 State 4 Explain 5 State 6 How 7 What the B.6.4 role why the is ions are of the name the The in the of a conduction of a nerve impulse? myelin. transmission of the impulse prevents important the gaps passed nerve between over continuous endocrine impulse is like a Mexican wave. neurones. these gaps? stimulation of neurones at synapses? system Learning By Endocrine the end ner vous system is like a system of ‘wires’, each of which goes places. Our ot her coordination system is t he endocrine be distinguish is more blood and like go a ‘wireless’ system ever ywhere. The in cells t hat t hat chemicals respond are are sent t hose out wit h ‘receiver’; ot her cells do not ‘receive’ t he of ‘messages’ which we sent have out by already t he endocrine discussed. system Hormones are are identify They are produced by cells in systems the endocrine glands message. hormones, of ten called many ● endocrine glands secrete describe the hormones different roles chemical of messengers. the endocrine t he that The you into ● appropriate between and (hormone) t he topic to: system nervous which this able between ● specic of glands should The outcomes hormones. and 219 835292 CSEC HSB Unit B Topic 6.indd 219 08/01/2015 16:12 The endocrine Coordination system released Key into inuence terms t he only blood cer tain to travel organs ever ywhere in t he body; in t he ot hers body. affect Some many and control hormones cells and ! tissues Hormone secreted that the A by travels body tissue an in to or chemical messenger endocrine the blood stimulate stimulates gland all its t hroughout t he The organs in produce of secretory one or more cells organ responds to a Any t hat t hese respond target The organ for kidneys, hormones. specic stimulates t he t he hear t, liver lungs, and ADH blood to liver organs specic is have hormones receptors, are called glucagon’s target similar organ and to target t hose organs. t he described ADH. Adrenaline, secreted by t he adrenal kidneys glands are just t he long inuences distance many target organs. communication The location by Figure B.6.4.1 shows t he t he principle hormones. of some of t he major endocrine glands is summarised in B.6.4.2. thyroid a target above pituitary secretes The in that hormone. Figure Endocrine vessels that of T arget Adrenaline stimulates organ organs composed glucagon liver. synapses. An e.g. around cells gland kidney. body, target organ. Endocrine t he and t he gland gland cell molecules hormone into of parathyroid gland adrenal gland the blood Hormone in Hormone of the to a passes blood target to the travels pancreas blood out move cell testis Hormone receptor target interacts on cell the and with surface delivers ovaries (male) (female) protein of the its ‘message’ p Figure B.6.4.1 Long distance communication using p hormones Figure the glands Pituitary This ✔ Study by There the is a lot of endocrine information glands and about gland ner ves. ADH to assimilate so it is idea the to compile the information written as a table in the the The body main endocrine hormones are glands secreted described in the by and these text about in From has t he t he B.5.4 a size brain you ver y of a and g reen is already specic pea. It is situated connected to know t he target t hat organ: t he it by below blood pituitar y kidneys. t he vessels gland The and secretes pituitar y also and releases is a known, hor mone not t hat inuences sur pr isingly, as g rowt h g rowt h t hroughout hor mone (see t he t he case with suggested , page 223). in The activity. roles of control. a study all is whic h body good their positions they their gland hormones and The that gland hypot halamus tip B.6.4.2 features pituitar y hormones gland t hat stimulating is sometimes inuence hormone ot her (FSH) known glands. and as t he master Hormones luteinising like hormone gland as t hese are follicle t hat control (LH) it secretes t he 220 835292 CSEC HSB Unit B Topic 6.indd 220 08/01/2015 16:12 Coordination activities of and t he You can The pituitar y t he read t hyroid rate and Thyroid These is the gland gland t hat about also and the released The are in best under concentration of t he ovaries and t he system testes. a hormone of t hat t hyroxine inuences which t he controls activity our of metabolic glands the neck. known. It is The gland calcium thyroid responsible instr uctions parathyroid gametes: endocrine B.7 .3. release parathyroid glands in secretes its and is produce t his development. two B.5.5.5). organs more The our thyroxine and control for the releases ions and secretes for pituitar y a several growth gland hormone phosphate and that ions hormones, when helps in but metabolism the it to is cold (see regulate blood. Pancreas The pancreas enzymes Langerhans pancreas. (see is bot h a duct into are The t he cells an to These endocrine in t he are situated is our just above It stimulates t he hear t to beat and These describing t he know USA T estes ‘male t he kidneys hormone to release body’s in t he organ are t hat The secretes islets scattered and some in and t hat of t hroughout glucagon secrete has glucose, in blood ability into t he t he blood t he organs air ways all to This over widen, t he t he pressure. to an adrenaline. target respond to adrenaline danger r ush, or sometimes stomach’. adrenaline needed ovar ies are The hor mone’ One is known people t he case as carr y. of epinephrine. These severe deliver allergic You a may dose of reactions. of testes and In t he t hey t he fact, t he organs are secrete ovar ies bot h effects of t hat also make gametes endocr ine organs testosterone, secrete males and testosterone is to sexual sometimes oestrogen females for secreting known secrete increase called as bot h t he t he of t hese g rowt h of tissue. across not are hor mone’. secondar y stimulate t he whole sexual directly t he formation body. Bot h characteristics related to of gametes, hormones during reproduction puber ty. but but t hey stimulate which t he These are also have ot her development are features associated wit h t hat t he sexes. Table t he t hey insulin experienced t hat However, hormones effects two and an intestine. ovaries and hor mones. muscle pens hor mones. ‘female are and small secrete increase t he has Canada, t hey reproduction. steroid an ‘butteries ‘epi’ if and testes as and about liver increase Ever yone it adrenaline The faster changes excitement. of tissue islets ‘emergency ’ body. The organ t he glands hormone t he into B.5.4). Adrenal In endocrine travel B.6.4.1 ovar y lists t hese secretes promoting developments progesterone gestation – t he t hat which period of begin gets time its at puber ty. name when from women In its are addition, role in pregnant. 221 835292 CSEC HSB Unit B Topic 6.indd 221 08/01/2015 16:12 The endocrine Coordination system q T able by B.6.4.1 The testosterone Sex secondary and The ● Hair ● ● ● ● endocrine wit h t he around as t he processes need if to keep speed is a not There are target organs. q T able shoulders of (wider deepen The breasts hair vagina a reach is stimulated It of Roles of the armpits and on the face and and fuller grow its outer lips (labia) become more pronounced arms slower time target ‘cheaper’ of coordination for are t han are of t he two t hese are listed nervous hormones organs. and an not in to t hose be energy endocrine does not need since (see efcient working Table t hat up’ compared transpor ted t his ner ves, ‘charged systems system However, using neurones hormones the and hormones system in hips) longer develop the takes by e.g. grow longer , under t heir body, hips much much examples Some the to to grows of grows is begin begins the than to necessar y, B.6.4.2 parts begins complex many females mass voice system. It in The controlled instantaneously. other grow to and enlarge to system body males grow begins Hair ner vous t he on to increase W idening ● begins penis The ● of characteristics scrotum The Pubic ● and grows Broad ● The hair Muscles ● Females sexual testes Pubic ● characteristics control oestrogen Secondary ● Males sexual and to t here page matter happen is no 217). So alternative. toget her on t he same B.6.4.2. systems in controlling some body activities Body Heart activity Nervous rate speeds the Skeletal during muscle during contraction reex heart Endocrine nervous and system slows knee jerk speeds up Adrenaline stimulates rate stimulate muscles to to Impulses contraction (e.g. system Adrenaline down contract muscle a up Impulses exercise Skeletal system Autonomic stimulate muscles to open No arterioles (vasodilation) effect (would be too slow) contract reex) ✔ Exam tip Control of glucose concentration Adrenaline is the ‘ght or in No the effect Insulin blood store stimulates glucose glucagon ight’ convert hormone. answer, You but can put always this explain in body by for referring to liver cells to glycogen; stimulates glycogen to liver to glucose an what it Response dangerous means as preparing of the body to a Impulses situation travel eyes, legs, body for quickly heart to to prepare Adrenaline stimulates e.g. liver lungs, and organs, heart, the ‘ight or to ght’ prepare for ‘ight or ght’ action. responses responses Written Completing Use to the make The table information a table headings have nd a better more activity about recording for ideas your for endocrine all table the could headings. information. Also, organs information be the can use to this the this ones Remember you and in hormones book below, use the book about that although index and of other they secrete hormones. you the might book resources to to 222 835292 CSEC HSB Unit B Topic 6.indd 222 08/01/2015 16:12 Coordination nd not out at what all, that they 192 and q and control happens and also should ADH T able B.6.4.2 Hormone when what be. on The There page the hormones happens is 190 they you T able Effect organ(s) target where Hormones T arget are Transmission Effects can effects of is be be This is who t he he fail (HGH), of was which be is grow at about. referred to Michael and of Effect of excess systems system are or are is by nerve transmitted glands is by Response is impulses by receive neurones messages rapid always stimulated muscle fast boys and who was mass; family localised each to the cells neurone always short-lived, e.g. contraction the had one who problems to a d idn’t wit h t heir grow production of divided into did and a to wrong be human gland, t here nurse realised wit h growing. growt h him Children hormone alt hough Michael’s was took t hat in normal doses who quantities of HGH. dose rare cases and is of 0.3 usually to be t hat anyt hing measurements, parents did The being parents unlikely some Michael’s specialist, weekly smaller seem of reassured injections total not pituitar y later t he somet hing well. growt h secreting usual t he as rates and was deciency doctor years char ts t here just a by different prescribed t he He have reasons referred not realised t hree. Some some was specialist is Effects many secreted to worr y rst ot her children This Impulses the too of ten t he body nervous Transmission e.g. two about grow wit h The 188–189 deciency and Muscles growth parents may he blood slow grew stor y to begin t hat or quantities hormone. Michael’s To much, study enough t here the short-lasting; e.g. fast who in widespread, may pages Effect on Communication messages relatively boy when hormones transported The growt h endocrine Nervous receive long-lasting, Case the adrenaline Response are of system organs on very greater organ Comparison by far hormones T arget is in insulin Endocrine Communication secreted system use. gland B.6.4.3 Endocrine not secreted about can secreted q are are information which Comparing if endocrine some were tests right. to nd HGH. dosage is mg kg per injected based on body under mass. t he skin p Figure B.6.4.3 Michael and his parents t hrough t he increased. not In Justin’s at t hey were at about case rst it was An be is size t he to below must all. he his pleased bot h somet hing down Michael Alt hough worried were week. responded slightly at how average wrong Internet t his smaller treatment t han most of and his his growt h friends, he is all. opposite see to as – he much height. his search grew he was But growt h much. growing eventually did suggested too to not t hey seem t hem Justin’s parents especially to t hat be he as realised t hat slowing might have 223 835292 CSEC HSB Unit B Topic 6.indd 223 08/01/2015 16:12 The endocrine Coordination system a growt h much coarse t heir problem. and had facial who The specialist rare tumour treat for it decided wit h people used to died. That was treated brain (see available companies ageing prepared wit h from trading and use is scan Af ter tumour people t hat t heir same son, t hey specialist which in who jutted an are his him to he had a parents, rat her t he ver y Michael. t hat wit h too and took operation, which grew out as revealed discussion on pituitar y was t his is widely It is as ot her as t he t han options available to claim and it t hat it is t he order t hough a serious only UK, from HGH is had who modied However, USA who people developed genetically t he even people some children, by People increasing, of t hat available. such widely Internet. is glands discovered source countries, t he use t he it manufactured doctor. its for t he of jaws radiot herapy from and some a see brain t he from HGH 306) in a to gland. when HGH Now page effects or feet, control tumours. stopped legally prescription for remove t hese be disease. bacteria to and frightened him pituitar y medicines wit h HGH were Ver y Justin his descriptions hands referred sent in found large features. doctor specialist They ver y and on foreign has anti- illegal. Questions 1 Children check 2 to When 1 1 kg. grow nd out Michael What at his rates. Michael t he growing of a growt h too HGH specialist slowly? injections he was dose? Suggest 4 Suggest the advantages of having a safe form of HGH widely available. 5 Suggest cosmetic dangers reasons can was would programme weekly tumour How 3 t he a t hat star ted was how different of such be taking as responsible a natural for Justin’s hormone condition. like HGH for Name the anti-ageing. Questions 1 State 2 a the Explain organ 3 function The for pancreas enzymes in is reach 4 Adrenaline 5 State three 6 What will is and secretes Name which endocrine meant glucagon digestion. way what of the the the for two digestive the a term c and ‘fight or between person’s and and their flight’ target several of the how target is if and b organs of enzymes enzymes. this target adrenaline. for How different do from the organs? hormone. nervous reflexes organ. five three system reach target List hormones hormones differences to the ADH. hormones called happen by glands. Suggest hormonal he/she has why this is so. coordination. been drinking alcohol? 224 835292 CSEC HSB Unit B Topic 6.indd 224 08/01/2015 16:12 Coordination and control B.6.5 Types of Sense organs Types receptor Learning By the end should A stimulus is any change in our external or internal environment. to stimuli from changes in our surroundings – t hese are outcomes of – and changes already discussed inside t he body – t hese are internal of t he internal stimuli in Unit stimuli. B.5, such We blood temperature (see pages appreciate as t hat B.6.5.1 t hey shows t he list different sense organs in t he body and t he stimuli stimuli sense ● state that organs the they and the names detect of the detect. B.6.5.1 The sense organs and the stimuli that they describe organ in the the eyes role of detect a Sense body internal 197–200). ● T able the both external the receptors q that to changes stimuli Table you have ● in topic to: external and some this able responds stimuli receptor We ● respond be of number of different Stimulus receptors. ● Eye ● Ear ● ● ● Nose ● T ongue ● Skin ● ● ● Function Sense cells Most in organs conver t eye your (brightness) and wavelength (colour) Gravity Motion Smell – chemicals in the T aste – chemicals in solution T emperature air changes T ouch Pressure Pain receptor only respond when intensity Sound energy cells – receptor contain will eyes a t he receptor t he on of Light of cells to pressure are t hat stimulus respond to t hey t he closed one detect into stimuli. t he specic as well as to appreciate To energy stimulus, light. Just t his. do of tr y a t his, ner ve receptor impulse. alt hough pressing Receptors t he cells gently only send p Figure B.6.5.1 responses impulses if t he stimulus t hreshold level. stimuli which to Table is above B.6.5.2 each is a cer tain summarises intensity. t he main This intensity receptors and is can How you many see stimuli and here? t he shows t he sensitive. Key terms ! q T able B.6.5.2 Stimuli detected by body receptors Receptor Stimulus Receptor A cell specialised to Location detect a specic stimulus. External Stimulus Sound Sound-sensitive cells Inner A environment Light Rod and cone cells Retina of the Smell Chemoreceptors Nose T aste Chemoreceptors Nose T emperature Heat-sensitive Dermis Pressure Pressure-sensitive T ouch T ouch-sensitive Pain Pain-sensitive Gravity Gravity-sensitive cells cells cells cells and of is in the detected in the by a body. tongue the skin Dermis of the skin Dermis of the skin Dermis of the skin Inner that eye receptor cells change ear ear Internal Blood concentration Osmoreceptors Hypothalamus Blood temperature T emperature Hypothalamus T ension in muscles and receptors Proprioceptors Muscles and tendons tendons 225 835292 CSEC HSB Unit B Topic 6.indd 225 08/01/2015 16:12 Types of Coordination receptor Written Frightened Make a sense out drawing organs T ables B.6.5.1 Figure touch, in B.6.5.2 pain, touch your skin! to that annotate and control activity similar and Receptors In of and B.6.5.2 the you pressure in Figure it with notes to help you. B.6.5.1 on to how show the the stimuli location are of the detected. Use skin can see and receptors in t he skin t hat are sensitive to temperature. temperature receptor receptor epidermis free nerve ending – pain cold receptor dermis pressure receptor p Figure B.6.5.2 Receptors Olfactory receptors Olfactor y receptors contain lining t his ability quite cells to t he to found skin in t he detect chemicals cavity. These give taste. If you That is chemicals tongue sensory the t hat bland. different are in only have a because t hat us t he give respond to our ver y sense bad cavity to tastes have of cold receptors avour ve nasal which smell you in our (see (Figure B.6.5.3). dissolved and will t he also know nose food, in t he help t hat t he wit h food respond whereas They mucus to our tastes many taste buds on below). neurones brain supporting sensory cell cells mucus hairs to p Figure B.6.5.3 Olfactory receptors (sensitive to – sensitive chemicals smells) 226 835292 CSEC HSB Unit B Topic 6.indd 226 08/01/2015 16:12 Coordination T aste Taste and control Types receptors receptor taste cells are found in groups, called taste buds, in the of receptor pore epidermis taste of the tongue chemicals, mouths. (Figure in this B.6.5.4). case Individual those taste Like that olfactor y are receptor receptors, dissolved cells are in the located in they saliva detect lining specic of hairs saliva dissolved our regions of sensory cell the tongue as shown in Figure B.6.5.5. They respond to only one of epidermis the of following as stimuli: sweet, sour, salt, bitter and savour y (also tongue known umami). supporting Practical Detecting different cell Activity tastes: a blind sensory neurones to brain Figure B.6.5.4 A taste test p bud Requirements 3 ● 0.6% sodium chloride ● 4.0% sucrose ● 0.4% citric ● 0.5% solution solution solution ● 250 cm ● paper ● 100 ● paper ● 10 beakers or measuring cups cups 3 acid solution of Angostura bitters cm measuring cylinders towels 3 or other ● stirring ● balance In this bitter rod (measuring investigation sour, salt collect your own Divide the ● into tastes cm measuring cylinders or syringes sweet, 1 substance you and will results. four 0.1 bitter. chloride – your thresholds through this before Each group salt and weigh cotton ● nd Do sour, g) Read groups. sweet, Sodium to should 0.6 g as for four different instructions starting bitter, out the swabs the and tastes: make a table to activity. make up solutions of one of follows. and place in a beaker and add 3 100 cm of tap water. 3 ● Sucrose tap – weigh out 4 g and place in a beaker and add 100 cm of 100 cm water. 3 ● Citric acid – weigh out 0.4 g and place in a beaker and add 3 of tap water (alternatively place 3 cm of vinegar in a beaker and add 3 97 cm of tap water to make a 3% solution). 3 ● Bitters – place 0.5 cm of Angostura bitters into a beaker and add 3 95.5 2 Stir all cm the tap water. solutions and then dilute them as follows. 3 ● Transfer 10 cm of add 90 the solution you have made into a second beaker 3 or cup than and the original cm of water and stir. The concentration is 10x less solution. 3 ● Transfer 10 cm of this second solution into a third beaker or cup and than the 3 add 90 original ● 4 Hand 10 your five etc. the labelling are your The this less and a to than solutions solutions now own water doing 000x B5, Y ou of stir. The concentration is 100x less solution. Continue and 3 cm secret ready results make the to a that more responsible labelled so two concentrations that are 1000x original. ‘1’ you should can to do the testing. and do not share all person be do When them the a ‘blind you until to label lowest. test’ taste as of has to A5, should the each everyone A1 They B1 to keep solutions. solution, record finished. 227 835292 CSEC HSB Unit B Topic 6.indd 227 08/01/2015 16:12 Types of Coordination receptor 5 Rinse your paper 6 Dip a mouth with tap water and wipe your tongue dry and with a control clean towel. clean cotton swab into the lowest concentration of one of the four bitter sets can if of you and taste put ruos ruos beginning 7 Enter all lowest 8 starting sweet & is only fair Figure B.6.5.5 at ticks, the the your tasting your with a to results results one idea not to is a put what cross. with and swab sure a a Rinse clean cross. start around it on is, out cotton If you the your put a your have in If you of you table, with some recognise identified set If your mouth swab. next tongue. tick the solutions, taste, again concentration. on a of class each with to data taste this the you table or that you else and everyone which do compare cotton not put A2 taste lowest the good way if the are are activity most by thresholds to spreadsheet could put detect the and and find the identify. solutions in order sensitive. testing taste the solutions is to calculate how to do ‘blind’? the The molarities salt of p it two you anything try what Smear but concentration Discuss Why A1. taste then remember sweet e.g. anything, cannot water the tubes, taste T aste regions on the solutions. Y ou may be able to research this. the tongue Tr y this Location of yourself taste receptors on the tongue Requirements ● 5% ● 0.5% ● 2% ● 0.5% or One 1 sucrose citric sodium other person the that divide 3 Put the 4 Choose a liquid the the the whether they tick cross a Repeat for time Choose second When four you and the a ● cotton ● a copies cup Do beakers the four to contain tastes water swabs blindfold other of of or of is the Figure not subject. B.6.5.5 include including the names the of lines the in one the at of other five taste with the which taste regions and regions appropriate allowing mouth random the subject identify the their water. subject. of the subject and repeat not. region to it is. the tongue the cotton tongue The Record on wash a the taste or the put of out test, outline a their result the in Figure should by say placing a drawing. fresh mouth recording into shown subject the using swab as the cotton swab between results tastings. on the drawing. completed look ● the regions. out tastes to tell another B.6.5.5. it can the have four into rinse the not outline tastes, Figure to on of Do each tongue apply B.6.5.5. or make and cups solutions outlines. blindfold one bitters experimenter subject and solution Angostura to paper the substance subject on Ask 6 is Ask 2 of bitter 4 ● solution chloride solution tastes 5 solution acid at your Evaluate tasting result the and the see ve if regions they investigation and of the tongue with conrm the information discuss the results. the in 228 835292 CSEC HSB Unit B Topic 6.indd 228 08/01/2015 16:12 Coordination and control The eye Questions 1 The skin 2 Where touch is in the body List six 4 Which 5 Impulses internal part of the from a receptors Name impulses are name c B.6.6 you body the different expect stimuli. to find State the four highest of these. concentration of type to the the body responds to receptors of b gravity? and neurone brain. detects. taste that Name receptors transmits the part of are nerve the carried impulses brain where to the from these received. is given changes The which olfactory these and several would stimuli brain. What to receptors? 3 6 sensitive in to receptors blood that detect a light, b cooking odours, concentration. eye Learning By The the end eye is situated in a bony socket of t he skull, called an orbit, and number of muscles attached to it so t hat it can be moved. The be this able topic you to: has ● a of eyes should Each outcomes describe the structure of the eyelids eye and eyelashes help to protect t he eye from damage by foreign par ticles. ● Tears produced by tear enzyme lysozyme shows horizontal a t hat glands breaks labelled wash t he down section surface t he cell of walls t hrough t he t he of eye and bacteria. eye. contain Figure t he relate the of eye the internal to their structures functions B.6.6.1 ● explain how images are formed scleroid ● choroid external eye suspensory explain the role of the retina. muscle ligaments iris retina cornea pupil yellow lens spot (fovea) aqueous humour conjunctiva ciliary muscle ciliary body in blind p Figure spot p vitreous B.6.6.1 A humour horizontal section optic through the human nerve Figure section B.6.6.2 through A photograph the human of a eye eye 229 835292 CSEC HSB Unit B Topic 6.indd 229 08/01/2015 16:12 The q Coordination eye T able Part of B.6.6.1 the T able eye summarising the functions of parts of the Description Function Thick Protection Choroid Dark layer pigmented layer behind the retina Prevents Supplies Retina Layer of behind Fovea (yellow spot) nerve Vitreous Ciliary humour in cells nerve the sensory Jelly-like ciliary in of (rods and cones) Light against internal the light proof reection retina sensitive damage; cells with nutrients and oxygen and removes waste layer tissue retina consisting only Cones only respond in bright light and detect colour cones Large muscle layer Depression of Optic receptor a control eye Scleroid brous and Thin nerve Sensory material muscle in a ‘hoop’ around the lens neurones Maintains the Contracts to Holds lens transmit shape allow of impulses the lens to from the retina to the brain eye get ‘fatter’ for near vision body Suspensory ligaments Strong Iris brous Circular pupil and in tissue pigmented the radial diameter centre; muscle of Pupil No Cornea Transparent the structure – structure contains bres to with the Controls the Crystalline elastic Aqueous humour Thin, Study ✔ The section change just a hole in the in iris Allows light Greatest structure surrounded by an the fovea and are in same the the as B.6.6.1 it blind has layer will conrm if you do into for the amount 60% of the focusing eye of lens refraction (bending) of light occurs as it moves into the focusing focusing Maintains of cells is light onto the retina to give sharp images; 40% of focussing Protects this the the shape of the eye cornea yourself a They plane your blind spot Requirements as ● you entering in both spot. horizontal Used liquid transparent Tr y Figure light involved the tissue tip section of is pupil Finding horizontal amount and membrane Transparent Conjunctiva place circular cornea; Lens the in this A cross and a dot on a piece of card – they should look like this: rst activity. + When you (yellow look directly at an object, the image of that object is on your fovea spot). 1 Hold 2 Close be • the card your able to left see eye the card the and Bring 4 Repeat with the other 5 Repeat with the dot 6 Hold the 7 What do card closer and to stare at right the of the cross cross with the at arm’s right length. eye. Y ou should your face. What do you observe? eye. on the left so that investigations the the towards vertically these spot dot dot. 3 blind the with fovea? of the tell Look the dot you at cross. is above about Figure the the cross relative B.6.6.1 and and repeat. positions its caption of for the a hint. 230 835292 CSEC HSB Unit B Topic 6.indd 230 08/01/2015 16:12 Coordination Control and of control light The entering the eye Dim light Bright eye light The iris gives us our ‘eye colour’. It contains involuntar y muscle arranged 1 in two layers: radial and circular. Like the pair of skeletal muscles in the arm 2 these muscles act as an antagonistic pair in each iris. They control the size of the pupil in response to the amount of light entering the eye (Figure B.6.6.3). 1 Circular muscle 1 relaxed 2 Tr y this Radial the muscle contracted muscle 2 Radial muscle contracted relaxed Pupil Pupil yourself dilated (large) Watching Circular pupil constricted (small) reflex p Figure eye to B.6.6.3 dim and Responses bright of the light Requirements a ● It is 1 small best If 2 to you right mirror, be are in left handed Carefully Label your B.6.6.1 4 to Position cover 5 with the of Cranial or front make in of a try a torch this. front your or of your left eye. drawing right to show you have eye. the If eye you are and identify so that both lamp or into torch. to to the structures drawn (use Figure is hands. to hold your After record it After your the few to 15 your face. seconds Shut your eyes and remove your hands and eyes. torch eyes. a what close so Look that into seconds happens to it the turn your illuminates your face mirror then turn the eyes and lamp and off again. write an without on Make explanation reex two The response cord you mirror in and when lamp observations. The reex. eye happens directly these the mirror a ● you). mirror Arrange lamp room hold the your help the drawings paper features. what the The handed drawing them and darkened hold observe shining a study surrounding 3 pencil reexes In of t his before t hat t he case going stimulus is you iris t he to t he learnt to dim and impulses t he about on pages bright are sent light to t he 212–13 is an were spinal example brain rat her of a t han reexes. crani al t he effector. light intensity. Rods and cones are t he receptors ✔ Study in Light is to both be considered which send impulses to t he brain via sensor y neurones. Radial muscles motor neurones light). The Image Light rays. and is are enter of iris are contract in t he our to eyes. (bent) to are small able focused sent retina and change made refracted are t he t he effectors (radial diameter in of which dim t he light pupil is receive and t he impulses circular in physicists particles and to be waves. called You from rays to of consider light that what enter happens the to eye. bright response. formation We being in by of or need circular made t he photons retina tip spinal t he to par ticles see objects When mainly form an cerebr um imperfect. light by The ( photons) if t he rays t he rays from cornea image of light on t he brain. focusing t hat an and In fact, t he a straight rebound enter lens. As turns in t hem, object t he retina. process travel strike t he This result, images t hem eye leads lines off t hey to ner vous t hat upside called t hem t he are rays impulses form down on t he and 231 835292 CSEC HSB Unit B Topic 6.indd 231 08/01/2015 16:12 The Coordination eye back-to-front and t he cerebr um inter prets right around light on way rays the str ucture t he and light rays from the of images, lling refract in t he (bend) aqueous t he retina turning as ‘holes’ they humour into leaves t hem as t he best ‘holes’ right it can in way and t hem. up (Figure control The and t he B.6.6.4). pass the lens focus light retina reflects person all the light rays within in off the all these directions two enter light rays (bend) the image is inverted (upside down) and p 4 interprets Figure the image B.6.6.4 the right Focusing way by eye refract as they pass from air into the the brain the cornea up the eye c m pinhole Tr y this yourself Inverted image – it’s an upside down world Requirements 6 cm ● a piece of suitable polystyrene material) cut (or to other a ● the piece stuck of to card the with a pinhole polystyrene block or m c 3 dimensions 3 c in Figure held in place with an elastic band B.6.6.5. m 1-2 cm thick p shown Figure 1 Hold the face. Now apparatus point close the to one apparatus of your towards eyes with the somewhere card which touching is your brightly lit B.6.6.5 2 and look you see. Turn the 3 of until a Explain pin-head the you casting about the apparatus base hole is the at a around block see to your get so against the shadow little through pin on this the is cheek Y ou will Describe Describe closest bone. silhouetted eye. effect. pin-hole. pin your head your the to you, Look against have and to and not record the through the hole. move the record what by cornea, what card. the The Hold pin pin head apparatus you see. observations. Accommodation Alt hough t hat can lens is taut t he most of change t he its surrounded elastic ligaments t hicker are is by an pulled slack, shape. bending shape Thick elastic and t hen of light allowing lenses is to done focus membrane. t he t he us lens elastic refract has a If t he more and shape. recoils t han If and t hin it distant suspensor y t hinner membrane light t he near is t he lens objects. The ligaments t he t he are suspensor y lens has a lenses. 232 835292 CSEC HSB Unit B Topic 6.indd 232 08/01/2015 16:12 Coordination When and looking control at a The near object t he light rays are diverging when t hey the enter ciliary muscle t he eye. We t herefore need a t hicker lens to refract t he light to give a shar p distant relaxes object the focus on t he retina. The ciliar y muscle shown in Figure B.6.6.1 can suspensory contract ligaments reducing wall of t he directly When t he eye to t he tension forms t he in a t he suspensor y ‘hoop’ around ligaments. t he lens. The Notice ciliar y t hat it muscle is not in pulled t he attached muscle relaxes t he pressure inside t he vitreous humour the t he it This is t hin. When t he suspensor y is suitable ciliar y ligaments for muscle increasing looking contracts at far t his t he objects counters tension – t he t he on eye is pressure t he far lens adapted. inside t he reduces t he tension in t he suspensor y ligaments so t hey become side view of elastic near membrane objects – t he eye recoils is near and t he lens is now suitable for is thin eye front view of eye eye Figure B.6.6.6 A far adapted eye slack. (unaccommodated The lens pulled so p and are tight lens. ciliar y stretches eye looking for distance vision) at adapted. the near by ciliary muscle object contracts Figure B.6.6.6 objects are B.6.6.7 shows shows focused an on unaccommodated retina, but near accommodated t he eye in eye; in t his objects are condition out of distant focus. Figure the suspensory ligaments an which near objects are focused are on slackened t he retina, but distant objects are out of focus. the Written activity lens is allowed to bulge Completing This a exercise side view of eye p Figure front is designed to help you remember what happens when Use the T able q your of eye B.6.6.7 A focus from information in a far object Figures to B.6.6.6 a near and object B.6.6.7 or to vice help near adapted eye you (accommodated change view table for close vision) versa. you to complete B.6.6.2. T able B.6.6.2 Comparing a far Feature Distance Ciliary Far of focused object eye adapted with a near eye adapted Near eye adapted eye far muscle Suspensory Lens adapted contracts ligaments taut shape Focal length Retina The retina sensitive Rods rods, an is t he cells function is broken impulse conditions (called light-sensitive called in dim down passing it d ark rods takes some is Cones only function by dim It only blue, to colours, is of t he as shown Rhodopsin, brain. time even When before t he in eye and in contains Figure t he light-sensitive low intensity a person t hey rhodopsin can t hat goes see light- pigment light, from clearly. was t he B.6.6.8. fully in resulting light to During t his bleached in dark by time t he resynt hesised. light colour. t he ad aptation), light down light. par t cones (bleached) to bright detecting and than light. red or bright They thought depending in rods. that green on light Iodopsin, are found there are light. the type as they the mainly three The and have a pigment in the types brain ratio of higher in fovea cone, inter prets of the threshold cones, and each the cones is not allow us being impulses that are for broken to see sensitive as different stimulated. 233 835292 CSEC HSB Unit B Topic 6.indd 233 08/01/2015 16:12 The Coordination eye Figure choroid B.6.6.8 shows a number of interesting features of t he and retina. control First, pigmented note t hat light must pass t hrough t he neurones before it stimulates t he rods epithelium and cones. receptor Note also neurones. t he way Several in rods which rods synapse and wit h a cones single form synapses receptor wit h neurone. receptor This makes t he retina more t hat can distinguished sensitive to dim light, but reduces t he detail element In be contrast, each cone in such synapses light. wit h a single receptor neurone. This impulses are cone mitochondria rods enables down The t he different fovea own retina image from plane as spot) neurone t he distribution distinguish receptor (yellow sensor y to of Figure neurones is to centre rods detail of and from composed t he brain. our t he is eld. across t he clearly as different entirely This visual cones more of why par ts cones. we Figure retina get Each t he B.6.6.10 in of t he cone most sent image. has its detailed shows t he t he same horizontal greater t han if B.6.6.1. synapse Stereoscopic cell bipolar body vision of neurone Because single we eye. have More two eyes, our impor tantly, eld of vision because t he is elds of vision of we t he had two a eyes synapse overlap, cell body nerve nerve light p rays Figure from B.6.6.8 front of eyes of (Figure what we see B.6.6.9). is This registered is known at as a slightly different stereoscopic vision angle and by enables cell our axon direction much of bot h optic brains to judge dept h of eld (3-D effect). of impulses eye Section through the retina 150° 150° fi e ld p Figure B.6.6.9 Tr y Human this Peripheral field o f of bin o cu ar vi io s n stereoscopic vision yourself vision Requirements ● a set When the of you fovea. This is coloured look straight Everything your Hold a 2 Look straight your red pencil face. the your image eld of of protractor any vision object falls in front of you on the rest of length just behind falls the on retina. vision. in ahead Keep in a ● ahead else peripheral 1 of pencils your and right hand move looking your straight at arm’s arm very ahead slowly while you towards do this. your the back. front Stop 234 835292 CSEC HSB Unit B Topic 6.indd 234 08/01/2015 16:12 Coordination moving and your peripheral 3 Use 4 the hand you) aware of the Try when protractor of your The you are aware of the colour of the pencil in eye your vision. ahead Repeat 5 control with and red to find the the angle position of between your hand your line when of you vision first (straight became colour. other colours, e.g. yellow, green, blue and purple. Record all results. this investigation between colours? the results the retina. using with Are your other there people. any Are there differences knowledge of the any between distribution differences people? of rods Explain and cones in 180 000 160 000 A srotpecer retemillim 140 000 120 000 100 000 60 000 rep rebmun erauqs fo 80 000 40 000 20 000 0 B distance p Figure the B.6.6.10 retina in the The distribution same plane as and across the retina abundance Figure of receptor cells across B.6.6.1 Questions 1 State the 2 State the focus on 3 State the 4 Where 5 Describe book 6 Explain 7 Look A the muscles name of the muscle near two the in the eye B. b c on you at of in sensory does detail why in the the iris that eye cause which the pupil contracts to when dilate. you object. types focus closely and arrows. of of a in to name the what a Figure the Describe happens at see in the of in the the far and the the retina. amount eye end colour B.6.6.10 parts how in greatest person cannot Name cell in of a of when the very B.6.6.1. retina peripheral bending a you look light up occur? from a room. dimly Name indicated retina of room. the receptor the red and from the central by differs lit cells black part retina. 235 835292 CSEC HSB Unit B Topic 6.indd 235 08/01/2015 16:12 Eye Coordination defects Learning By the end should ● be B.6.7 outcomes of this able describe topic Eye and control t he size defects you Defects of The of the eye to: the causes of ability t he lens to focus images on t he retina is affected by t he to eye of t he eyeball, t he shape of t he lens and t he ability of lens change defects shape. ● list ● some discuss defects how eye of the eye defects clearly. ● any Two of of t hese t hese factors defects change are long adversely, sight and t he eye shor t will not focus images sight. can Long be If sight corrected describe cataract the and conditions Long of sight enough. glaucoma. t he retina, t hey be are is focus As t he sight while seen corrected lenses. caused Long as by by having results t hose in from using a as light shows, rays eyeball, from objects you converging B.6.7 .2b diverging shor t near out-of-focus Figure a images see a lens lens, in is behind t he onto convex focused t he This light t he not being spectacles refract object t hat objects B.6.7 .2a. lens will near a focused Figure (convex) t he from are in or distant retina, defect or on so can contact sufciently to retina. a lens curvature enough or is not eyeball great too short near objects are focused b behind overcome (convex) by converging be p Figure are B.6.7.1 used by T est frames like ophthalmologists these to Figure Short sight Shor t sight correct strength of the lens Long caused sight by and b) having its an and on far objects the can retina correction is too convex. Shor t eyeball sighted people t hat are is too able long to or focus a lens images from for near each is a) near focused find whic h the B.6.7.2 retina lenses both p the objects on t he retina, but t hose from dist ant objects are focused eye in front of in Figure lens focused retina, B.6.7.3a. (concave) t he t he lens in so This defect spect acles diverges t he onto retina. t he t hey light are seen can or rays be as cor rected cont act from out-of-focus a lenses. far by As object as using Figure and you a can see diverging B.6.7.3b allows shows, t hem to be 236 835292 CSEC HSB Unit B Topic 6.indd 236 08/01/2015 16:12 Coordination and control Eye defects a lens curvature eyeball too is too great or long far objects front of are the focused in retina b overcome by (concave) lenses diverging both be p Figure q T able T ype of B.6.7.3 B.6.7.1 a) Short T able sight Near in objects from the are Older in of a people bifocal objects the can retina correction and short sight the be seen cannot be Converging clearly diverging lenses (convex) light refracted cannot them as are the be seen parallel refracted focused on the clearly light too Diverging in lenses (concave) rays much so retina (presbyopia) age it as them focus not far on retina objects from t he its long cannot focus onto Far leaving b) and Treatment sharp sharp Over comparing rays Short sight and Cause Long Old sight near focused 40, t he elasticity more-or-less generally lenses for xed use of t he shape spectacles lens is gradually suitable t hat only have a for single lost, eventually distance vision. converging lens or reading. Astigmatism Astigmatism par t focuses occurs t he light enough. Usually be to tted can be Cataracts (Figure t he too most counteract used Cataracts if to correct and of cornea much, t he t his or lens but image uneven has an anot her seen is uneven par t out cur vature. of does cur vature. not focus. focus Special Spectacles or If t he so, light lenses contact one must lenses astigmatism. glaucoma occur B.6.7 .5), when t he especially lens if becomes t here has opaque been a lot or of milky wit h exposure age to ultraviolet p Figure B.6.7.5 cataract light. Lef t untreated, people will go blind. It is an easy condition to in their This person right has a eye treat 237 835292 CSEC HSB Unit B Topic 6.indd 237 08/01/2015 16:12 Eye Coordination defects and may born be wit h done by cataracts replacing in one or wit h bot h an ar ticial eyes. They lens. may Some also and children need control are replacement lenses. Glaucoma Glaucoma t he blood star t to t hose not is die; rst from drain unaware vision. t he result vessels t he t hose fovea. properly. of t he Some and uids is glaucoma a p Figure B.6.7.4 A ophthalmoscope slit-lamp ver y to t he is r un a It t he peripher y it can of in t he because develops slow eyeball Neurones increases wit h water y. be t heir eyes treated in in t heir later eye are do of ten peripheral have dr ugs ner ve t he people of ten wit h and uids and deterioration and obstr ucts optic retina t he slowly t hat t he to a cloudy improve eye. in families, children beam to t here in ner ve. usually born t he young ne opht halmologist supply as pressure optic pressure are from t hat shines t he Glaucoma are tends impor tant B.6.7 .4 t hat changes drainage As increased The children appearance of of supplying of explore are light t he and tested into spot is t he symptomless for it. eye. where The as beam develops, instr ument Magnifying t he it falls in lenses and it Figure allow an t herefore eye examination nd out if Case Train t here are any signs of early disease. study of hope Khali Bhai, t hree of aged t he surgeons 10, many Sunita, aged t housands working on t he of 15, and Rojdi patients Lifeline to aged have over been 90 are treated just by Express. The Lifeline Express is a state-of-the-art hospital train that travels across India providing health care for thousands of poor people. On board the hospital train are volunteer surgeons who operate on people of all ages, including many children who had polio when they were younger, have cleft lips (see page 266) and have hearing difculties. The elderly are not forgotten: many operations are carried out on people like Rojdi who have p Figure B.6.7.6 Khali Bhai, disabled ver y limited sight because of the cataracts they have in one, or both, eyes. since to birth, have an is carried by her father operation on the Lifeline There Express parked in Biaro Pradesh in central India in are many cases of hearing loss in India. Children for most of t hose can even be life-t hreatening. younger t han Madhya 14 years cases, people ear account infections only have infections Sunita an old ear was studies. No one of have received her nor is in her proper t here t here The offers possibility poor districts Sunita’s will who up for Sunita bat he had led family in. to took even if a This can damaged her to a had loss ear was or In extreme reason severe t he is t hat chances hearing dr um and clinic it loss. The increases cause hearing t hey hearing as t he affected hospital unlikely result her in she of loss. of school t he early would treatment. are no specialists was has treatment a in equipment Express of would lost to untreated, This and Lifeline operation make lef t specialist available. t he if t hose. infection district, (ENT), of water infection. days In t he which, one untreated dir ty wit h not modern by and nose t he have her and t hroat hospital up-to-date surger y ot her wise success ear, in to to hopes surger y one were equipment people access fat her if in remote t hese t hat and and facilities. at school she time. 238 835292 CSEC HSB Unit B Topic 6.indd 238 08/01/2015 16:12 Coordination The and Lifeline Express more t han acute scarcity because abroad of t his China 600 100 000 of Eye has completed Indians, facilities 000 have means it who and surgeons volunteered project and control medical and to been on projects live in copied train in for ot her far, beneting areas This personnel t he so r ural specialists. medical work has many mostly and has from defects face been across not hing. possible India The countries, an and success such as Zimbabwe. Questions p 1 What is a Figure B.6.7.7 operating 2 What are t he benets of cataract Express. operations? operate 3 What are t he dangers of hearing loss for poor children only have access to ver y limited healt h care table lies The to inside on surgeon remove the an is his Lifeline about to cataracts and whose insert families Rojdi cataract? facilities in plastic lenses t heir region? 4 5 What ot her ot her t han Polio has been operations 6 India staff. ways using has for t hose t he do visited India. How treatment t here effects well t hey by can t he it to from of to Lifeline solved to t he like healt h t he India. care to Lifeline Why do ver y poor people Express? children need polio? equipped want be available deliver trains eradicated many Rarely are hospital hospitals work in Express. so t he and poor, This well qualied remote districts problem poor can receive each is not medical like unique proper to medical rich? Questions Talk about ? 1 Identify three 2 Explain the eye defects and state how eye tests for one is corrected. Inequalities importance of young The case Lifeline great Summary Humans have endocrine ● The two coordination (hormonal) nervous system systems: the nervous system and the to divided into the central nervous system (CNS) and the peripheral the CNS; nerve no ● are the cerebrum main ● ● cerebellum medulla blood ● The control and the which spinal and nerves the form functions, over nervous spinal the PNS. which system cord controls higher rich and for others there in are India the how to poor. the in with facilities next provide facilities available nothing Discuss countries poorest in Discuss this for the should very The we society. have (ANS). family which provision that the form brain: functions and with your friends, teachers. of memory controls many aspects of homeostasis, metabolism controls which brain autonomic the and and The body hemispheres) growth oblongata the control of vision which (PNS). out highlights movements, controls balance breathing, and heart posture rate and pressure. pituitary secretes form (cerebral reproduction, that parts hearing, hypothalamus system nerves PNS control, four thought, ● cranial in conscious There ● the cells nervous points study Express available with the provision state-of-the-art system. is health inequalities health ● in children. gland is hormones, the testes situated such and as immediately ADH ovaries, to and below control growth the the hypothalamus kidney, FSH and and LH to hormones. 239 835292 CSEC HSB Unit B Topic 6.indd 239 08/01/2015 16:12 Eye Coordination defects ● ● A neurone is impulses from the Nerves are bundles Motor nerves and Neurones all Impulses There pairs are the spinal how cord motor neurones of spinal the the insulated A in stimulus reflex thinking or is grey matter a the reflex, and are the brain, the actions to bring movement The ● sense skin ● eye ● ear ● ● – – – sound, – taste sense impulses cells back for detect the centre the brain of The eye the eye are Most called another using between of motor up or same reflex, are spinal and the the centres The to the reflexes through muscles transmission of impulses which they the brain. length respond hand the reflex brain. of occurs. the along The through in flow A is diameter to and making spinal body as goes thinking cord. without the the pathway where – that in myelin. internal. response. changes where part spinal or cord the current not nerve any automatically the cord, the so and neurones external stimulus attached central of down either are without consists sections matter The in decision pain nerves nerves. happens spinal the stimuli touch, of iris of Impulses that involves the neurone. are: pressure movement are and of gives rods that that contract light and the light. are are All high cells size are not and send cells for are focusing the iris for do has in a to the light. the so damaged. In at not colour vision the fovea neurone vision at to is brain. This diaphragm light, pupil retina Peripheral neurone The the and cells cone resolution. bright of in receptor Each same In cells intensity responsible the (40%). eye. the low cones. the stimuli Receptor stimuli. of structures lens detect CNS. sensitive light very the reduce sensitive light share has enters to a that the Cones vision fovea light the blue many to specific detect as (60%) of air). cells neurones colours. field solution) the receptor Rods green organ in in the an the and cells eye. the cornea and to are Cross grey neurones painful jerk spinal which results action. detection between so is has rod red, detailed in a through boost (chemicals the the less amount of impulses the result the sensory and of discriminate the neurones cord. central spinal because (chemicals organ along specialised by and gravity smell and neurones. synapses spinal the made (focusing) the to temperature, nose the sensory nerves light – Cone glands. Most motor neurones neurones contain neurone also where into response through the ions one are the the to knee neurones organs tongue Each not about of from matter always reflexes are motor only between environment, through accommodation contract the The pupil along points white the goes although and neurones. and sensory motor nerves. There pass response the Voluntary the transmit in harm. cranial nerves gaps along matter stimulus pathway, impulses: CNS; muscles sensory gaps through is that fast against and out change is at Blinking, travel ● a nerves neurones myelin is withdrawal arc, cord action protected made pass grey – motor mixed small these the control cells. spinal sensory both substances. muscle of Sensory are The to effectors contain nerves, cross and to contain cells. neurones Around ● spinal nerve CNS only electrical receptors neurones. they transmitter show ● and are of nerves chemical of ● transmits transmit synapses. ● that sensory cranial, ● cell from mixed ● nerve impulses neurones. ● a transmit and is done controls circular the muscles less light enters dim light the to radial 240 835292 CSEC HSB Unit B Topic 6.indd 240 08/01/2015 16:12 Coordination and muscles the ● eye An in to image they way ● the is through eyeball. on an ciliary too with or retina. a The may for are to improve main the ● thyroid to see. The being light more light refracted rays cross this image interprets are as The far lens because a around hoop the so converge Short convex. the too enters (bent) to as give the the lens, the an right a sight caused The the is light diverging which same is the inside to the which the head, by more. that The an This slacken. much lens retina. rays eye by contracts. light or the with in close ligaments short the thin pressure behind cornea eye the refracting is pulled something suspensory that adapted, is of at corrected the When looking thicker, with ages Left by of an is not problem eyeball converge in is that front of lenses. is uneven way. It is and does corrected not with of FSH and growth be with by will go replacing cataracts to in pressure for The one or the so making blind. with both It an is it an artificial eyes. They the It eye because causes can be the neurones treated with in drugs eye. system ADH for controlling hormone in pressure blindness. from releases LH cloudy, people done properly. lead endocrine which becomes untreated, increase fluids the it lenses. away can and may born gland which and which releases also gland of adrenal which glands to are: controlling gamete stimulates blood to water absorption production growth in in in ovaries many parts of which the ovaries eggs they release rate to it that phosphate to blood controls hormone that stimulates widen and a and adrenaline activity; airways heart which glucagon testes and the ions that growth and rate in the stimulates the increase pressure controls ions liver the to to the blood different release uptake increase of the glucose; oxygen; supply it of tissues pancreas and the for thyroxine metabolic releases calcium prepare stimulates the which concentrations of eye. taut on too and which gland increases ● are and lenses. is is the rays lens treat drainage parathyroid it ● that body organs ● the draining development ● lens. so receptors. waves brain eyeball replacement die testes; an light caused kidney; and to glands pituitary the ● pupil the distance. getting by that children not retina by entering as need is of runs problem people Some also fluids ● of lenses. form Glaucoma The a condition lens. to the light and far pulling problem made Cataracts the by The which which lens light the a converging focus all at adapted The is easy focusing caused Astigmatism difficult ● is pressure is long specially ● cornea retina. near enough. corrected ● the responds sight convex the dilate eye the object muscle, the lens Long is the ligaments When reduces ● on in to stimulation defects up. suspensory The contract formed Accommodation the Eye sufficient image focusing ● iris give pass inverted control to contains the islets regulate the concentration release testosterone development which and also of releases the development secrete of progesterone Langerhans; that secondary oestrogen of is release in sperm the insulin blood production characteristics stimulates secondary which these glucose stimulates sexual that of the the sexual production characteristics; hormone that maintains pregnancy. 241 835292 CSEC HSB Unit B Topic 6.indd 241 08/01/2015 16:12 Practice Coordination Questions 9 Practice Which its target A person stands stimulus. relay In on which neurons a pin and order become do receives t he a painful motor, sensor y Motor neurone Ò sensor y B Motor neurone Ò relay neurone neurone C Sensor y neurone Ò motor D Sensor y neurone Ò relay Which not is is a B It C The fast has a feature response been of to modified neurone central It Ò neurone Ò relay neurone sensor y neurone neurone Òrelay Ò motor and one does a a Which are in A Motor B Sensor y C Motor D Sensor y Target glands hear t organ pituitar y C liver pancreas D pancreas liver gland kidney Which reflex of t he following results from increased secretion neurone adrenaline? A Increased supply B Increased blood of glucose C Decreased hear t D Decreased breat hing in t he blood. action? supply to t he small intestine. past rate. experience. always passes t hrough rate. t he system. involve t he production stimulus. by pat hway ner vous not of neurone any dorsal neurones B t hinking. 1 3 insulin B Section D of adrenal of It production active? A A of A and 10 2 site organs? A Site 1 t he control Questions of Section shows and roots of t he spinal The diagram shows a side view of t he human brain. ner ves? only. A 4 A bright Which neurones neurons and neurons light is t he is only. relay and shone response neurones. motor neurones. suddenly of t he into eye Iris to a human t his eye. stimulus? Pupil B C A Circular B Radial C Circular muscles muscles relax Dilates contract Constricts a muscles contract Name state D Radial muscles relax Changes by Which str ucture in t he one eye controls t he amount of t he aqueous ciliar y cornea D iris Explain t he Which of light t he in following t he human prevents t he internal iii) reflection how t he eye? from A, B and C and [6] of t he pupil are controlled change to B conjunctiva C cornea D sclera tissue A choroid B cornea C retina D sclerotic Where coordinated t he diameter when a brightly lit area someone into a dark [5] Explain in t he eye has light-sensitive cells? a are small C kidneys D pancreas t he b can Outline be t he of of treated. of t he t he two differ pupil ways are in from [2] shor t-sightedness and are two diseases of t hese two diseases and explain t he eye. how [5] impor tance coordination term [5] cataract causes t he of State actions actions. cause and t he by diameter voluntar y t he Glaucoma meant actions. corrected. is Explain hormones B in how t hey liver Changes Describe it is [2] involuntar y c A what reflex which choroid Which is involuntar y 2 8 diameter pupil cranial 7 labelled humour ii) A brain each. muscles C of of light place. 6 t he reflexes. walks B of enters? of A in cranial i) t hat par ts function Dilates b 5 t he Constricts of body. adrenaline in t he [5] destroyed? intestine 242 835292 CSEC HSB Unit B Topic 6.indd 242 08/01/2015 16:12 Unit B Reproduction B.7 B.7.1 The reproductive systems Learning By Types of the end reproduction is t he formation of offspring from t he of male and female gametes. It results in be individuals t hat have mixture of Asexual reproduction distinguish genetic information from t he two organism form a new is grows the and individual. formation then it Asexual of breaks between asexual of the information parent. These is identical offspring into two, reproduction genetically to from or one par t results in of parent. it breaks individuals describe the organisms, plants, it is the rare The in B.7 .1.2 process which known reproduce ver y Figure are including in as off, ● reproductive system describe female the whose that ● describe this way, ver tebrate shows two disorders in systems. Many and although animals. some bacteria of dividing by means dividing into male system various identical clones. bacteria male The the individuals sexual reproduction reproductive genetic you parents. ● to topic to: a and parent this able joining ● (fusion) of reproduction should Sexual outcomes binar y in ssion, two. reproductive system Once a boy reaches puber ty, he star ts p to produce sperm from his testes. Figure B.7.1.1 A medical technician p The puts a sample of cervical cells in Figure two str ucture of t he male is shown functions Figure of t he B.7 .1.3 in Figure B.7 .1.3. str uctures are Front genetically Bacteria divide identical cells. to form This is reproductive preservative system B.7.1.2 a The labelled described has proved women’s on number below. fluid. successful health of Cervical by cases in screening form of a clone asexual reproduction to give protecting reducing of a cervical of cells (×4000) the cancer view Side view ureter bladder vas deferens (sperm seminal vesicle prostate duct) gland urethra penis scrotum epididymis foreskin testes anus p Figure from B.7.1.3 the front The and male the reproductive side. Both system views show and parts associated of the structures urinary as viewed system 243 835292 CSEC HSB Unit B Topic 7.indd 243 08/01/2015 16:14 The reproductive Reproduction systems Vas Key deferens The terms vas deferens intercourse. is the Muscles in sperm the duct wall of that the carries tube sperm contract to by the urethra peristalsis during to move sperm. Sugar that added ! the Sexual reproduction Seminal organisms fusion of are male produced and by female vesicle The the is seminal added to vesicle provide is another the organ sperm with that adds secretions to energy. gametes Prostate (sex sperm. New gland This organ produces secretions, such as proteins and salts, are cells). to Asexual reproduction organism grows give rise to The that separate from tube urine. passing During in some way. There is of from the ureter intercourse a through sphincter the penis muscle at carries the top semen, of the as well urethra to stop any urine leaving the bladder. no Penis fusion semen. the contracts parent make new as individuals to The Urethra to sperm When stimulated the penis lls with force out the blood and becomes erect. Muscles in gametes. the Scrotum penis The testes slightly sperm Epididymis The are lower The cannot foreskin The testes hormone female Once a in her Front is Figure is a in reaches shown in B.7.1.4 long the is the by scrotum than at core 37 coiled testes are skin having the and B.6.4 she system. The Figure just body below the abdominal temperature. This is cavity at essential a as °C. tube and in are view covers their that See for which carried the end foreskin produce B.7.2 the the up sperm the vas are stored deferens after during role for of of sperm details the the penis. Some men are removed. of testes and secrete the process as the endocrine of male sperm organs. system star ts to release str ucture B.7.1.4. descr ibed that had organs puber ty, are the long reproductive reproductive system on girl survive testosterone. production The inside semen. intercourse. circumcised T estes held produced sexual to temperature epididymis being Foreskin contract The of t he functions ova (eggs) female of t he from t he ovar ies reproductive str uctures labelled below. Side view oviduct funnel of oviduct ureter ovary bladder uterus cervix pelvic girdle vagina urethra clitoris anus vulva p Figure B.7.1.4 part the urinary Topic 7.indd of The female reproductive system as viewed from the front and side. The side view also shows system 244 835292 CSEC HSB Unit B 244 08/01/2015 16:14 Reproduction The Oviducts The oviducts lines Ovaries these also contract ow created by The ovaries are female sex details of The Cervix The It cervix is clitoris sexual Various the in fallopian that eggs also order organs womb, the blood vagina The cilia to that of tubes. from the helps. reach The ciliated ovary Sperm an produce oestrogen production or is intercourse Clitoris peristalsis the as moves to have to epithelium uterus. swim that They against the egg. eggs and also and progesterone. and B.6.4 eggs the for the secrete See B.7.2 ovary’s the for role as an is a pear-shaped organ in which a foetus develops pregnancy. allows The known tubes systems gland. menstruation. Vagina also hormones uterus, during by the endocrine Uterus are narrow reproductive It the of muscle from allows elastic female it can the at the the sperm during end lining muscular stretches intercourse disorders of cells also an and is ring and to tube become of the near to the out vagina. during intercourse. the penis. baby When aroused reproductive to pass accommodates allow sexually uterus uterus after that to the the enter birth equivalent of of to the be penis stimulated and during born. during stiffens. systems Cancer Cancer is produces t he a uncontrolled lump or growt h division known of as cells. a This tumour. abnormal If a cell tumour is division detected early Key terms ! it can If a be removed by radiot herapy, chemot herapy or by surger y. Cancer tumour par ts to of is t he grow not detected tumour invasively. break It is early off, ver y t hen metastasis migrate serious if to ot her t his can occur. par ts happens of as t he it This is body can be t he cells have migrated. This emphasises t he and hard impor tance disease caused by the that is division of cells for uncontrolled star t to by mitosis. The nd cells where Any when form a tumour that may early invade other tissues in the body. detection. Follicle Why uncontrolled explain. Cancer involved are in genes types of growt h one t hat genes growt h If eit her, in t he bot h, to preventing Cancers detect in Ovarian tumours ovar y, potential centre of t he have cancer t he can egg is and involved cell cell proved diseases. The t he as same t hese are are type division 1 and difcult factors in anot her. involved. which type 2 t hat The are forms A structure inside the development of that ovary the for egg the cell. There two produces which to a produces division. are t hese Early star t cells of ten such attributed had t hem. of always mitosis genes for ms many has faulty, a diseases detection tumour and and will genetic diagnosis for m. tests is Some are impor t ant in from in t he epit helial early cells from follicles or until ovar y t he surface connective of tissue t he from t he ovar y. symptoms, of ten t hese is not are slows it tumours women cancer The by form cancer s. Ovarian Ovarian – are t hat to stimulates which of disease growt h body faulty occurs cancer which inhibitor or one of control inher it available not form promoter a people is division to as not detected pain ot her in t he causes. menopause. It t he abdomen, is more has bloating common in greatly and enlarged. back females pain, over are 50 who p Figure B.7.1.5 training on Nurses cervical receiving cancer 245 835292 CSEC HSB Unit B Topic 7.indd 245 08/01/2015 16:14 The reproductive Reproduction systems Cervical cancer Cer vical cancer is a Cer vical cancer is caused is a sexually cer vical available transmitted. smear to test provide Breast hand to X-ray) in t he at B.7.1.6 screen for Mammography is used have a early Since The for can are be any on 2008, cer vical by a t he womb. (HPV) giving vaccine which females has been cancer. of to t hose 50 and time. to t hose who of There t he are some positive actress be for t heir one of t he restricted to women; It (see risk. a one tests had a are of t he t hese so be two cancer risk genes t hat of be genes women have t heir af ter taken risk of testing breast t he can faulty Some lowering noted at This treatment, reconstr uction cancer. by (or women breast of mastectomy also breasts B.7 .1.6). of ten way for of removed t he radiograph is histor y is bot h a Figure This breast should men checking breast of or Jolie genes. A genetic breasts Angelina taken at have cases one by addition, breast radiot herapy. for have can In considered Removal by detected lumps. mammogram tested decision Uterine cancer Uterine (womb) can menopause. in t he grow causes in few vaginal cancer disease it is much rarer. seen T esticular examination by cancer is This a uter us t he is more lining uterine symptoms, common par ticularly called muscle t he older women, some as uterine sufferers par ticularly condition endometrium. known alt hough, in dangerous t he tumours Uterine experience af ter tumour Occasionally, sarcoma. can as cancer abnormal bleeding. Cancer B.7.1.7 of to grows Figure test). entrance cancer t he p t he papillomavir us detected against breasts t here responsible alt hough breast if later who not cer vix, human be smear followed a positive Figure t he age are is can families. t hat cancer. p in feel possibly t he t he t he protection offered t heir done It (Pap called of ten over of by cancer Tumours is cancer in males a doctor. Prostate cancer self- The enlarged frequent test tumour urination. known suggested as a t hat in t his Males prostate prostate case wit h specic cancer can t hese is block t he uret hra symptoms antigen (PSA) caused a by should test. It causing slow, t herefore has been but have a recently vir us. 246 835292 CSEC HSB Unit B Topic 7.indd 246 08/01/2015 16:14 Reproduction Egg and sperm production Questions 1 Make a table to compare the features of of the reproductive sexual and asexual reproduction. 2 List the 3 State 4 List 5 State 6 Distinguish the the the function parts the of male of the function three of female of between three the the parts system. you reproductive of the parts functions of have named. system. you the have sperm named. duct, the epididymis and urethra. 7 Explain 8 List why three may 9 parts the parts vagina of the and cervix female contain muscles. reproductive system where cancers occur. Explain B.7.2 the advantages Egg and of early sperm detection of cancers. production Learning By Production of the end t he body t here are stem cells t hat continue divide to Examples to of ● produce a constant supply of cells to replace dead cells. be t he describe Malpighian layer in t he skin (see Figure B.5.5.1 on page 194) and in bone marrow t hat produce red and white blood same stem cells number divide and by a of chromosomes type process known as are mitosis in t he in two produced. identical, might The lead cells mitosis. This except to t hat This means in t he t hat rare all t he cells occasions in when t he a body which t he daughter exact cells receive ● and about are mutation t hat t he grow is a and divide different half t he t his to type number type reason one become gametes nuclear division of divide by meiosis, in which t he t he parent cell. not of chromosomes of There of division in Unit C, so all you need to know for does same t he diploid halved of in number, meiosis not occurring double wit h each number number adult t he is testis line t he is from is to ensure generation generation, stays constant t he of par t supply of a In daughter of to t hat t he number generation. as you can see in constant at species is humans cells. This haploid t he t his not confuse is mitosis easy to and misspell completely contradict them the of Instead, Figure It of your answers. Mitosis it the division of cells in growth, B.7 .2.1. and replacement; in animals, 46. number is tip 46. number, In of chromosomes meiosis which is t his half in eggs just and for making sex cells: sperm. t he number t he is is diploid number. sperm formed outer of cells. called Production The features sperm. here the nucleus the is meiosis The the and Exam ✔ repair humans of daughter is In structure t hat meaning t he the cancer. chromosomes remains the genetically occurs, and is of sperm compare meiosis. more structure testis t hat Do cells the and describe eggs are you cells. egg These topic to: t he ● cells this able t hese ovary are of gametes should Throughout outcomes from of many t hese cells coiled tubules t hat seminiferous where develop into t hey tubules. divide by Stem mitosis cells to give a sperm. 247 835292 CSEC HSB Unit B Topic 7.indd 247 08/01/2015 16:14 Egg and sperm Reproduction production These cells inside of divide by meiosis and as t he daughter cells move towards t he first 46 46 generation into t he seen in of t he t he tubules mature t he t hey sperm diagram – mature, change you can see t heir role is in to t heir Figure appearance B.7 .2.2. nourish and Nurse protect and cells t he develop can also be development sperm. gametes nurse cell mature second 92 sperm 92 generation gametes third 184 generation dividing p Figure B.7.2.1 If human giving were produced by cells gametes mitosis the number rise to capillary sperm one of chromosomes double three be with each generations 184 in our cells generation. the tubule would number After p would Figure testis B.7.2.2 showing Section how through sperm are part of a produced mammalian inside tubules chromosomes Figure B.7 .2.3 tubule. shows p You t he Figure shows can cell part a photograph t he tails divisions B.7.2.3 through see of involved Photomicrograph of seminiferous of a mature in in a a t hrough in producing showing tubule section sperm t he a seminiferous centre. Figure B.7 .2.4 sperm. section mammalian testis 3 In general, it is said t hat men may release between 2 and 5 cm of from 20 semen 3 each to time 300 t hey million ejaculate, sperm and t hat each cm may contain million cells. That means a fertile man may release between 40 million and 1800 million sperm cells in total, though the majority produce between 40 and 60 million 3 sperm cells per cm , giving an average total of 80 to 300 million sperm per ejaculation. 248 835292 CSEC HSB Unit B Topic 7.indd 248 08/01/2015 16:15 Reproduction Egg stems and sperm production in testis Key terms ! Mitosis two parent tissues. B.7.2.4 The It is a an solve good with this family. all answer. girl t he is the born or so, but Y ou – to t he you will with will he your of 1500 his have to sperm cells develop from in the A sex cell A form – sperm egg. that is involved egg production. a stem cell is half of in The in that nuclear sperm the in division and number four the of daughter parent cell. in you sperm a to make else some or the in have a How many made assumptions. group, length producing with second. sperm lifetime? decide started answer of Mr sperm and or when how you It at Average and show even is therefore home Man’s he nished. arrive at an others. eggs a full complement develop age in someone have when until t he produce assumptions wit h development’ From as in 1 produce this Compare potential eggs. do life Production A men man problem to reproductive Record skills that average idea the occur same as sperm? estimated does T o many that the cells tubule Maths How changes and sperm cells seminiferous cells number cell. chromosomes a in and Meiosis Figure is of into or p The daughter Gamete mature involved chromosomes the divide nuclear replacement of is of growth, of develop form that repair cells A division a of into tiny eggs. number puber ty development of an of egg eggs of cells They in her go into a t hem star t to should stops be when taking contraceptive Figure B.7 .2.5 shows diagrammatically how Figure B.7 .2.6 shows a section ovaries form of develop released women t hat have ‘arrested into ever y are mature four weeks pregnant or are pills. photograph of a an egg is produced t hrough a in an ovar y. mammalian ovar y. 249 835292 CSEC HSB Unit B Topic 7.indd 249 08/01/2015 16:15 Egg and sperm Reproduction production ● Key ● Ovulation the 1 to 4 take approximately 14 days. Stages 5 to 7 take approximately 14 days. terms ! from Stages The release of an Ovulation egg is t he release of t he egg into t he oviduct (Fallopian tube). ovary. 5 The is 4 Ovulation: the follicle egg caught releasing the egg 3 The up follicle with waving by follicle motion of the leading oviduct to the and egg by becomes cells. mitosis The fills to surrounded follicle increase cells The follicle form cells secrete their cells the which left corpus secretes behind luteum in the (yellow progesterone. by divide number. 7 These this fluid. body) The enters uterus. ovary follicle cells the oviduct. 6 2 of into tube the a breaks funnel open surrounded by The corpus luteum disintegrates if oestrogen. the egg has implanted 1 An the immature influence egg of begins FSH from to grow the not into been the fertilised and uterus. under pituitary gland. p Figure have is not The Eggs and which a cells full that 30 of enzymes small differ B.7 .4.2). about is of eggs clockwise to in the help ovary you see of a the mammal. stages in The various sequence. In stages real life this case sperm and is egg make has the Production arranged differences B.7 .2.8 the B.7.2.5 been between greatly The times energy and packet cell of surround egg in stores is the the membranes egg that (see and and shape sperm from approximately than in enzymes the size cell wider eggs head form af ter digest Figures of of fat, a one 0.1 mm sperm. and also fer tilisation. a pathway B.7 .2.5 and cell another in Figures diameter, The cytoplasm stored The (see tip through of proteins of the the to sperm follicle B.7 .2.9). divides by meiosis p Figure B.7.2.6 Photomicrograph egg of an ovary showing one p follicle surrounded by some Figure filled Notice cavity in the the egg lager and B.7.2.7 The development of an immature egg follicles. cell maturing the from a diploid cell. Compare what fluid happens here sperm Figure with the development of follicle in B.7.2.4 250 835292 CSEC HSB Unit B Topic 7.indd 250 08/01/2015 16:15 Reproduction Egg and sperm production electron micrograph Egg cell jelly-like surface coating membrane of one egg of 23 chromosomes nucleus jelly-like coating of one of egg 23 cytoplasm chromosomes follicle cell middle nucleus piece p large numbers Figure of mitochondria B.7.2.9 An of human sperm x 500 to head supply energy tail Sperm p Figure much B.7.2.8 larger Human than a egg and sperm. These drawings are not to scale; an egg is sperm Written activity ✔ Comparing sperm and Exam eggs Egg Use all the features of information you sperm those with have of read eggs. so far Set to out make your a table table like comparing the this. or used Feature Sperm Egg chromosomes 23 23 (haploid) can include produced. you A can add woman low to Do to your whose allow structural some her eggs her Ovulation happens enters t he level to to roughly of t he oviducts. of t he cilia, events a woman’s menstr ual of in differences sources in to be t he normal Here, body it is regular t he stimulating can halfway whose contractions in t he the other follicle develop one called of mature action peristaltic of eggs using word sorts of structures speaking the egg is different in biology. human is the best term to use, but (haploid) everyone talks everyone will size see and what the you about know write eggs what and you mean it. numbers other features table. own stimulates features, research The all (ovum) when Y ou mean reproductive ovum of ovum? to Strictly Number tip FSH moved t he t he star t a a fer tility woman’s slowly beating in as (FSH) is too dr ug. This way. between muscles from given hormone towards carries t he oviduct. of one periods. egg The period t he t he egg uter us along, regular to The by and by pattern next is cycle. 251 835292 CSEC HSB Unit B Topic 7.indd 251 08/01/2015 16:15 The menstrual Reproduction cycle Questions 1 Outline 2 Use 3 4 Learning By the end outcomes be of this able topic describe differs How many each egg Compare explain B.7.2.4 from is which and the corpora that in B.7.2.5 to lutea are produced describe development of (singular: how in the the testes. development of sperm. corpus luteum) are produced for released? seminiferous The sperm tubules menstrual with follicles. cycle you menstrual cycle to: menstrual cycle is a series of changes t hat takes place in t he body of ovulation a ● Figures B.7.3 The ● process eggs The should the the roles woman in the prepare for t he possibility of pregnancy. The cycle itself lasts of about hormones to a mont h (typically between 25 and 32 days). menstrual cycle. M e n 1 s t r terms ! 26 3 Days If Menstrual cycle A series no 26 changes that occur in to 28 fertilisation, 4 25 corpus of u Key 2 luteum the stops secreting 5 24 reproductive to prepare system for of the female progesterone Days Lining pregnancy. Release of an the ovary into an of to 7 breaks uterus down egg Days from 1 6 23 Ovulation a t i 28 27 oviduct; Corpus 18 to luteum 25 secretes 22 it occurs half way through 7 the progesterone to Menstrual menstrual maintain cycle. the lining of Days 21 the grows 20 19 Egg the 18 is 12 to to released ovary (about at day an ready to 9 embryo 10 from 11 14) 12 F of be 13 15 outline 11 uterus ovulation 16 An the 17 17 B.7.3.1 of receive Days Figure to 8 Lining p 8 cycle uterus the er til e 14 p e rio changes that d occur during the menstrual cycle The events of the menstrual cycle are summarised in Figure B.7 .3.1. Figure B.7 .3.2. shows the changes throughout the cycle in the ovary, including the development and release of the egg, concentrations of two hormones from the pituitary gland (follicle stimulating hormone (FSH) and luteinising hormone (LH)), concentrations of two hormones from the ovary (oestrogen and progesterone) and the lining of the uterus, which is known as the endometrium 252 835292 CSEC HSB Unit B Topic 7.indd 252 08/01/2015 16:15 Reproduction The cycle secreted is by The coordinated t he by pituitar y hormones. gland. This At t he star t stimulates of t he changes cycle in FSH t he While to t he t he ovar y hormone, uter us more in release is of is to preparation A surge egg. producing oestrogen, FSH. an in for LH an t he egg FSH in t he embr yo. and t he follicle, repair and Oestrogen causes it releases growt h also ovulation of stops to t he as release t he cor pus hormone, for it of egg, luteum LH nourish It does t he stimulates (yellow progesterone. pregnancy. will t he The t his body), effect by t he to of remains remain of lining release of and of stimulating t he wall is of to pituitar y an gland egg in stimulates a follicle. their of oestrogen stimulation the known by by the the ovaries hormone pituitar y is FSH due from gland. anot her prepare t he the produce any Production follicle, secrete progesterone by to t he occur. t he ovar y anot her t he to Af ter secreted the stimulate cycle ovar y FSH leading menstrual uter us t he to body grow so embr yo. The secretion of oestrogen production LH inhibits of the fur ther FSH. released; yellow body forms ovary Oestrogen stimulates of repair uterine and growth lining. relative concentration luteinising in the blood hormone (LH) Ovulation of FSH hormones follicle from itself and a hormone the pituitary hormone gland is triggered sudden by surge a in small surge in luteinising stimulating (LH), also produced by the the rise (FSH) pituitar y relative gland. progesterone concentration in the blood This of surge in LH oestrogen hormones is triggered some 10 days by or so in after from menstruation. the ovary Lining shed Oestrogen (menstruation) by ovary; uterus Progesterone released lining starts of to released yellow body; lining uterus continues Lining by down of to pregnancy thicken does thicken lining breaks if not After occur ovulation LH causes the remains of the of follicle uterus which to develop continues which into to stimulates days 7 days 14 days 21 days 28 corpus produce the uterine 0 the luteum progesterone, maintenance of the lining. days time/days If p Figure B.7.3.2 The menstrual cycle: changes in the ovary, the concentrations of there the four If a hormones woman control becomes progesterone, fer tilised that and t hus t he the menstrual pregnant, preventing embr yo does her cycle cor pus and the luteum t he release of not implant changes goes anot her into t he in on egg. uterus and t he of egg t he progesterone is secreted from t he ovar y, t he lining of less and FSH is secreted again from t he luteum implantation degenerates progesterone is is released. not t he uter us decrease breaks in causes the progesterone the shed down successful uter us, This less no corpus secreting If lining the is the - uterus lining concentration to be menstruation. pituitar y. This seems complicated, but remember that the pituitary gland is coordinating the ovary and the uterus, so that their activities are synchronised together. It is important that the uterus is ready to receive the embryo just after it has been p Figure the B.7.3.3 menstrual Hormonal control of cycle released at ovulation. The ow char ts hormones in Figures interact in t he B.7 .3.3 control and of Figures t he B.7 .3.4 menstr ual illustrate how t he four cycle. 253 835292 CSEC HSB Unit B Topic 7.indd 253 08/01/2015 16:15 The menstrual Reproduction cycle Start of Stops cycle pituitary making FSH FSH made Oestrogen by made Ovum ovary inside If no by develops pituitary follicle pregnancy, progesterone production stops menstruation If and occurs pregnant, Progesterone LH Ovulation progesterone made and by made by oestrogen corpus continue produced p Figure B.7.3.4 Hormonal Maths This are bor n number T able T able with a in very the the of the menstrual cycle 2 large increases shows eggs control skills never B.7.3.1 potential q pituitary to be Girls luteum number during results ovaries of a during of their potential lifetime. study the into the in fact, their it changes reproductive life of ovaries. decreases. in numbers human of females. B.7.3.1 Age/years Mean number of potential birth 1 Draw 2 Calculate 3 eggs In a line birth and Use your potential 712 000 7 468 635 14 402 067 21 175 700 28 166 231 35 89 145 42 39 874 49 9 956 56 3 450 graph the the to show decrease in the the age of 56. answer to question eggs over the same figures mean 2 to in T able number calculate time eggs per female B.7.3.1. of the potential eggs percentage between decrease in period. Questions 1 State b 2 4 role oestrogen, What and 3 one is in the of c each FSH, role of of d the the LH, e following hormones: a progesterone, testosterone. pituitary gland in sexual reproduction in males females? What happens when the What happens when the lining lining to of to of the the the the concentration uterus gets of thicker concentrations uterus oestrogen breaks of during and the oestrogen down during progesterone menstrual and the cycle? progesterone menstrual cycle? 254 835292 CSEC HSB Unit B Topic 7.indd 254 08/01/2015 16:15 Reproduction B.7.4 Fertilisation Fertilisation and implantation Learning By the end and implantation outcomes of this topic you Fertilisation should Fertilisation is t he fusion of a haploid sperm wit h a haploid egg to diploid zygote. Fer tilisation occurs when one sperm gets t hrough membrane of t he egg (see Figure B.7 .4.2). When t his explain happens, t he produce a number. of t he fer tilised The days each days when egg fer tilised mont h fer tilisation determination Sex determined appearance in t he by and t hat cell when Sex is sperm a is two t he has is 46 called newly of t he chromosomes chromosomes a zygote. released possible microscope 23 (see egg is Figure in Figure C.1.7 1 t he egg all, t he usual are an only two oviduct. known on sperm arrive combine describe in t hree These are t he at as page begin X and Y af ter t heir 280). to egg Figure B.7.4.3 Fertilisation: a sperm 46 2 in fertilisation. diploid or reaches diploid vitro to p 46 implantation. B.7 .4.1). chromosomes, (see in There of fertilisation describe 23 ● chromosomes to: t he ● outer able form ● a be cell diploid ovary in cell sperm enter try an egg to egg testis Key terms ! Fertilisation and The fusion of an egg sperm. Implantation The embedding of 23 the embryo in the lining of the uterus. 23 haploid fertilisation 3 haploid one sperm succeeds. sperm Its nucleus enters the egg cytoplasm and the 46 of moves egg’s the egg towards nucleus diploid zygote p Figure B.7.4.1 chromosomes The is diploid restored number at of p fertilisation Figure an B.7.4.2 Sperm fertilising egg Implantation Implantation is t he process by which an embr yo becomes embedded in p t he lining of t he uter us. Figure B.7.4.4 fertilised nucleus During t he six days or so af ter fer tilisation, t he zygote moves slowly oviduct, dividing rst into two cells (Figure B.7 .4.5), t hen into four the egg t hen lining of into t he a ball uter us, of a cells. Once process it called reaches t he uter us implantation u Figure after (see it B.7.4.5 About fertilisation, mitosis for genetically settles Figure the the first sperm can see of a the and the nucleus the first nuclear about to start of a individual new (x 300) t he B.7 .4.6). twenty-four embryo time identical into the photograph you cells division and from this egg down of t he In human to cells hours divides produce by two (x300) 255 835292 CSEC HSB Unit B Topic 7.indd 255 08/01/2015 16:15 Fertilisation and Reproduction implantation four cell stage ball of cells inner the two cell of stage embryo occurs By ball sperm said of implants 5 now unsuccessful fertilised lining uterus to 6 there cells to are is start in days the uterus after lining approximately known once this fertilisation. as an 100 embryo. implantation cells and the Pregnancy is occurs egg (zygote) oviduct p Figure B.7.4.6 Case In In vitro outside a woman’s help be healt hy her uter us, egg to a follow ● The she woman will t hey ● ● is would implantation IVF. given at t he and test tube). The fer tilised eggs 37°C staff t he stored If procedure t he babies are a semen of ten in are to t his a fer tility is is many by This why could are t he a sperm late couple and has happen unable couple a t he normally t hey case in reasons eggs t hat t he fer tilised developed conceive. so be are are increase around anaest hetic to a if carr y might t he decide t he half just number of a eggs a dozen few hours eggs are before ovulated. of mixed semen lef t to develop to t hree choose one t hat or t hey nitrogen successful, by toget her two hope liquid to Usually under sample for is dr ug ovulation. woman eggs in egg was follows. The medical unable of an produces damaged, cycle produces uter us There woman be normally at when If man The and technique uter us. The t he ● as from incubator ● t he produce removed ● is a may treatment procedure if become into occurs The couples. e.g. she have fer tilised (IVF) body. infer tile infer tile, oviducts The fertilisation fertilisation fertilisation to might between study v itro 1970s Events masturbation. in into small young Petri dish embr yos in (not a an days. more of t he implant. as a ‘frozen nine embr yos Any spare to transfer embr yos to are embr yos’. mont hs later one or more healt hy born. If a couple is unable to have children because of problems with the man’s sperm, the woman may benet from articial insemination. Sperm from a donor male are collected and then inserted into her uter us at ovulation. p Figure B.7.4.7 A technician at An alternative treatment is to take a nucleus from a sperm cell and insert an IVF sperm clinic injects an egg with a it into an egg as you can see happening in Figure B.7 .4.7 . nucleus 256 835292 CSEC HSB Unit B Topic 7.indd 256 08/01/2015 16:15 Reproduction Pregnancy Some couples t here is a risk muscular be t hen gene t he few and or a to to cells t he are use child to conceive t heirs an egg has out to is what is a child inheriting carried This can IVF of Af ter test not. embr yo returned a any dystrophy. removed faulty decide of divided see if genetic a few t hat happening be inser ted into embr yo. Human embr yos t he because a in Figure uter us. can times embr yo The t hey disease, one has cell develop cell If it role of the placenta as can t he hasn’t, cannot normally the know such inherited 7 .4.8. and be even if removed. Questions 1 Describe how IVF is carried p out. Figure an 2 Explain why fer tility dr ugs are used in IVF. B.7.4.8 embryo that it has condition 3 Suggest likely reasons for a couple seeking to have Explain disease t he in advantage t he of IVF for a couple who cell not that is inherited runs in removed by IVF a to from check genetic the family of one IVF. of 4 A produced have an the parents inherited family. Questions 1 What are 2 Explain 3 Why 4 Describe what happens at fertilisation. 5 Describe what happens to a is gametes? how the the male female gamete gamete reaches much the larger zygote female than during the the gamete. male few gamete? days after fertilisation. 8 List, in the passes, 9 Name correct from the order, where nuclear it is the structures produced division that to gives through where it rise the to which meets ball a the of sperm cell egg. cells after fertilisation. B.7.5 Once ball Pregnancy implantation of cells During has implanted pregnancy, the happened in t he and t he t he lining embr yo of role of woman her greatly is the said uter us increases is to placenta be called in size pregnant. an and Learning The By embr yo. main stages pregnancy in are t he development summarised as into a baby ready to be be of this able born at t he describe the end ● of end topic you to: complexity. ● The the should outcomes follows. the development of embryo describe the role of the placenta ● One month af ter fer tilisation (see Figure B.7 .5.1 and B.7 .5.3) a human ● embr yo yet ● is are ● have Two It arms months now a bit or a and months developing like legs, af ter called formed Three are looks a sh but it embr yo is clear fer tilisation foetus. t he It hear t af ter is is t he about (see tadpole. where t hese embr yo 45 mm The will looks in embr yo does explain the mother and needs of the not foetus. develop. much lengt h. more Most of human. t he organs beating. fer tilisation rapidly or t he Figure ner ves B.7 .5.3). and The muscles foetus is of t he about foetus 90 mm in lengt h. 257 835292 CSEC HSB Unit B Topic 7.indd 257 08/01/2015 16:15 Pregnancy and the role of the Reproduction placenta ● ‘gills’: these develop gills of in a have much fish do no function the same before Five but way that the t he months foetus the next few carries and 180 mm in lengt h, nger prints hair. Its movements may have been felt by t he mot her for and t he last mont h. Seven The cord: oxygen months af ter fer tilisation development is almost complete. placenta As to soon removes waste products from cells t he of embr yo t he implants embr yo, into placenta. The shown Figure str ucture toget her t he of t he wit h lining cells of placenta a from t he few t he uter us, mot her, some mont hs into form of t he pregnancy is it arm bud: which from an of substances As will in B.7 .5.2. between There t he is a ver y mot her’s large blood surface and t he area for blood of t he t he exchange foetus. arm this develops as and t he t he embr yo develops it secretes a hormone called human chorionic grow into gonadotrophin(HCG). the lower the backbone part of leg a bud: leg from will Figure B.7.5.1 Embryo one This causes t he cor pus luteum to continue to secrete which progesterone. grow pregnancy p about ngernails, nutrients the embryo ‘tail’: only eyebrows, eye ● umbilical alt hough formed weeks mouth developing fer tilisation, perfectly disappearing body within af ter has month As and a result, t he t he lining production of of t he FSH by uter us t he wall is pituitar y maintained gland is during inhibited. after This ensures t hat ovulation does not occur during pregnancy. Af ter t hree fertilisation mont hs, cor pus 1 deoxygenated blood: eventually t he placenta luteum in t he takes ovar y over t he role of secreting the and mother’s receives mother’s heart food hepatic and lungs substances portal and t he returns 2 to progesterone degenerates. to be from oxygenated blood: from the mother; oxygenated also rich in sugars, and antibodies amino acids, vitamins 2 4 the vein 1 lining of uterus 4 blood blood. capillary network of but 3 vein in useful umbilical substances cord: such carries as oxygenated glucose and blood amino space This in uterus: comes very contains close to the the mother's foetus’ blood placenta does not actually mix with it and acids 5 umbilical cord: connecting the foetus to 6 from the special Foetal placenta type of to the haemoglobin haemoglobin is normal haemoglobin. diffuse from blood cells the of foetus. better As a mother's the Foetal called at red foetal picking result blood blood a the 5 3 placenta haemoglobin. up oxygen contains oxygen than molecules cells to the 6 red artery blood foetus in and foetus to umbilical waste the cord: products carries such deoxygenated as urea from the placenta foetus p Figure B.7.5.2 Structure of the placenta and the The umbilical blood come foetus are mot her Figure 28 at B.7.5.3 days left. A human development, Most of the formed and the already beating embryo with organ the after of ten belong might die t his t he of mot her in organisms in mot her t he to vir us if and foetus ot her. to blood is study on t he foetus mot her’s developing causes page baby. r ubella blood being actually impor tant blood mixed blood monoxide never is The different its carbon This different. case and t he t hat including each genetically about t he mot her to t he groups. wit h 261. kept are of t hat foetus When of Anot her apar t generally However, is mix, its t his any to vir uses, measles), as and can t he cross and well t hey mot her t he is case, of t he t he There is of blood t he more disease-causing pass from including as and blood t he mot her. t hat (German lead, t he advantage unable some alt hough because cer tain t he HIV and chemicals placenta. head systems embryonic t he close foetus t he p of ver y cord heart are is 258 835292 CSEC HSB Unit B Topic 7.indd 258 08/01/2015 16:15 Reproduction The The is surrounded secretes mechanical uid is the from developed uid amnion The the from have by amniotic damage, formed Cells the e.g. foetus’ the skin foetus the lungs. does not provide of are transparent This the blood has into out makes a the some mother for and of the connective foetus sudden it present to bot h provide pregnancy as a t he in also of t he morning 12 pressure oedema on her amnion and into the the similar when to placenta the movements uid and This organs taking drinks it. The foetus. soles over (but some t he of of not caused pregnancy. and t he ankles), is which and t he be a nausea is not (most womb, (due it is a t he of of a a day. It put toilet During a her pregnancy number healt h and of a tests t hat of t he be associated hyper tension. happens at an blood, signs antenatal of go out developing in What should carried concentrations wit h her woman will regularly during foetus. her These diabetes and to an A seven-week-old amniotic sac, to the placenta by the to the placenta at right attached umbilical cord The on to drive, skin across in disorder) may t he and make. antenatal pregnancy include its can due sexual baby in – pronounced liver t hat B.7.5.4 embryo limited sick. stretching more demands t he be women to loss to to Figure (feeling always t hroughout visits are on changes woman symptom additional demands hormonal backache itchiness can include friends Never t heless a frequent experienced, and it cause enlarged mental Nausea experience always, tiredness, from by family suppor t. and necessarily) pregnancy), itching feet, money not women but breasts, legs do emotional physical sickness’ mont hs can, where and par tner, Figure the her the plasma. p Here of foetus woman’s practical bladder (swollen and worries and during abdomen; palms early t he considerable may tender kg if ‘morning changes include around helps ver y These result hormonal t he makes mot her. especially to role any p pregnancy sick) the tissue against movements. composition breathing urinates nutrients layer protects mother foetus any uid and shed carries The the thin, when into needs a uid. ltered During t he and amnion foetus that Pregnancy to tests preeclampsia B.7.5.5 womb just A full-term before foetus in birth clinic. check on iron which is clinic? A woman can expect the following things to happen at her antenatal clinic. ● She will be asked about her medical record, general healt h and personal circumstances. ● Her of week t he as lactation blood Too high cope can fatal, she her cord, can in bot h t he to each put uter us, t he reser ves visit. on pregnancy. fat will extra is be pressure build condition expect her growing and t he a of on Af ter between This is may rst about due placenta, t hat t he to t hree 400 g t he up to 500 g increasing amniotic build mont hs in uid mass and anticipation of production). blood wit h for measured pressure a result This be result (milk Her to a foetus, umbilical ● will pregnancy, per of weight up of regularly indicate demands known mot her taken may made proteins as and foetus on and toxaemia if it to t hat it t he waste not t hat it mot her’s owing which is check to t he substances can be is not body too is high. failing pregnancy. in her dangerous, This blood. or even treated. 259 835292 CSEC HSB Unit B Topic 7.indd 259 08/01/2015 16:15 Pregnancy and the role of the Reproduction placenta ● An internal t hat she smear ● Blood is not may be tests will to p Figure B.7.5.6 showing a Ultrasound healthy foetus scan 22 An ● HIV pregnancy. can you How many Urine be also measles test tests check taken to in case check for see anaemia. t hat she tests t hat cer vix (a early needs see and t hr ush t he These she to vagina as stages has an of allow made cer vical see cer vical cancer. woman’s blood has to A haemoglobin t he emergency woman be condition). enough also t he will fungal and blood transfusion. antibodies to (r ubella). may will to her such be be carried taken to out. indicate t he diabetes see if t hat glucose can or proteins develop during are present. Glucose pregnancy. structures ● identify? taken noted, will of infections weeks may into be doctor German ● no developing group A examination has Ultrasound scans may be taken later in pregnancy. These allow the mother and the person operating the ultrasound scan to see the developing foetus (Figure B.7 .5.6). The foetus can be checked to see that its heart is beating normally and that there are no physical abnormalities, including Down’s syndrome. The sex of the baby can sometimes be identied, though some parents prefer to nd this out only at the birth itself. For more defects information (page Checking There are for two genetic main abnormalities The t he rst is uter us usually cells t hese Secondly, is taken two or This is in genetic t hese a age days to can social in t he to used weeks and the physical causes of bir t h foetus foetus t he t he and or to is sample into may be checked for inser ted t hrough t he of t he in culture genetic genetic (CVS), a presence cer tain grows t hree sample The of Amniotic for wall uid. uid to of This is contains four weeks, abnormalities. pregnancy. placenta amniotic pregnancy. grown sampling into t he needle a cer tain villus reveal a take being for harmed be to 16 weeks because being reasons, where 35 serious to chorionic 8-10 which where Af ter tested identical genetic of t he sample from from can genetic cells in t he be placenta tested wit hin abnormalities. t he embr yo, so is foetus. CVS, of a help t here is a small miscarriage t he foetus if risk (about resulting. it is found In to 0.5 to 2%) addition, be of neit her suffering from a abnormality. women by 14 amniocentesis foetus technique For be possible bot h t he see pregnancy. amnion foetus. about t hree t he about can genetically In in in amniocentesis, t he cells t his abnormalities ways early and done from on 266). or are two is a a This family disorder, more techniques signicant abnormality. because genetic women t he t here likely to might member such as give tend chance be is cystic bir t h to only t hat to because already brosis offered foetus t he sickle wit h to to may mot her known or children be t he be cell is pregnant be affected over t he affected anaemia. Down’s by a Older syndrome. 260 835292 CSEC HSB Unit B Topic 7.indd 260 08/01/2015 16:15 Reproduction Case Pregnancy and the role of the placenta study Rhesus d isease Rhesus Y mother Y negative placenta Y Y antibodies cells second Y blood Y Y Y blood Y foetus with Rhesus + Y Rhesus positive + red Y foetus with Y against positive Y first Y Rhesus positive Y blood Rh+ antigens a First b Between pregnancy p Figure c pregnancies B.7.5.7 antibodies A mother against foetal who red has pregnancy Rhesus blood Second cells if negative it has blood Rhesus will make positive blood As part of antenatal screening, women are offered blood tests to determine their blood group. You may remember from the case study about Declan (see page 129) that blood groups are A+, B-, AB+, etc. The blood test for pregnant women determines whether they are Rhesus positive or Rhesus negative. Some people have red blood cells with a marker on the surface that is known as D. People who have this marker have Rhesus positive blood, those who do not have Rhesus negative blood. This is determined by a gene in a similar way to the ABO blood group system. The Rhesus blood If wit h positive Rhesus foetal cross red t he blood t he as it into will happens t he and so of t he is red at because mot her’s The is develops blood if blood jaundice. disease t he her end The to does is cross a cases, destroy not t he harm red t he a child cells system body, placenta t he blood immune will t he positive. produce placenta by back into when is remain baby’s early red a born, in If t he blood t he she is occurs next exposed to antibodies disease t he baby circulation However, stillbir t h t he t he mot her’s Rhesus antibodies her invade cross affected. Rhesus body causing wit h and foetal has against cells. t he not foetus so ot her into is can during blood, antibodies some organisms blood cells time, cells In continuing red antibodies may born. its pregnancy risk blood pregnancy it red rst second immediately. destroy destroy impor tance negative produce antibodies a Rhesus This great foreign blood bir t h cells. she of Rhesus These Rh+ before blood, is has when pregnancy The who does leakage slowly, system antibodies. foetus This woman, placenta responds, making a group pregnancy. in in t he baby but is baby’s pregnancy, unborn dies it cells t he in foetus. t he womb anaemic and circulation for a few af ter mont hs. mot her. 261 835292 CSEC HSB Unit B Topic 7.indd 261 08/01/2015 16:15 Pregnancy and the role of the Reproduction placenta A Rhesus negative woman, pregnant for the rst time, will be offered injections of antibody against Rhesus positive blood cells (anti-D) during her pregnancy, so any foetal blood cells that cross the placenta are destroyed before her immune system realises they have arrived. She is not exposed to the baby’s red blood cells and her body does not make any antibodies. Rhesus Study ✔ tip anti-D You can nd antibodies odd out more Unit D.6. about work. It as seems a mother would antibodies against her but in that in remember the and foetus he will that come be disease injections half the from Rhesus produce own foetus, genes the father is now t he Doctors well as t he deliver y, will to t he specialises in previous af ter t he t he t he is caring likely for to If it a is prevented woman t hen pregnancy more If will foetus because anti-D. pregnancy deliver y. treatment give child in a called monitor baby disease, necessar y uncommon antibody antibodies Rhesus be of a be an unborn depend blood t hese how to a t han does do not usual, develop severe unit using developed injections closely baby transfusion admitted newborn on has it is. in severe in a It may cases. hospital Af ter t hat babies. positive. The inheritance of t he Rhesus blood groups is explained on page 289. Questions 1 A woman who is who Rhesus pregnancy, advice are so has Rhesus positive. medical t hey likely Explain how a child 3 Explain why a Rhesus red 4 blood Explain cells how developing of t he t he gives not have staff did not realise give wit h her blood did to 2 negative She her in Rhesus negative case bir t h blood t his she disease mot her a test was child her What pregnant anaemia makes a likely. becomes has to during and antibodies again? jaundice. against t he foetus. treatment for Rhesus disease prevents t he foetus disease. Questions 1 State the role 2 State three of the amniotic substances that fluid. will pass from mother to foetus across the placenta. 3 State four things that a woman can expect to happen at an antenatal clinic. 4 Describe 5 Explain how the placenta is 6 Explain why the umbilical vein 7 How 8 Explain 9 A of how does why on woman oxygen pregnant this a a move foetus woman her should is foetus? adapted from and its found take care for carries the Suggest be its are health the during pregnancy. functions. blood blood. into genetically anaemic. how her oxygenated mother’s mother to of What woman foetal blood? different. are will the the be likely treated effects for her anaemia. 262 835292 CSEC HSB Unit B Topic 7.indd 262 08/01/2015 16:15 Reproduction B.7.6 Birth Birth Learning By the end outcomes of this topic you Birth should By t he end of pregnancy t he baby normally lies in t he womb wit h its t he mot her’s vagina (Figure B.7 .6.1). This is considered t he to give bir t h position to enable as t he bones in t he baby ’s head are in t he to: describe the describe some birth process ideal ● position able head ● towards be possible birth correct defects it to squeeze t hrough t he bir t h canal. ● explain ● pubic bone (front of pelvic placenta: some multiple describe post births natal care. girdle) weighs Study ✔ 500 g Look at the tip drawing of the skull in vagina umbilical cord: 50 cm long 2 cm thick and Unit B.4.1. The of foetus have so a they during amnion: Figure B.7.6.1 Sometimes baby’s t he bottom is The t hat of to any First stage Labour t he of muscular t he ever y 20 as late During of head rst to of in other birth. is and labour a neck baby Toget her out are t he t he position of t he lying t hey are known womb across include mot her Later, caused t he as ‘breech’ instead t he of neck bir t h called begin is This cer vix to to an pass contractions become some released. can wall down at can labour, once her t he of be for where head. t he t he ‘Breech womb. divided reasons t he in This cer vix t hey into a which frequent labour These Eventually come and hormone stage bir t h is uter us. known dilates t he contractions. rst more of is rst At any t he gradually t hrough. of point This happen end t he vagina. secretion At coming t he comes by feels t he t he t hey gland. uid baby of t hrough pituitar y labour labour be t he t he when B.7 .6.2). as stage surround minutes. amniotic (Figure together each backbone contractions Contractions t he fused over skull are labour baby mot her’s the mot her. begins push the can near where stages. clear of first baby is events part The transverse’ number not slide of intact lower p can bones t hey are ver y amnion as t he of labour, will approximately oxytocin t he are breaking intense. from t he breaks of t he and waters and can even wider). The rst occur canal. (becomes has dilated typically enough wit hin 4–12 for stage t he hours of baby’s t he star ting. Delivery The second cer vix a into stage t he continuous along and of labour vagina. bir t h wit hin The canal. 10–60 begins as uter us, Strong minutes t he baby ’s cer vix and contractions t he baby’s head vagina is pushed toget her continue head to emerges out of now push from t he t he t he form baby bir t h 263 835292 CSEC HSB Unit B Topic 7.indd 263 08/01/2015 16:15 Reproduction Birth placenta fetus muscle of uterus contracts umbilical cord baby’s passes into p Figure canal. B.7.6.2 The midwife specialises Babies can canal. The few rest (a in t he umbilical and t he get of separate t he stage baby’s who quite of body specialises the cervix vagina labour follows in wit hin bir t hs) shor t of oxygen white babies air, of ten accompanied for t he red cord is of blood or individuals cells t hey look to by minutes, obstetrician in t hese (Figure two places clamps pass bluish cries, develop oxyhaemoglobin. clamped between may as of presence cord second the helped (a by doctor a who bir t hs). skin breat hs to of nurse sufciently due The head through is to soon t heir Once cut. out t hrough immediately t he prevent Mot her t he oxygenate bir t h. t he usual reddish baby is child A blood colour breat hing, subsequent and bir t h af ter t he bleeding are now two B.7 .6.4). Afterbirth Contractions and t he (Figure of t he placenta muscular and wall umbilical of cord t he are uter us soon continue pushed out af ter of deliver y, t he vagina B.7 .6.3). clip placenta (afterbirth) u Figure labour B.7.6.3 is when The the third stage afterbirth of emerges 264 835292 CSEC HSB Unit B Topic 7.indd 264 08/01/2015 16:15 Reproduction Birth Complications Various we t hings have Breech If t he baby’s t he might may If occur so bottom so end t hat of t he pregnancy bir t h is not quite as straightfor ward as far. or detected baby take be the birth position. turn can indicated at around longer used or a feet early so t han emerge enough, t hat it usual. Caesarean is rst a born This t he head could section baby midwife or is said rst, as endanger performed to be obstetrician to normal. t he in If baby, remove t he may not, so breech be able to labour forceps t he baby from t he baby out t he womb. Forceps Forceps delivery can t he uter us risk t hat be if used t he t he to turn mot her’s baby’s head t he baby around contractions may be are damaged or help rat her ease weak. during a There forceps is a of slight deliver y. p Alternatively, a suction device, a ventouse, may be used. This is Figure B.7.6.4 Mother with newborn attached baby to t he same baby’s time as Caesarean This is a a is is to t he t he doctor or midwife gently pulls t he baby at t he contracts. wall healt h labour when anaest hetic from t he procedure abdominal risky prolonged This and mot her section surgical mot her’s and head t he t he will abdominal and of are need which It can get stay in baby can mot her offered to t he uter us. t he baby caesareans and in be and tired, to t he is ‘born’ used baby. causing hospital when If mot her. t hrough t he its longer labour mot her hear t The rate mot her until a she cut is too has to is has in t he long had drop. given an recovered surger y. Induction Induction t he is amnion injection of an – ar ticial so t he baby may be bir t h is Birth defects process releasing hormone induced overdue by if t he oxytocin t he more t hat triggers amniotic healt h t han a to of week uid induce t he or labour, – or by (star t) mot her, or eit her giving t he by cutting t he mot her contractions. baby, is at risk or an A if t he two. Approximately 97% of all babies are born strong and healthy. Sometimes, though, this is not the case. Birth defects may have genetic or environmental causes or, in some cases, both Genetic causes There are are follows. as many of genetic Down’s syndrome This of a means its cells. roundish life t hat wit h it People face. expectancy. Down’s birth defects causes of bir t h defects. Some of t he more common is when the baby has an extra copy of chromosome 21. has 47 wit h They The chromosomes, Down’s generally older syndrome. a have couple, The instead syndrome have learning t he mot her’s more age is of t he usual 46, almond-shaped difculties likely more t hey and are to signicant a in each eyes and reduced have t han a child t he fat her’s. 265 835292 CSEC HSB Unit B Topic 7.indd 265 08/01/2015 16:15 Reproduction Birth Sickle at cell anaemia carr ying have a is oxygen. characteristic signicantly a disease Under in t he shape which a person’s microscope (see genetic t he blood person’s variation). Life is less red efcient blood cells expectancy is of ten reduced. Cystic brosis is a disease in which the person’s lungs produce a very sticky mucus (see table on genes). Life expectancy is signicantly reduced though medical advances have been made in recent years in the treatment of cystic brosis. Social The and environment exposure Figure palate birth B.7.6.5 – an A child with environmentally a cleft caused to of listed below. Spina bida in its t he t he is severity: a condition out of) some t he birth about to defects. cer tain environmentally in which par t ver tebral people defects bir t h exposure common independent effects lip child of af ter a wit h of spina bida possible caused t he column. Two metals bir t h spinal The are suc h cord as causes are aluminium. defects are protr udes condition paralysed; varies ot hers greatly lead lives. smoking bir t h a be and mot her born facial To herself a t hese successful same operation to child is needed higher much likely t he in child), rest sleep, and to effect baby more risk of be is B.7 .6.5. Figure t he on t he foetus. to have tract dying a from a signicantly a split in t he eit her parent cot baby less If a same signicantly infections during its deat h. pregnancy, Such is shows condition. likely during This B.7 .6.6 respirator y alcohol to Figure correct serious t he in (palate). syndrome. t he woman of seen has her baby may characteristic intelligent t han would case. extra limit woman will folic medication unborn a suffer bot h pregnant are to alcohol been t hat have a (supplements unnecessar y The and have be mout h mot her, too foetal ensure possible, as drinks features help can have can t he operation t he weight, to wit h ot her wise of successful reduced life palate roof especially If B.7.6.6 clef t t he smokes, early Figure a and/or Cigarette a br ing and of defect The p can more (sticks normal, causes radiation Some t hrough p physical be acid and ot her eat get can be enough as healt hy well may cigarettes, dr ugs intake, to are vitamins avoid medical alcohol foetus encouraged and amounts), (some her and be as look af ter recommended illegal dr ugs dangerous exercise, for get and an enough after correct the and and go to antenatal classes. condition Multiple births Unlike most a Multiple time. time. Most However, children animals, multiple triplets may (identical) be and Monozygotic Here of into a just one one egg two or are bir t hs normally when are sometimes born two twins, occur toget her. dizygotic or when and, Two only more two even sor ts give of bir t h babies are babies more twins to one born are rarely, occur: offspring at born four, t he at same toget her. ve or six monozygotic (non-identical). twins zygote one separate placenta identical by humans bir t hs balls may which is involved. sperm. is of Identical However, cells each have why t hey for before t heir are twins some it implants. own. known result reason, The identical t he fer tilisation embr yop two Monoz ygotic as from t he twins twins are divides may share genetically twins. 266 835292 CSEC HSB Unit B Topic 7.indd 266 08/01/2015 16:15 Reproduction Birth a b p Figure B.7.6.7 shortly afterwards formed when Dizygotic Here her two The are Women to help 1980s) two t he is t he have as have difculty conceive. as In two when groups one of egg cells. t he as was ill. is b) fertilised and Dizygotic t hese sor ts only bir t h to Maths one twins are skills may be a two eggs not t his from different relationship are For given as many dozen were sometimes two by born at reason between t he dizygotic twins. produced and dr ugs, babies or at as t he a ve could eventually weighing high as little or as 1–2 from and eggs The to kg. did improved, beneting six tended t hat treatment (1970s result. born babies have hormonal treatment embr yos techniques fer tility or who sexes. such extremely of siblings of a releases each genetic days t hat Nowadays The different early half babies under weight, ver y be mot her fer tilised, placentas. ovulating t he The are between sometimes many t hat mor tality Multiple separate bot h non-identical receiving q formed into involved. and can women sometimes are time as was extremely zygotes same who Multiple are fertilised twins t hem give are t he known t his infant eggs twins divides Dizygotic Consequently, wit h embryo same twins twins time. twins the twins at dizygotic same Monozygotic separate ovar y sperm. a) at be As a sur vive so t hat IVF once. trouble result were women (page 256), time. 3 births births T able are B.7.3.2 births shows Year data T otal T wins Triplets when on two or more babies multiple births in the numbers Quadruplets are USA born. in 1995, 2001 T win Triplet birth birth and 2007. Quadruplet and higher Quintuplets rate or rate per birth rate More per 100 000 1 000 total total births per 100 000 total births births 1995 96 736 4 551 365 57 24.8 116.7 10.8 2001 121 246 6 885 501 85 30.1 171.0 14.6 2007 138 961 5 967 369 91 32.2 138.2 10.7 267 835292 CSEC HSB Unit B Topic 7.indd 267 08/01/2015 16:15 Reproduction Birth 1 Calculate and 2 the What b Calculate percentage 4 Suggest 5 What extra data rates given in and the natal ups Breast in var ying correct t he feeding for of the the USA multiple births in of 2001 births in between changes in three advice twins between 1995 were the twins? USA in 2007 that the you table 1995 have was and 2007. described used to in question calculate the 3. birth columns? or use t he of mot her initial damage how impor tance t he to include on t hat and t he has It milk are to of to wean on checks t he her keeping how to vagina, baby t he to for t hat bot h t here knowledge onto baby care ensure and no about semi-solid warm herself is and t hen clean, regular breast feeding. sterilisers. is of so also by ar ticial it t he milk is of over a to t he are any t he must of note time met. correct t he child is t hat bottles, t he is can t hat t hat occur even to contract? of fed, milk protection or of her milk carbohydrate, balance addition, of so fat, breast advantage degree infection be impor tance protein, t hat a In major cer tain unclean made diet on balance Anot her gives use exact child prevents t he advice interesting changes needs given mot her’s t he temperature. feeding Beast in multiple shown uter us mot hers antibodies, B.7.6.8 in last will advice vitamins. breast caused t he and means nutritious and number feeding Expectant This not the gives from food, check births percentage change This vaccinations, solid the care care baby. bleeding of explanations natal t he in triplets. Describe Post Figure the 3 Post change 2007. a were p percentage t he so is t he sterile breast when unclean constituents t hat against is minerals milk and is rich diseases. bottle water, at t he in Breast feeding when t he up. Questions 1 What hormone 2 What is 3 State three 4 State two possible genetic 5 State two possible environmental 6 Where 7 Can 8 What the is causes possible the the uterus Where is it secreted? afterbirth? complications umbilical monozygotic is the cord twins chance of a be causes at the of birth causes attached of pair on different of end of pregnancy. defects. of birth defects. the foetus? sex? Explain dizygotic twins your being of answer. the same sex? 268 835292 CSEC HSB Unit B Topic 7.indd 268 08/01/2015 16:15 Reproduction B.7.7 Family Family planning Learning By Importance of family the end planning is making decisions about t he number and timing in a family. It is ver y impor tant for a number of be ● ● It is less expensive to explain have a smaller family. ● parents More time may can be wish to pursue devoted to a People may higher r isk not of want each c hildren having child if t he family is babies later wit h There may not be any suitable the importance of the advantages disadvantages in life bir t h as older defects, parents e.g. housing available for have Down’s a control methods of birth explain the small. principles a methods syndrome. ● ● you career. ● ● topic to: planning explain and Bot h this reasons. family ● of able of ● children outcomes planning should Family planning discuss biological of of the the different birth control issues related to family. abortion. ● Women a ● can plan can take t heir careers and make decisions when to star t family. Women education Several is not advantage organisations globally is t he Organisations Association, provide International in of interr upted t he star ting advice on Planned Caribbean, provide education by family as t he about and t heir family. planning. Parentood such information oppor tunities a The Federation Jamaica Family contraception and best known (IPPF). Planning ser vices for sterilisation. Methods of birth control Contraception means t he p prevention of pregnancy. Exactly Figure says when Must pregnancy soon later (see as star ts is a fer tilisation when page t he matter occurs. developing 255). Many of opinion. Most embr yo embr yos do Some people implants, not people t hink it into implant, t hink star ts or t he it about uter ine once star ts a B.7.7.1 ‘If Y ou This Want Control The to Chinese poster Prosper, Y ou Population’ as week lining implanted do not Key terms ! develop. t his No-one early knows what propor tion of embr yos do not develop from Contraception stage. prevents The following are t he various met hods of and Birth Abstention t he each dur ing t he The by her met hod taking days from couples for use wit hdrawal contains wit hdrawal a (see t his far t he t hat more work B.7.7.2). day for t he has he can t he man ejaculates. sperm t han contraception has opposite get t he ended the that fusion of sperm. control Prevention not – per iod changes in or of birth abortion. is t he intercourse only or days to contraception it. fer tile avoid reason once ve fer tilisation. decide t he best pregnant. man subsequent is have to wit hdrawing As her noticing couple ovulation will completing when and per iod of not out The woman t he or temperature woman’s met hod so of body estimated before met hod intercourse woman Figure af ter met hod vagina sexual her t he intercourse woman’s ‘spur t’ having cer vix ve elapsed Some not rhyt hm in time is mont h mucus have method methods by For – contraception. egg Natural Any conception ver y his penis ejaculates, spur ts. from t he This is t he rst why t he effective. 269 835292 CSEC HSB Unit B Topic 7.indd 269 08/01/2015 16:15 Family Reproduction planning uterus 36.8 C°/erutarepmeT vagina 36.7 36.6 NOITALUVO 36.5 36.4 36.3 36.2 36.1 36.0 rectum 10 cap for folded cap insertion over fitted cervix period safe for time/days intercourse p Figure B.7.7.4 Diaphragm or Figure Barrier Barrier The B.7.7.2 t hat it Graph met hods before vagina showing (see is a t hin Figure provides condoms prevent can in B.7 .7 .3). are t hat it pills women A that take container makes their pill for sure every and covering order An protection in woman’s body temperature eggs coming into contact. to which trap additional against t he Figure are B.7.7.3 A hormonal to this femidom implant The implant will to advised into the spontaneity of enter condom diseases love t he is (STIs). making and 3 Diagrams t he to show female how condom to put on which a condom women can inser t into The pill t he to (cap) is cer vix use a a dome-shaped and prevents spermicidal piece sperm cream to of r ubber from kill which reaching t he sperm t he (see covers egg. t he Women Figure B.7 .7 .4). methods contains t he hormones oestrogen and progestogen (an ar ticial woman’s of progesterone) and is of ten known as t he combined pill. Oestrogen release inhibits hormones is diaphragm form arm. t he transmitted man’s not vagina. Chemical fitted of t he do 5 entrance been over t hey day The B.7.7.6 so birth t he just rolled advantage sexually interr upts is sperm, 2 The has intercourse that p Figure for a 4 p safe split. 1 B.7.7.5 changes sperm latex intercourse Disadvantages control of methods condom penis Figure start period cap p p after menstrual FSH production from t he pituitar y gland so t hat no eggs mature blood (see Figure B.7 .7 .5). 270 835292 CSEC HSB Unit B Topic 7.indd 270 08/01/2015 16:15 Reproduction The pill works (progestogen-only par tly t he man’s egg from also by making sperm pill) t he cannot contains woman’s get progestogen, mucus t hrough. It also in t he works but cer vix by no oestrogen. t hicker, preventing so a It fer tilised vagina applicator uterus contraceptives be supplied planning t hat implanting. Hormone can Family as a do not have long-term to be taken implant in which t he form releases of t he pills. They hormone spermicide rectum into t he blood. Spermicide before is a cream, intercourse anot her met hod, (see Figure The intra-uterine uter us from in jelly order e.g. a or to foam kill which sperm. diaphragm, as is It on placed should its own into be it is t he used not vagina toget her ver y p Figure B.7.7.7 p Figure B.7.7.8 Applying a spermicide wit h reliable B.7 .7 .7). and device prevents implanting Surgical (IUD sperm (see coil) passing Figures is a small t hrough B.7 .7 .8 and piece and of plastic prevents a t hat ts fer tilised in t he egg B.7 .7 .9). methods For male sterilisation a vasectomy (male sterilisation) is a simple surgical procedure in which the two sperm ducts are cut and tied (see Figure B.7 .7 .10). For female sterilisation a surgical procedure takes place in which the two A midwife shows one oviducts are cut and tied (see Figure B.7 .7 .1 1). of Written Birth control Collect methods some family patients an intra-uterine device Activity leaets – and the pros other and cons information about birth control methods one and her planning. Y our local family planning clinic or local library type of IUD may uterus be able to provide information, but governmental Federation you use with the some. websites organisations, Y ou of such can also ofcial as the search online organisations International or for further well-known Planned non- Parenthood (IPPF). p Make a table to compare the advantages and disadvantages of the Figure B.7.7.9 intra-uterine methods of Emergency action as t he is birth control described contraception taken quickly. emergency intercourse. The unprotected pill. is One This second also must this chapter. available option option intercourse, in be is is have from a doctor morning-af ter taken to preferably t he wit hin t hree an tted IUD or a pharmacist pill, days also of wit hin An example of an different position in inserted by device, the a showing uterus once it its has been doctor if known unprotected ve days of sooner. Abortion Abor tion is a ver y controversial topic in t he Caribbean, as it is in many Key ot her t he in par ts of removal or caused t he world. An or expulsion by its complications deat h. during abor tion from An t he t he uter us abor tion pregnancy is or can can termination of an embr yo occur be of or a pregnancy foetus, spontaneously by term ! resulting due Abortion The embryo foetus. destruction of an to or induced. 271 835292 CSEC HSB Unit B Topic 7.indd 271 08/01/2015 16:15 Family Reproduction planning Spontaneous sperm cut tube and tied Abor tions occur miscarriage. t he embr yo t he foetus tube not has has from Induced p Figure B.7.7.10 is (see several implanted developed page 293 normally. being form of properly into cases t he for t he There chromosome bot h abor tion reasons normally. on In This possible is known It could be t hat lining so t hat t his. uterine may be a severe mutations) body has and as a genetic t he prevented foetus has abnormal born. abortions Vasectomy top oviduct are not not developed babies testis spontaneously. There abnormality sperm abortions ends end of Abor tions can hormones or be induced. This can be done eit her medically using surgically. Medical cut oviduct and blocked Medical taking abor tion t he involves abor tion hormones cause pill). t he t he This removal taking has of to t he of be hormones (sometimes performed pregnancy via early t he in known as pregnancy. vagina. There The are ovary two hormones t hat may be used. vagina Misoprostol causes contractions of the uter us like those that happen during uterus labour and birth. In fact, this hormone is also used to induce births. It is often used together with mifepristone (also known as RU-486) which rectum inhibits or blocks the action of progesterone that is needed to maintain pregnancy. RU-486 is also taken as an emergency contraceptive after p Figure (tubal B.7.7.11 Female sterilisation intercourse. Medical abortions are effective up to nine weeks into pregnancy. ligation) Surgical Surgical (in t he abor tion early Suction is a stages) weeks dr ug misoprostol is back t hen of wit h inser ted cer vix. to dilated to foetus t he abor tion This of of t hat t he A long, scrapes may be In countries where circumstances there is would terminated, physical or mother’s device and a it mental existing a and for is to a a the life into out is the t he rst taken woman called a cer vix a t he uter us lasts 10 –15 to suction be scraped of out rst t hrough from This 5 t he of t he t he the t he weeks dilated uter us. procedure uter us. A usually lasts hours. is than a out Af ter 12 –15 allowed in cer tain female’s is is minutes. the of her is cannula mother, there t he on to which circumstances result lies administered The of and speculum agree. so suction advanced). is enough, foetus abor tion more or The during suctioning. period more pain t he inser ted and is eit her recover. may doctors a wide to carried likelihood as is usually hours placenta impairments open placenta damaged; children procedure. hold by during instr ument anaest hetic knife is reduce is nal of to inser ted induced two strong an to recover y legal, performed cer vix few pregnancy pregnancy t he procedure lining, where is and t he dr ug local loop-shaped greatly there and t he procedure possible risk be foetus t he a The A used When inser ted wit h A is require, abor tion t he before stir r ups vagina. suction minutes, health t he of procedure taken in placenta. 10 when also feet (if period. instr ument suction gestation. cannula is removal scraping abor tion women surgical cer vix a and t he gestation her an by (widened). t he Instead t he open Then, connected or surgical 6 –12 her involves if the child large mental pregnancy being risk continuing include to the born the or physical was with health not severe of the pregnancy. 272 835292 CSEC HSB Unit B Topic 7.indd 272 08/01/2015 16:15 Reproduction As stated ver y earlier, strong of ten Family use abor tion opinions. when favour intention to made are When ● to help Many illegal medical safely. abor tion, t here have control over died and have t hem and view and make is is like consider to more by been people (and under ver y t he who is points following injured not now The will) t he The difcult have facilities easier deat hs. always do any not have. seriously appropriate it a having people cer tainly people repor ted t hem it not, many countries, fewer does people which may t he abor tions wit h people out have topic t hose t hat many some been book might not are This for carried in been of below beliefs what and do Since, always point you abor tions training controversial topic. rm discuss have abor tions t here eit her abor tion women ver y t his disregard you discussing having ● it a statements discussing circumstances, for is The to to it is topic. points. from a carr y have argument so planning is better out an t hat to have safe. The rights of the baby must be weighed against those of the mother. The mother may be physically and/or psychologically harmed. She, therefore, has the right to decide whether, or not, to have the child. Because no method of contraception is 100% effective, abortion will be necessar y. ● The bir t h of intolerable a child burden wit h on physical parents or mental leading to impairments t he child (and can t he place an parents) suffering. ● Unwanted children – with physical or mental impairments or not – may be neglected or abandoned. Problems will be created for society to deal with. ● In cer tain is does give not traumatic ● Some by ● t he t he Some only bir t h event people destroy ● circumstances, abor tion an to in have people women t he who use an her embr yo, or rape and cases, some humane unwanted child people solution, who will will so say t hat remind a t hat woman her of a life. rm belief foetus, hold abor tion met hods. Most view as abor tion t hat af ter t hese contraception religions e.g. practical life t his begins time is at conception. considered to be To murder beliefs. a met hod as of morally bir t h control rat her t han use wrong. Talk about ? ● Techniques, to be such detected whilst the as with foetus is chorionic the in villus possibility the sampling (CVS), remedial measures of allow to abnormalities be undertaken, womb. Ask two you know or abortion ● Fewer t han ten per cent of abor tions are carried out for reasons of Some people argue t hat t he majority are performed to have reasons and state t hat t his is t he easy way out. More, t hey will ● be done to improve t he quality of life of t he be child. on obvious present People wit h the mental, ● lives. Abor tions are psychological years later Any or physical, a abor ted impairments healt h scars. when risk foetus to t he Sometimes women feel will not can female t hese guilt do about have of ten and not t his lead may happy the your abortion to the should others. information not own Y ou about be may human and lead had to physical evident an abortion as contraception we previous few have done and on the and until many their pages and ask for responses. abor tion. Y ou ● for means oppor tunity. become having facilitator which reproduction, creative on discussion. argue, views should a who views for discussion social people different foetal Y ou impairment. three hold There is no method of contraception that is 100% effective. This means that should question decide for your even though they took precautions to prevent becoming pregnant, women as may get pregnant when they are unable to support a child. Abortion is a everywhere?’. ‘Should on a suitable discussion, abortion be such legalised way to ensure that an unwanted child is not brought into the world. 273 835292 CSEC HSB Unit B Topic 7.indd 273 08/01/2015 16:15 Family Reproduction planning Questions 1 State five 2 Which 3 Identify method the planning 4 methods Using the Give 6 Discuss 7 Which control. effective effectiveness terms types rhythm, 5 most birth of a at a preventing condom, b sexually an IUD transmitted and c the infections? pill as family methods. following a is of b three ‘barrier’, of reasons of the conception ‘surgical’ and ‘natural’, classify the contraception: vasectomy, whether ‘hormonal’, for c the combined women abortions methods of should birth (fertilisation), seeking but be to d condom have freely control before pill, and e a cap. abortions. available in your (contraception) country listed or not. operate(s) after implantation? Summary ● Sexual In reproduction humans There into in is fusion as happens plants. offspring ● Sperm and a are cells have small surface (23). a before The after The the of in a the from eggs are The eggs the ovary cycle about hormones FSH and stimulates the oestrogen. LH does the not During lining the vas gland and of penis the then seminal the of break one are a haploid 23 for fertilisation. are cells away parent eggs. divide as happens and adapted for energy. pathway number At the to the of developing front egg is cell chromosomes chromosomes. the swimming the The embryo reproductive dividing meiosis they much smaller potential at birth number at in by the After that to the are in the only The to become usually ovaries. activated chromosomes to of in pituitary and the the secrete an the and ovary coordinated ovulation, receive concentration eggs life. reduce numbers, occur are ovary luteum ready differentiate and of to are ovulation. changes secreted by Then, of the throughout changes eggs corpus state the gland. by FSH secretion pituitary of gland progesterone embryo. progesterone If and the which fertilisation decreases and down. sperm deferens into the in ovaries halve ovulation. a breaks ejaculation, along the stimulate of by nuclei. These are at uterus. number series occurs gametes instead provide digests numbers in only cells contains oviduct month. stimulates happen, uterus the that in to body is to the provide develop present the a that tubules the large into LH uterus in to that female clone. Sperm also the huge development to of divide is over the cell Eggs a a contains seminiferous swimming. menstrual LH in the mitochondria stores lining of there forming cells. the reproduction, parts (acrosome) egg sperm uterus maintains egg and nucleus each month, from than energy in or gametes and asexual identical (‘tail’) The of reproduction, enzymes of in bacteria, chromosomes for potential secretes ● of inside puberty. released gametes smaller produce number These ● are implants two sperm flagellum develop or fusion are asexual contains specialised one In nucleus testes cells the it the of membrane. The involves gametes genetically packet cytoplasm ● male no two many the pass into the vesicles vagina from the urethra, are during epididymides where added to where secretions make they from semen. the This are stored, prostate passes out intercourse. 274 835292 CSEC HSB Unit B Topic 7.indd 274 08/01/2015 16:15 Reproduction ● Family Sperm cells womb, into the occurs just before, sperm will surround of ● the After to the ● oxygen, The placenta its of an artery takes ● The and amniotic in mechanical There the are breaks the and ● Ante-natal and of ● their drinking feeding. mother followed alcohol. care and care their on is baby urea – of at by more is are given to that The nuclei continue oviduct the The with e.g. a lining of nutrients urea. sufficient materials large surface circulation minerals into the for fetal circulation. cord and which and a contains vein that advised and or temperature. the first second, head the stage the passes uterus mothers. about about mother the the shocks body During In of suspends any amnion through to deliver are given the stage. advice mothers core baby’s expectant and mothers at labour. the third warned of or that against contractions to are tissue intervals. and the given health cells Divisions give and the down maternal placenta foetus process intensify Mothers continue the irregular pregnancy the the fuse. waste, maternal the environment birth They to that embryo to the zygote. with umbilical connective its this is the the the a of ovulation implantation. other and the as travels adapted into by through embryo vitamins blood protects the and neck If foetus. keeps of health. Checks Post-natal and is acids, foetus layer This afterbirth about and the contract (prenatal) information aspects is the organ is the chance embryo. provide dioxide a gametes known stage which circulation amino the contractions This as to to thin stages the vagina. placenta a fluid. begins This is embryo developing deoxygenated blood is the foetal to is two is oviducts. pathway two-celled This which the there the egg a uterus. carbon dioxide a of multicellular vessels growth. glucose, damage three uterus its between brings sac the into cervix, into then digest fertilised This supply attached amniotic sperm blood away to the swim membranes divides of to intercourse the cells. carbon is that and and oxygenated foetus ● take oxygen, placenta so, lining through continue cell many grows exchange circulation, The and If zygote of the metabolism for diffusion ● into vagina after , the join ball contains and area egg. the hollow embeds the They just and gametes uterus for or an egg fertilisation, a from uterus. meet the two form and swim planning the about and their are diet, dangers the foetus of and carried Health support, other smoking importance are babies. given They their of breast out. checks e.g. with on breast feeding. ● Birth control includes abortion, ● There ● refers to any contraceptive the are natural removal four main method methods of an such prevent the prevent fertilisation embryo methods methods, to that of as or foetus birth of following a baby. This (conception) and fertilisation. contraception: the rhythm method and the cervical mucus method ● barrier and ● ● An the added Abortion surgical and is prevent methods: a of such sperm and eggs meeting, e.g. the condom sexually of hormonal using the the for birth or and is using that foetus. tubal that infections, control embryo men condom transmitted of methods contraceptive pills creams vasectomy of method removal as spermicide advantage transmission ● methods, implants surgical that diaphragm chemical or ● methods it such involves It is a ligation reduces as HIV either topic for the and women. chances gonorrhoea. medical that of or engenders much disagreement. ● Family many planning children gives they people will the opportunity to decide when and how have. 275 835292 CSEC HSB Unit B Topic 7.indd 275 08/01/2015 16:15 Practice Reproduction Questions 9 Practice Which is t he tubular organ between t he testes and t he Questions uret hra? Section 1 A vas B epididymis Which hormone stimulates t he repair of t he uter us af ter menstr uation? A Luteinising B Follicle hormone C seminal D ureter stimulating hormone A human Progesterone D Oestrogen of Which A 3 statement Ejaculation B Fusing C Embedding D Release Where of t he of does of best semen sperm of an describes t he into wit h t he embr yo ovum into fer tilisation in vagina. ovum. into t he a fer tilisation? t he t he uterine oviduct human t he vagina B oviduct C cer vix D uter us Which of contraception a diameter is most of 25 of mm. 0.1 mm. What is A t he drawing of an magnification drawing? ×2.5 B ×25 C ×250 D ×2500 tube). Section 1 occur? Data B on t he effective if age of cancers is analysed a Explain The met hod has diameter A table cancer, 4 a lining. (fallopian being has different A egg (FSH) egg C vesicle (LH) 10 2 deferens A to people is find what shows cer vical out is who collected who meant data on cancer is by diagnosed healt h at most t he t hree and are by risk term of in t he cancer This cancer. cancer cancers testicular wit h aut horities. [3] USA: breast collected used between 2007 and 201 1. The table shows correctly? ● A rhyt hm t he number and B of new cases each year of breast met hod cer vical cancers in women and of testicular condom cancer C t he D diaphragm in men pill ● t he percentages of new cases in different age groups. 5 Which is a barrier met hod of contraception? Percentage A Age B intra-uterine C spermicide device with group/ Which is tuberculosis B malaria D 7 disease A C newly type of diagnosed cancer Breast Cervical T esticular cancer cancer cancer condom < 6 people each (IUD) years D of vasectomy a sexually transmitted infection (STI)? 20 0.0 0.1 6.6 20–34 1.8 13.8 48.9 35–44 9.3 24.9 23.8 45–54 22.0 24.3 13.5 55–64 25.5 17.6 5.1 65–74 21.3 10.7 1.3 75–84 14.4 5.9 0.6 syphilis influenza The placenta exchange of provides a substances large surface between area for maternal t he blood > and foetal blood. Which is transferred from foetus 85 5.7 2.7 0.2 T otal 100 100 100 to mot her? A carbon B oxygen number dioxide new per C amino D antibodies of What occurs A growt h B release b Which at (women 5.6 only) (men only) of of an an embedding age of t he groups are cancers most shown at in risk t he of developing table? [3] ovulation? egg in a Use t he egg of accumulation from an of data in t he table to explain how information follicle and D 7.8 only) acids c C (women 100 000 each 8 124.6 cases an embr yo fluid advice on cancers should be targeted. [3] ovar y in inside t he a Healt h aut horities encourage women babies. One advantages to breastfeed t heir uter us of t he of breastfeeding is t hat it follicle lowers t he risks d State e Describe to two lower table. of cancers ot her ot her deat h in women. advantages steps rates t hat from of breastfeeding. healt h t he aut horities t hree cancers [2] can in take t he [4] 276 835292 CSEC HSB Unit B Topic 7.indd 276 08/01/2015 16:15 Reproduction 2 a Practice Describe t he b t he process sperm. Two met hods met hods i) of fer tilisation of t he ovum 4 by The [3] and ● of contraception surgical Explain t he are hormonal ● met hods. biological ● basis of each of placenta about 50 all t he contraceptive t he met hods. advantages t hese disadvantages two Describe met hods t hree of effects contraception. t hat cigarette ii) have Explain on why t he it is ever y State t hree development impor tant of t hat a in 3 a State one in should function reproductive i) t he have sufficient Name t hat t he c The [2] of par t iv) ii) t he t he of foetus. umbilical umbilical in t he composition ar ter y and t he of t he umbilical [3] Explain how enables t he each of t he features listed above [3] placenta to function efficiently for t he pregnant calcium t he t he epididymis, scrotum. endocrine control testes. diet. each t he of t he foetus. [6] and Describe t he process of bir t h. [6] male system. testis, gland, b t heir microvilli t hrough [4] c iron in flows minute. differences t he development women blood smoke b may capillaries covered of vein. i) features: [3] and blood c of cells foetal following t hese a Discuss t he km epit helial ar ter y ii) has Questions gland activity of t hat t he iii) t he prostate [4] secretes ovaries hormones and t he [1] diagram shows a foetus wit hin t he uter us. foetus umbilical cord B placenta mucus plug in cervix i) ii) d Name A and Describe Explain t he pregnant t he B. [2] role impor tance women. of of B. [3] antenatal care for [5] 277 835292 CSEC HSB Unit B Topic 7.indd 277 08/01/2015 16:15 Unit C Heredity and variation C.1 Learning By the end outcomes of this topic C.1 Chromosomes be able genes define the terms DNA is t he is passing all t he of features differences from t hat one t here generation are wit hin to t he next. individual species and chromosomes between ● chromosomes genes Variation and and to: Heredity ● genes you DNA, should and explain the species. Humans differ from one anot her because of t he difference genes between different diploid and t hey inherit and t he environment t hat t hey live in. haploid Cells behave t he way t hey do because of t he enzymes t hey contain. These cells enzymes ● describe how determine sex define term instr uctions specic the of proteins. Each protein in a cell is made according in a sequence. gene codes Genes are for assembling made amino of DNA and Figure C.1.3 shows each acids gene toget her is a small in a section genotype of and made chromosomes to ● are t he DNA in a chromosome. a pair of chromosomes phenotype from a shows 23 human all pairs t he of cell. Chromosomes chromosomes chromosomes in are found from one each nucleus. wit hin nucleus: it nuclei; shows Figure t hat we C.1.2 have haemoglobin insulin a p Figure chromosomes showing that Figure C.1.1 worker is from of This cultivating amniotic fluid chromosomal (number laboratory of cells for p Figure 22 taken C.1.2 pairs of females screening in abnormalities total human karyotype. chromosomes. have in The XX. each That Males makes 46 There have XY of are a and occur in by plasma (see genes pairs. haemoglobin, human chromosomes cell characteristics controlled that protein Homologous (partner) are p C.1.3 plasma protein Genes insulin are on chromosome 11 Figure and C.1.2) chromosomes) Diploid Diploid – and a cell chromosomes Haploid – (written as The 23 a genetic t hey Human t hey in which (written cell in cells t he as which nucleus contains two complete sets of 2n). t he nucleus contains one set of chromosomes n). different t hat haploid information contain egg needed chromosomes. cells contain two and one copies sperm copy of to Human of body each cells each control of a human cells t hese (gametes) body diploid. is haploid. totalling carried This chromosomes, are chromosome, are This in means totalling means 46. t hat 23. 278 835292 CSEC HSB Unit C.indd 278 08/01/2015 16:17 Heredity and variation Homologous str uctural Chromosomes chromosomes features. They are also a pair have of t he chromosomes same wit h similar cell and surface genes centromere membrane genes. nuclear To understand t his, imagine what happens during sexual reproduction membrane (Figure C.1.5): human one egg cell, chromosomes, containing fuses wit h a one sperm copy cell of t hat each also of t he 23 contains (envelope) one chromosome copy of each has two t he sperm of copies t he of 23 human each chromosomes. chromosome, one The from fer tilised t he egg cell egg cell now and one from cell. Diploid Mother Father Mother Father 2n 2n 46 46 p Parents Meiosis Figure Haploid cell C.1.4 Diploid and haploid cell cells Meiosis or Types of n n 23 23 gametes Offspring 2n 46 (children) p Figure During C.1.5 development, containing obtains egg an cell. have Diploid Sex Sex millions exact Thus, two Figure Maintenance all copies is t he of t his of copy of of number fer tilised cells. t he body each represented diploid During egg cell each chromosomes cells in a divides cell present human to form division, are in a each t he foetus of t hese original genetically cells fer tilised identical and chromosome. as 2n and haploid is represented as n, as shown in C.1.5. determination determination different is t he chromosomes determination in males and of a person’s sex based on t he father mother females. × XY Except for human gametes cells and red blood cells (which lack a nucleus), XX all contain: + ● ● 22 1 pairs pair of of chromosomes, sex which are known as X gametes autosomes Y X chromosomes. female Female humans have 22 pairs of autosomes and two X gametes chromosomes. X Male humans smaller Y have 22 pairs of autosomes, one X chromosome and a chromosome. X XX Y XY We must use symbols to show whole chromosomes. We do not need male gametes to show the autosomes, only the sex chromosomes are important. Consequently, we represent a female as XX and a male as XY. Note that males are the exception to the rule that homologous “partner” chromosomes are identical (see Figure C.1.6). children XX Ratio Figure C.1.6 males born. knows why shows t hat In t here fact t his is t he t here are case. should more be boys equal t han numbers girls but of no females one 50% XY female : 50 male and really p Figure C.1.6 How the sex of an embryo is determined 279 835292 CSEC HSB Unit C.indd 279 08/01/2015 16:17 Heredity Mitosis The q X and T able Y chromosomes C.1.1 Comparison of are X and Feature X Length Long Genes for determining compared Y in Table chromosomes Y chromosome Short not contain these genes Possesses maleness testes sex Genes for controlling other Possesses characters variation C.1.1. chromosome Does and genes to hormones Possess many controlling control other genes that develop a to few and be produced genes features cause male that other than sex characteristics p Figure C.1.7 The chromosomes X seen and Phenotype and genotype The physical ot her features The human such as hair. It or phenotype facial features, × 20 an organism all t he height, shape of are known characteristics ears, skin as its phenotype. t hat we can colour and see, colour of Y under an also includes all t he internal features of anatomy, physiology and electron biochemistr y microscope of includes t hat we cannot see. An example of one of t hese aspects of 000 your The phenotype phenotype environment for all t he forms, more a, so or is in genes your t hat of are we we one characteristics. about blood inuenced which alleles, genotypes more is The a in t he The It is small alleles usually genotypes by live. have. or group. more t hat in we inherit genotype usual number are given genes term of to use genes represented symbols is by rat her and used it to t hat in t he a wide describe control symbols, t han t he one such words. sense as or A There and is C.5. Questions 1 What are 2 What is chromosomes? a the diploid, and b the haploid number in the cells in FigureC.1.4. 3 State a human 4 State the 5 Describe 6 Explain Learning By the end outcomes of this topic C.2 be able describe explain the mitosis a a your is between determined the chromosome. two in humans. t he nucleus human Y ou sex chromosomes. should use a diagram to answer. division cell full can set divide of into two, chromosomes. Wit hout must any divide so chromosomes t hat a each cell will cell give any importance in sur vive reproduction long and Also any cer tainly of cell t hat will does not not be able gain a to full divide set of to 46 chromosomes and does replacement for cells. growth, daughter asexual sex “partner” mitosis not of differences for chromosomes. you gains ● term no to: Before ● the has Mitosis Nuclear should that biological how illustrate cell not sur vive eit her. Cell division occurs when t he nucleus divides by cells. one ● ● of two processes: mitosis meiosis. 280 835292 CSEC HSB Unit C.indd 280 08/01/2015 16:17 Heredity Mitosis and is variation t he type chromosomes. daughter involves t hat cells t he each identical of nuclear t he have parent diploid movement new to If Mitosis cell t he has of a has nuclei. t he full original division cell a t hat maintains diploid Mitosis is a chromosomes. number (parent) of t he number, division The number t hen of t he t he and is ✔ nucleus movements chromosomes of two make Study tip and sure genetically Before in the mitosis can start, chromosomes that each two molecules is chromosome the DNA copied so consists of cell. enough DNA of for DNA. the This two gives new cells. Mitosis Mitosis is a produced present occurs by in in growt h type cell mitosis t he t he is of contain parent body division cell cells, a t hat copy (Figure produces of ever y C.2.3). par ticularly cells. chromosome This when identical type cells of are cell to was division replaced or follicles growth – t hat cells when occurring. hair airways The replace of – for hair ciliated epithelium Malpighian skin cells alimentary replace canal – – to in the – to produce follicle uterus cells In the one and It is We cell t here stage of is in a no You compare it t he C.2.4 to all Figure you draw four of t he shows see to over the body t hat what after menstruation ends of by white produce repair – to cells to dividing stem t hem as cells of a the the lining long growth mitosis can see in a to all t his because So into function happen all! 46 divides for you to replace in cell instead, it While body, 46 the C.2.2. divides chromosomes have t he cells. the Figure when t he we two in by in a chromosomes diagrams of each chromosomes. chromosomes stages cell happens like t he some t he a specialised divide, diagram to see all when changes show show to cells become ability place can to simple easier Figure occurs. shows stem to – and and die happens the cannot mitosis much cells. are out mitosis retains C.2.3 mitosis. human worn differentiates cell Figure There get body, cell other C.2.1 that – red cells bones cells epidermis marrow blood Figure the epithelium replace p in dead to bone ovary layer replace from in plant t he mitosis tip in cells of t his a t han root it is where photograph in animal growt h if you C.2.3. 281 835292 CSEC HSB Unit C.indd 281 08/01/2015 16:17 Heredity Mitosis 2n = 4 in this Non-dividing and cell cell chromosomes a invisible; cell variation builds up an line stem supply and the mitochondria, of energy organelles, cells e.g. mitosis replicate nucleolus Early Stage 1 chromosomes mitosis developing appear due to coiling, which nuclear makes them replicate fatter, and envelope red blood cells centrioles move to opposite centromere poles centrioles Late Stage 1 mitosis chromosomes chromatid become shorter chromatids spindle now centrioles visible apparatus has at a pole now mature developed blood Stage 2 chromosomes arrange themselves on cells equator the equator p nuclear envelope Figure One other retains The 3 the move to of spindle chromatids the poles 4 The reach the by C.2.5 cells to form two specialised daughter while the ability shows were a to be a stem the human st ained wit h t hrough a cell cell a dividing uorescent laser by mitosis. st ain microscope. and Here t hen you can see cell – how t hey extensive are st ained red. Mitosis is have st ained t he spindle impor tant t he diploid g reen. as it The bres are wit hin makes number of c hromosomes t he sure t hat all t he are cells: chromosomes chromatids poles ● are genetically cells and occurs Growt h such diploid mitosis becomes fibre ● envelope by and contraction Mitosis Two divide fibres ● Stage cells differentiates photog raphed spindle the Stem cell disappears Figure Stage C.2.2 cells. as identical. during happens t he end growt h, all of over bones repair t he and body, where it replacement. but is t here are places concentrated. nuclear nucleolus ● When wounds heal, new cells are produced by mitosis reappear to spindle fibres disappear the starts to ● cell across the replace Skin cells t hose are the divides, divides off damaged. stem cells in t he t he surface Malpighian divide by mitosis layer of to at t he form t he body; base of t he replacement cells nucleus the to Figure Red blood B.5.5.1 on page 194). two ● daughter (see cytoplasm form genetically cells live for about 6 weeks and are t hen identical cells chromosomes and the destroyed Figure in t he liver. Stem cells in t he bone marrow uncoil divide p r ubbed were divide equator epidermis After t hat C.2.3 The stages of mitosis ● The by mitosis lining of t he menstr uation; repair t he lining grows to uter us t he lining produce stem and is new shed cells replace in red ever y t he t hese blood cells. mont h uter us cells at divide when to t he again. 282 835292 CSEC HSB Unit C.indd 282 08/01/2015 16:17 Heredity and Identical by twins mitosis Figure variation to B.7 .6.7 identical possible are form on twins. to do Mitosis formed from a of group page They t his 267). are t he cells These clones process same t hat fer tilised splits into grow inside t hey are as ar ticially to egg. two t he uter us genetically produce This divides groups to (see identical. clones of ✔ Study tip become It animals The is such as important from Figure chromosome cattle, sheep and goats. It is illegal to do t his wit h reproduction genetically identical by Asexual mitosis. common they do in not plants use involves to fungi. mitosis as production parent. reproduction and Practical Modelling their the does Note they This do is not that not of individuals because happen bacteria have is has to take that two each identical humans. chromatids. Asexual point C.2.3 the in cells most or are are in produced animals, reproduce nuclei that but asexually, chromosomes is ours. 3 daughter These so that cells information Imagine but like stage in this separate each has that all of the chromosome. happening chromosomes in the genetic your for all stem 46 cells. Activity chromosomes Requirements ● A suitable of knitting coloured ● A circle circle material wool to make about 80 in of chromosomes, length or e.g. pipecleaners short for lengths modelling or wire. drawn on a as as possible. is models mm big large piece It of paper, e.g. represents the A3 size. Make sure this cell. p Y ou need at least eight lengths of knitting wool or eight Figure the preferably four of one colour (e.g. blue) and four of C.2.4 another colour root tip The instructions will assume you have pipecleaners. Y ou could 1 T ake two of the red on 2 the Now them paper. fix a appear at at random T ake second a and the in of two start the or to model blue of of of “double-stranded” chromosomes stage 1 sure of mitosis. double-stranded chromosomes. Move in Make your stage 2 sequence The blue two mitosis across to (see your the are of make a sketch as they and known the centre of Figure C.2.3). Y ou the of how how have they At the beginning of See in the as they arrange to break part you have each so pulled 5 chromosome apart Complete to your chromosomes each 3 the two now you 6 The chromatids will arrange poles model mitosis they the this red stage. appear them in any in each chromosome Figure by have to separate the two of appear of in them the by so they look as if they C.2.5 mitosis. A The fluorescent human cell cell has dividing been markers so stained that you stands are see chromosomes in red and the being spindle fibres in green. are structures The blue dots cell. arranging stage 4 and the cell full of catalase “single-stranded” then draw a nucleus around group. cell now stranded” then and opposite as identify of can of can “cell”. stage apart, you to later so at if stages appear. with begin from C.2.3). p 4 cells drawn double-stranded “cell” of undergoing the chromosomes identical onion sketches. Figure you chromatids can is (see appear are two as This that model colours pencil mitosis “cell” your chromosomes strands chromosomes of that 1 your make each or pipecleaners. stage centre photograph pipecleaner your make two 3 stages pipecleaners chromosomes Position different an take different photographs of (e.g. mitosis. red). Photograph pipecleaners, the divides into chromosomes. DNA in these “double-stranded” two If daughter the cells daughter chromosomes chromosomes is each cells are replicated with four going to (copied) “single- divide to again make again. 283 835292 CSEC HSB Unit C.indd 283 08/01/2015 16:17 Heredity Meiosis Improve your model chromosomes each Do stage not and forget making use to some to apart. show Y ou them make a the can to centrioles make make record of a a and model to the spindle show how and bres the variation that cell pull the appears at poster. your model by taking photographs or drawings. Questions 1 Mitosis occurs happening p Figure make C.2.6 good Modelling material for pipecleaners showing 2 Explain why. Mitosis is of A it Learning end be outcomes of this able topic you C.3 ● describe explain the of sperm female cells in gametes replacement of cells the in in testes, the the girl in body but it Figure and the is not C.2.1. Name four places in the body where this occurs and repair explain meiosis the meiosis necessary. cell divides happened to to the form DNA two in new the diploid original cells. cell Suggest before it what must can start mitosis. each pair of Meiosis Meiosis cells produced chromosomes in meiosis present in t he contain parent only cell one (see copy Figures of C.1.4 and C.3.1). importance The of in of to: The ● is diploid have the formation mitosis 3 should the formation involved tissues. why By in the the of stages in in reason why we need to have meiosis is clear from Figure C.3.1. sexual reproduction. cell 46 in cell 46 ovary in testis meiosis 23 23 egg 23 sperm 23 fertilisation 46 ✔ Study tip p Figure C.3.1 number Meiosis is important reproduction as chromosome it in The role one generation of meiosis to in the maintaining next in the sexual chromosome reproduction sexual halves number from zygote Meiosis the and it causes parent actually involves two divisions of t he nucleus and cytoplasm of t he cell: variation. ● rst division (meiosis chromosomes ● second division chromosome Random Apar t of – separates (meiosis II) t he members of each pair of chromosomes) – separates t he two copies of each individual (chromatids). assortment from feature I) (homologous t he halving meiosis chromosomes is from in t hat one number it of chromosomes, introduces generation to variation. t he next t he ot her Effectively when it impor tant “shufes” organisms t he reproduce sexually. Inside all inherited t he cells from of your your body fat her and t here are copies of copies of t he chromosomes chromosomes you you inherited from 284 835292 CSEC HSB Unit C.indd 284 08/01/2015 16:17 Heredity and variation Meiosis Meiosis the diploid cell is (2n) number of is two divisions. Division 1 separates partner Division 2 separates chromatids chromosomes Early this Stage 1: chromosomes 4 Start Non-dividing of Division appear 1 cell: chromosomes invisible; nucleolus cell builds supply e.g. up and an the energy organelles, mitochondria, replicate Mid Stage centrioles move Late Stage to partner chromatids their chromosomes the pair with and poles has where exchange opposite 1: crossing-over occurred 1: replicate break up and genetic chromatids material become visible partners Chiasma: crossing position over where spindle occurs apparatus is now visible Stage the 2: partner align Stage chromosomes themselves on equator nuclear envelope Two and opposite poles move by to contraction and spindle fibres disappear haploid cells Stage Start chromosomes themselves the chromosomes separate of nucleolus 3: partner the of Division 4: the cell the equator now divides across 2 align chromosomes along move equator to opposite contraction of the poles by spindle fibres the cells along divide the equator parental combination These will p Figure C.3.2 be cells are the produced. parental recombinants gametes Note also, and are that variation haploid. On has fertilisation occurred due the to diploid crossing combination state over. Meiosis 285 835292 CSEC HSB Unit C.indd 285 08/01/2015 16:17 Heredity Meiosis your ✔ Study ever tip mot her. since When Look at the human karyotype They t hey meiosis C.1.2 on page 278. occurs that the in pairs maternal paternal in in – gamete at for many generations of cells fer tilisation. are shufed so formation, t hat each t hese paternal gamete has a and mixture. maternal P6, where So, may have M1, P2, M3, M4, M5, etc. M = e.g, a maternal, chromosomes P are in unchanged toget her This gamete shows remained came variation in chromosomes Figure have rst and one origin origin. of each and the pair = paternal and t he number represents t he number given to t he is other is chromosome. (X and an X Y) and in or meiosis a pairs division. maternal and haploid Figure in cell C.3.3 A An and par ts called Unit up randomly effect of cells. to Some t he sex gametes is on t he t hat as equator t he you of gametes chromosomes receive can see t he cell in Figure haploid as at the B. Their you arrangement can random see in of the two arrangement the haploid cells pairs gives after of cell receive cell of event DNA over Figure t hat can between and C.3.4 is shows The of diagram meiosis paternal maternal chromosome chromosome C.3.4 Crossing occur in during par tner an chromosomes. Figure t his chromosomes homologous p sperm happens A Look in crossing C.4). what eit her a the t he rst of C.3.3. B cells homologous two in mixture different chromosomes combinations two divisions of t he exchanging of meiosis over impor tant small is cells chromosomes Crossing produce line The paternal cell p to example Y. Chromosome meiotic Anot her impor tant t he Figure meiosis (homologous) result C.3.7 source of t his does of is chromosomes. genetic process not show in variation a any single of This pair crossing is (see of over. over 286 835292 CSEC HSB Unit C.indd 286 08/01/2015 16:17 Heredity and variation Meiosis Practical Modelling activity chromosomes Requirements ● A suitable of knitting coloured ● A circle circle Label is your material wool on a as possible. big piece Do forget the of to wool sticky take red Now (see that sketch of fix 4 appear Figure C.3.2). have drawn appear. second of the so pipe first you pipe e.g. cleaners e.g. A3 size. cleaners indicate to paternal of short for lengths modelling or the Make sure this cell. which chromosomes. each crossing over. the are Y ou the can maternal do this by chromatid. different there “M” red in stages of your model or are two but 2 divide them paper. each meiosis. so that we will in of your so at cleaners. of 1 a your as of the random T ake This first in the blue how centre or of of your make chromosomes appear sure is division photograph model they Make they they division which you that in the the a to middle colours chromosomes the together. that are of can towards towards the pair assume that first facing facing movement and to pipe stage double-stranded the chromosomes the of pairs of ways “M”chromosomes the of of are and two chromosomes. occurs, stage blue start chromosomes two chromosome as on division have two the cleaner chromosomes over division or paper, Position they your Model chromosomes, the and at you crossing both of around cleaners 1 that of length represents the how a equator 5 tape stage Move It pipe are “double-stranded” Move piece photographs pipe double-stranded 3 or make identical in sketches. two “cell” large which chromosomes meiosis 2 of and piece pencil T ake models mm as a 1 80 drawn putting not make wire. chromosomes make to about a the same at this along Y ou the pole or is that no the should pairs stage there – find with with “P” and pole. apart into is division line meiosis. same cell in It this arrange chromosomes imaginary in two. as in What stage has 3 of the happened first to p the number of Figure C.3.5 Models chromosomes 6 Model the movement of meiosis shown the chromosomes as happens in the of the the way modelling Why is it division Y ou can your by chromosomes activity essential of in that Unit the in Figure behave? C.2 (page If C.3.2. you What are not do you sure notice look late two stage pairs 1 of of the back division of meiosis about to the 283). chromosomes form pairs in stage 1 of the rst meiosis? make models taking as at second first division of chromosomes? a to model make a photographs to show poster. or how Do making the not cell forget some appears at to a make each stage record of and your use model drawings. 287 835292 CSEC HSB Unit C.indd 287 08/01/2015 16:17 Heredity Meiosis Written Comparing It is easy help you mitosis with to get to remember confused meiosis between how they these are two similar types to each cell nuclear and division. how they A diagram are to compare them and a table will different. parent cell (contains become pairs of other Meiosis chromosomes two variation activity Mitosis parent and visible (contains pairs each chromosome been duplicated to form of two homologous nuclear has two of chromatids envelope homologous chromosomes) chromosomes) chromosome chromosomes become each chromosome visible has chromatid been duplicated form two to chromatids centromere homologous (partner) chromosomes and the nuclear chromosomes envelope the disappears centre cell of lie homologous along move the chromosomes and the cell equator) are equator after opposite division, line up on equator second along into the two a time to chromatids and move cells four daughter which half the identical to Read C.3.7 over the of Comparison past ● number cells ● chromosome ● genetic few between pages and mitosis make as the of parent crossing over may cell have Figure cells number the cell; parent p poles are chromosomes reappears separate opposite daughter contain envelope now to equator the nuclear the for two begins divide the chromosomes poles cell up divides separate to pair on the separated and lie on (equator) chromatids then and a occurred meiosis table to compare mitosis with meiosis. Here are three features to start with: produced number differences in daughter between cells daughter of humans cells. Questions 1 Where, 3 How 4 Which 5 Explain 6 State in the many cells human the three human will cells body, be are importance ways in does meiosis produced if a take single place? cell divides by meiosis? haploid? of which meiosis. meiosis differs from mitosis. 288 835292 CSEC HSB Unit C.indd 288 08/01/2015 16:17 Heredity C.4 and Variation Variation Variation species. are variation is All t he t he different Learning phenotypic organisms from one differences wit hin anot her, a in between single, ot her individuals sexually words wit hin reproducing t here is By a species variation in ● These differences environmental may conditions, e.g. be due end be of this able genes inherited from t he diet parent, e.g. genes for growt h explain the difference between inherited (genetic) and non-inherited explain is If you of study human simple ● a group features of people, t hat is groups, a group blood Genetic There are you can controlled obser ve by genes variation and are in a sex list are (see group (see long but many in a t he (see Figure of case t he C.1.6 human controlled study case on study page features by on genes a on 129) page 261) 279). t hat in page are more easier to complex study way t han t han t he blood described text books, e.g some people can roll t heir tongue like t he girl Figure C.4.1 C.4.2 and some cannot. This is an example of variation but genetic individuals. In is the this differences chapter you not can simple Variation in between Figure variation important. number inherited p in genetic variation blood Rhesus ● why way. ABO ● variation rate. ● Inherited you to: (environmental) ● topic to: any ● population. the should outcomes investigate the variation among the inheritance. people around Figure C.4.2 you 70 60 50 ycneuqerF 40 30 20 10 0 Tongue p Figure C.4.3 A roller bar chart Discontinuous Discontinuous t he A feature such of There no in a is as in is results human a small discontinuous variation. Discontinuous variation t here wit hin ABO gradation in the where question phenotypes: smoot h result show roller of an investigation into tongue rolling variation t he discrete feature to variation characteristic number Non-tongue a blood group between number usually are of clearly dened differences in population. group A, blood B, when types, an shows group groups. distinct occurs system group AB a small and group Where t he we t his call individual O. differences feature is p controlled by just one or two genes as we will see in Chapter C.5. like Can you roll your tongue this? 289 835292 CSEC HSB Unit C.indd 289 08/01/2015 16:17 Heredity Variation Practical Study ✔ you are more rolling often interested about variation, the such and eye used as genetics in examples as of earlobes, colour, that examples search human by online genetics” University John of H. variation Requirements ● graph and paper 1 Choose are of for human tongue human some suitable features that you can record read McDonald class or from another class or from among your Make a forms of table up the the Calculate groups, 4 10 13 21 14 15 7 Use the 16 in which first to feature record you the have number chosen. of people The who easiest show way to the do different this totals. the e.g. your data Investigate present tongue C.4.4 extend your T o measure a as far as hand from furthest edge extent of of plot a try collect people and bar to in data your non-tongue chart, like program from sample This at makes least that 20 are in it is to easy to people. the various roller. the one in and use it Figure to C.4.3. make the Y ou bar could chart enter for you. more results as features bar that show discontinuous variation and charts. variation span variation is where t here is a complete range of forms in t he possible characteristic measure roller of spreadsheet some your Continuous hand to a Continuous Figure should percentage data into Y ou 5. 6 4 the of Delaware. 3 to members the add and the friends. the of = p for “myths 2 article Activity learning your of variation tip Discontinuous If and little your in question wit hin a population. finger thumb Features of humans that show continuous variation that you can measure are: ● 40 males height ● body mass 30 ● lengt h ycneuqerf ● hand of forenger span. 20 Data for t hen used continuous to make variation a is histogram collected as shown into in a table Figure or spreadsheet C.4.5. A feature and such 10 as is human called a height follows normal t he pattern shown distribution. Alt hough is not always t he Where t he differences in t he Figure graph C.4.6. in This Figure pattern C.4.6 is 0 symmetrical, 170 190 210 230 handspan 250 t his case and t he graph may be skewed as in 270 Figure width/mm we C.4.7 . call t his continuous in a feature show a smoot h gradation, variation. 40 Continuous variation usually occurs when an individual feature is females controlled by a number of genes; it is polygenic. 30 ycneuqerf Practical 20 Continuous Activity variation 10 Requirements 0 170 190 210 handspan p Figure the C.4.5 results variation female in of 230 250 ● a metre ● a tape ● a set As some rule 270 measure width/mm T wo an histograms investigation hand students span in male to of scales – preferably digital with weights in kg show people are sensitive about their height and weight you might be into and advised to use to for choose this other features, such as hand span and length of forenger, investigation. 290 835292 CSEC HSB Unit C.indd 290 08/01/2015 16:17 Heredity 1 and T ake and variation the measurements height Record 3 Organise Do 4 the well the the i.e. not Divide as all the the use a so it a into in tally in or on order – between people. Y ou can collect the weight a spreadsheet. smallest the to smallest largest. Calculate number and the the largest. unit. classes, like 20 features. the Figure table least table is include range histograms can in difference to at other results data forget as of ycneuqerF 2 range, Variation e.g. 170 –189 C.4.5. Y ou this organise to should mm, 190 –209 have your at least mm, five etc. as classes. in Y ou data: Height Size class / mm Number T otal p frequency 210 5 – 229 Count /// up how percentages Our effects. Much This inherited as a of many human type of are in food variation is Impor tant – each histogram people is t he not Convert those effects result do on of inherited causes who class. like in the Figure results grow to t heir over weight ● ● quality of diet likely to social t he to ● are exercise are ● t he way t hese and is we grow have stature; children have normal interactions being near the normal of the mean distribution population height environmental known as non- are: not Height people receive who enough have too food much are are who do not have enough D adult males/m unlikely likely vitamin of to be Figure in C.4.7 skewed with A distribution most of the that is population tall t heir rickets – t he body – most being activity language(s) (if more mass t hese people and have speak active have many and people t he a are more effects type more muscular on of t he human religion likely t hey physique variation, t hat t hey e.g. belong any) exposure on – to A with and obese food and develop ● or full C.4.6 curve into p to Figure C.4.5. variation impor tant variation variation. quantity people plot has males/m 3 environmental environment develop. ● of adult ycneuqerF Causes many and of Percentage to disease properly; – children diseases who such as are of ten polio sick have do had not grow signicant and effects children climate – exposure to t he sun causes take good t he skin to darken in light-skinned people ● behaviour neglect Many people Income clean – some people care of t heir appearance and ot hers it. would levels water, Causes also add income determine t he access sanitation, of education genetic as an t hat and impor tant families medical have factor to a to t his healt hy list. diet, facilities. variation p Figure 3 Genetic differences between t he organisms in a population are caused can random assor tment of chromosomes during t he rst division of old. These identical Researchers twins who are follow by: the ● C.4.8 months development find out of about twins like these environmental meiosis variation (Figure C.3.3) 291 835292 CSEC HSB Unit C.indd 291 08/01/2015 16:17 Heredity Variation ● random anot her 50% chance female so ● fer tilisation, wit h t he and crossing were ● mutation whole – a 50% is over linked we t hat a baby as pure wit h zygote chance male during change chromosome in a determines determination inherit t hat t he an X zygote which of sex gamete where chromosome will inherit a variation so Y fuses t here t he is baby a is chromosome C.1.6) meiosis on chance t he will (Figure toget her a i.e. saw and which single eit her a can separate chromosome single (chromosome gene t he alleles (Figure (gene of genes t hat C.3.4) mutation) or in a mutation). Mutations A mutation occurs when there is any change in the amount or arrangement of DNA in a cell which alters a characteristic. There are two types of mutation: ● gene – any change in t he arrangement of DNA in a gene which alters a characteristic ● chromosomal – any t he Gene A is a lengt h 278). called is a A rats Human The str ucture of a of DNA t hat number of chromosomes in a cell or chromosome. a are for in to mutations ot hers, used susceptible rat to t he t he mutate exposed over commonly t hat genes are Most advantage codes change All organisms chemicals. an warfarin, over t he mutation. if cer tain organism to in spontaneous gene increased and to change mutations gene (page change any at a are e.g. a of a of t his DNA rate but t his sequence ver y low mutagens, such harmful, mutation poison, t he production base gives its but as single is rate radiation some giving protein a possessor give rat an t he resistance advantage poison. mutations majority albinism. of mutations Some mutant Huntington’s disease deterioration of t he result alleles which is ner vous in are a recessive alleles, dominant, late onset e.g. e.g. t he condition t he allele alleles causing causing involving a gradual system. Albinism Albinism in p Figure C.4.9 Albino twins from T anzania t he is a skin. pigment in condition The t he person disease Huntington’s disease as middle age, had (HD) Huntington’s usually person skin lacks and t he hair pigment along wit h melanin a lack of is a serious chorea. when The people neurological symptoms are in t heir do disorder t hat used 40s not or begin 50s and to to appear have be until already children. HD is but gradually a progressive The inherits allele who t he have cer tain t he t hat develop if disease deteriorates t hemselves. will t he white iris. Huntington’s known where has disease is at is genetic t he t he risk allele test for condition patients caused high dominant a and until by of do a are is no dominant developing not HD is mild develop positive to longer allele, t he any t hat begin able so disease. to wit h, care anyone Some for who people symptoms so t he concerned person it is not disease. 292 835292 CSEC HSB Unit C.indd 292 08/01/2015 16:17 Heredity Sickle and cell variation Variation anemia Sickle cell blood cells anemia is contain a condition t he production of alleles. allele normal H some stage t hat results oxygen-carr ying haemoglobin is from a pigment gene mutation. haemoglobin. controlled by a gene (H) Red The wit h two N The However at controls in t he production human ancestr y, a of normal gene haemoglobin. mutation led to a new S allele, wit h This to H a . This different small carr y controls amino difference oxygen. haemoglobin (see allele Figure At acid t he at reduces low collapse one t he oxygen into a production point ability of its of haemoglobin t he concentrations, sickle shape can have genotype one H of t hree genotypes: wit h t he haemoglobin. medical t he wit h name molecule abnormal of t he H N H N , H S H S and H S H produce red genotype This treatment, is H people cells wit h normal . red die when blood cells haemoglobin. People t hey wit h This are produce sickle wit h cell t his red blood anemia cells and, condition the sickle low oxygen par ts of sickle cell the parasite the cell world trait gives causing People normal condition with the young. some abnormally some Those wit h haemoglobin. S H called blood are wit h t he wit hout likely to is trait wit h t he haemoglobin known suffer a as t he be ver y genotype H abnormal some cell ability so this advantageous. condition malaria (page to is malaria. 325), nds sur vive It appears it much and H produce trait. to concentrations, resistance they ill S and sickle reduced abnormal constant N of ten disorder N H S Those lengt h. cells hence molecule C.4.10). N t he haemoglobin along N People a transpor t normally. oxygen In fact, This occurs that Plasmodium, more at in because difcult to p infect red blood cells that contain the abnormal Figure who see Chromosome A mutations chromosome ● ● In mutation t he str ucture t he number humans, wit hstand of of such t hem one (or a spontaneous more) chromosomes mutations better and, are in change chromosome(s) in a Blood sickle some become cell from a of anemia. person the red Y ou blood can cells sickle-shaped in: or cell. usually some has that have is C.4.10 haemoglobin. let hal, cases, but plants ourish as a seem result to of be able to t hem. Human cells are sometimes found in which the chromosome number is greater than the expected 46. This occurs from the fusion of a normal sperm or egg cell with an egg or a sperm cell that was produced after a pair of homologous chromosomes failed to separate during meiosis (Figure C.4.1 1). Such a failure is called chromosome non-disjunction. The best known example of chromosome non-disjunction in humans is Down’s syndrome. People with this syndrome have an extra copy of chromosome 21 in each of their cells. Children with this syndrome have a characteristic appearance with a roundish face and almond-shaped eyes. In addition, they suffer Did varying degrees of mental retardation, stunted physical growth, heart you know? ? abnormalities and reduced resistance to certain diseases. Why is genetic variation Gene mutations in inuenza the any population between of individuals. differences. organisms Some However, occur Because important? this In commonly virus. some t hat reproduce of t his is inherited. variation sexually, results This from inherited t here is variation environmental variation virus very will mutates difcult last for to so get years a often, it vaccine against is that ‘u. is 293 835292 CSEC HSB Unit C.indd 293 08/01/2015 16:17 Heredity Variation Normal Non-disjunction impor tant more for t he offspring competition sur vival t han for t he such of t he species. environment resources as Organisms can space, suppor t. water food generally Therefore, or and variation produce t here is mates. Parents The organisms more of t he t his Gametes likely next would Figure C.4.11 t hat best As generation. result in alleles, better to able are sur vive. favourable a If able t heir ot her compete t hey will or escape predation reproduce and be are will t he favourable characteristics in t he next generation inheriting words t he next generation would organisms in to result, be parents inherited, be t hose genetically sur vive. (types) Poorly p to Chromosome t he non- disjunction adapted organisms population. sur vive, but t hey competition. need Organisms For produce not t hat fewer example, an are die for not offspring animal t heir alleles successful t han t hat is in t hose unable to be lost from competition t hat to are nd might successful sufcient in food, key or bacteria not a plant lacks to t he to unable to produce as needed to produce large giving antibiotic resistance Antibiotic resistant for the first resistant and example bacteria As grow reproduce t he use growing and bacteria stop it can ot her plants, is bacteria seen when continues produce antibiotics resistance has resist meant t he sur vive. mutations in pat hogenic (disease-causing) types which are resistant to antibiotics to has increased, t hem. t hat A t his antibiotic. cer tain chance type While of t he bacterial mutation, bacterium is non-resistant cells which at an have has resulted advantage types will die, in because t his There will be less competition, e.g. for food from t he type non- killed resistant all as offspring. reproducing will are of developed variation, antibiotic of time non-resistant or chlorophyll numbers treat microorganisms disease much with mutation Anot her used t hat antibiotic bacteria antibiotic is energy resisant to be bacteria used now type, resistance is so t he shown resistant in Figure type will ourish. This selection of antibiotic C.4.12. resistant Questions to the antibiotic selection has antibiotic resistance occurred 1 What 2 Name 3 a Figure C.4.12 Selection for variation? five causes of genetic variation. for What took p is up would you expect weight-lifting on to a happen regular to a basis? person’s physique b these Would if he/she changes be due antibiotic to resistance the environment 4 Define 5 Explain 6 Which 7 mutation why of or and due to name a variation the is following both? mutagen. features intelligence; As anaemia cell or important. haemophilia; sickle genes is eye a show colour; severe discontinuous variation: albinism; capacity? disease, lung what might you height; expect S to happen over production? 8 In which the course Explain parts of the your of time to the H allele controlling its answer. world is the sickle cell trait advantageous? 294 835292 CSEC HSB Unit C.indd 294 08/01/2015 16:17 Heredity C.5 and variation Monohybrid Monohybrid inheritance Learning By Introduction to the inheritance is t he passing down of a single parent to offspring. Examples of t hese single be of this able topic you to: characteristic ● from outcomes genetics should Monohybrid end inheritance characteristics in define the terms used in human genetics inheritance are blood groups and t he ability to make t he skin pigment ● melanin. The basic “laws” of genetics were rst developed by explain monohybrid Gregor inheritance Mendel, who studied genetics using pea plants. Alt hough he worked wit h ● plants, t he including “laws” t hat he discovered apply equally to explain sex linkage. animals, terms following Knowledge questions genetics humans. Genetic The of of glossar y t he related should terms to in help t his monohybrid Chromosome a thin, Gene a length a single of Allele is so an as DNA protein; the you will structure that it ABO alternative group group B is which carries the blood form has one of a for allele is dominant it will Recessive if an allele is recessive it is describes Heterozygous refers to an an individual’ s individual non-identical of gene, blood the genetic instructions gene always only e.g. information for making e.g. one gene controls hair colour, the group A express expressed in alleles of the a gene and itself when make-up single same controlling another in the the for blood phenotype dominant for to an individual controlled by two one allele characteristic characteristic gene, – is refers genetic whom characteristic the problems. attempt inheritance, (pure-breeding) e.g. you present Genotype Locus genetic another single allele an Homozygous genetic as carries unit group; if two the basic Dominant not you on blood is attempt help inheritance. thread-like controls and you glossar y in e.g. whom identical is controlled by Aa a alleles single of the same gene, AA position on a chromosome where a particular gene is always found Phenotype describes an biochemical Written Answering Using A to physical e.g. blood appearance, group e.g. brown-eyed, or A activity genetics symbol individual’ s make-up, questions represent the allele for normal skin pigment and the answer the p symbol a following to represent short the allele for albinism (see page 292) questions. Figure a pea how 1 What 2 Give is the the alternative genotype allele to C.5.1 flower. His plants Gregor Mendel experimental holding work on enabled him to discover characteristics are inherited A? of a homozygous of a person person with normal skin pigmentation. ✔ 3 Give the genotype who is homozygous recessive albinism. 4 Give the Study Look genotype of a person who is tip with Figure C.1.3 for understanding at these terms help in used in heterozygous. genetics. 295 835292 CSEC HSB Unit C.indd 295 08/01/2015 16:17 Monohybrid Heredity inheritance 5 What (b) would be the phenotype of a person whose genotype and variation was: (a) Aa; aa? 6 Why are 7 Why is e.g. people the AA, What is 9 What are albinism genotype Aa 8 with or humans homozygous? always written as pairs of symbols, aa? meant the of always by the term possible locus? genotypes for people with normal skin pigmentation? It is completely humans t hat we and would from t hem. Mice make share t he mouse, we appear mice are of at t he and about 3:1. is brown C.5.2 and different Variation white alleles mice of the in same fur and There are are mouse many much exper iments is times time genetics. many a to For are one varieties (albino) reason form of mice wit h long anyt hing species domesticated white so lear n different different using is ver y This patter n set of The allele is t he mice. times close of If of t hese and we of mice t he house mice, mice but wit h to breed one many we achieved parents and White colour bred by and brown fur is in t he taking t he grandparents mice colour t he among offspring enough brown mice repetitions can results introduced are t heir investigation inher it ance summarise organisms are does dominant bred not feature offspring as t here t here giving t hemselves are a you are were mixture 35 nd white t hat of brown t here mice: brown hundreds (anot her of mice a ratio to offspring 13 t he 3:1. offspr ing whic h be t heir mice fur t he feature. offspring many can brown. brown humans) t hat t hat white are recessive you as in Wit h in t hat If sure This means phenotype. unet hical 2.7:1. rst This suggests example, making generation colour t hree by homozygous. brown-coloured is can This star t lines. next white For Mendel Figure There breeding generation investigate laborator y are bred t he ratio We to any and patience investigation t he all. t hat which p pure all white t hing conduct common. The an of animals in generation exactly When at to gestation lot experiments from toget her and a musculus. look parental had world. t he fur. Breeding mice genes Mus shall brown need suitable many across unet hical anyway t he t his in can white idea as be deduce of explained t hat fur using is as brown follows. fur Looking colour is at t he dominant. recessive. letters to represent t hese alleles. follows. mice: are expressing gene for ● Mice have a gene t hat controls t he colour of fur. coat ● The allele which causes brown The allele for white fur use t hese symbols fur is represented as B colour ● We ✔ Exam can now you read inheritance, gene fur about decide controls. represented and by follow b a standard way to explain t he tip genetics When is In a pattern what this feature example it of t he cross wit h t he mice. of Parental phenotype Parental genotype Brown x White BB x bb the is colour . 296 835292 CSEC HSB Unit C.indd 296 08/01/2015 16:17 Heredity Each and adult variation mouse is Monohybrid diploid and t herefore must have two symbols. Parental male phenotypes Now we can Note t hat: continue t he diagram as shown in Figure brown × female fur white fur C.5.3 Parental ● inheritance BB × bb B + b genotypes We have represented We have used t he types of gamete not t he number of gametes. Parental gametes ● t hat you are a met hod strongly for laying advised to out t his cross (shown here in italics) use. F genotype Bb 1 ● To represent t he F offspring, we have used a device called a Punnett F 2 phenotype all brown fur 1 square. F phenotype brown fur × brown × Bb fur 1 As can be seen in Figure C.5.3, we have a 3:1 ratio, which is what Mendel found. How F genotypes Bb 1 can you tell the difference between an animal that is homozygous F + gametes 1 dominant and one that is heterozygous since they have the same male phenotype? with This unknown is possible genotype with and an a testcross animal that that is involves crossing homozygous the gametes animal recessive. We do B know that the animal with the unknown genotype must Parental be BB or male female female × phenotypes short b Bb. hair long hair gametes Parental SS ss genotypes genotypes F BB 2Bb bb 2 Parental and S phenotypes s + brown gametes F phenotypic 3 fur brown brown fur : fur white white fur fur 2 F genotype Ss 1 ratio F phenotype all short hair 1 p Parental male F brown C.5.3 explain × phenotypes Figure A genetic diagram to female fur white fur phenotype short hair × short the inheritance of fur colour in hair 1 mice Parental Bb bb F genotypes Ss × Ss 1 genotypes F + gametes ✔ 1 Study tip Parental b + gametes male gametes T o become you male gametes need with practise genetics answering s S problems. B familiar to book b look but at There to one give are several more involving help, in this we will cats. female female b gametes gametes Offspring Bb genotypes brown bb fur white ✔ fur F genotypes SS 2Ss Study tip ss 2 and phenotypes and phenotypes short Offspring 1 brown fur : 1 white hair short hair long hair fur phenotypic in F phenotypic 3 short hair : 1 long closely Figure offspring the genetic What diagram would be like if the male the with ratio brown p at C.5.4. hair 2 ratio Look Figure C.5.4 genotype of A a testcross brown to mouse find the p Figure length C.5.5 in The inheritance of hair hair dominant, was homozygous BB? cats An example of a human condition controlled by a recessive allele is albinism. Before you read further, look at your answers to the questions for the written activity above. 297 835292 CSEC HSB Unit C.indd 297 08/01/2015 16:17 Monohybrid Heredity inheritance ● Parental male phenotypes Two female normal × people normal skin colour may have a child wit h variation albinism. normal ● pigmentation Assume pigmentation A pigment Parental wit h and Aa is t he and a allele is t he t hat controls allele t hat t he gives formation rise to no of normal skin pigment. Aa genotypes ● As bot h t heir produce skin pigment t hey must bot h have, at least, one A in genotypes. Parental + gametes ● male To genotypes, gametes A produce Ot her a is an in examples governed condition by a albino ot her of child words bot h bot h monohybrid recessive governed by a allele must are have, dominant least, heterozygous inheritance and at (see include Huntington’s one a in Figure cystic disease t heir C.5.6). brosis which is which a allele. female gametes Codominance and In examples, t he previous recessive. Offspring genotypes AA 2Aa t his alleles we need stated not t hat be t he an allele case; is eit her sometimes dominant bot h are or expressed aa when and normal However multiple pigmentation t hey occur toget her in someone wit h a heterozygous genotype. In albino phenotypes t his Offspring 3 normal pigmentation : ratio Figure C.5.6 albinism. An The inheritance example of t he alleles are said to be codominant. albino phenotypic p case We have also t he case; sometimes a of single inheritance of demonstrates t he t hat t here characteristic. inheritance monohybrid assumed gene are These gene bot h a for t hese only more are t he ever t han referred ABO has two to blood two alleles as alleles. of a multiple groups is a This gene also not controlling alleles. good is The example t hat concepts. On the surface membrane of our red blood cells are proteins called antigens: A ● Parental male antigen A – controlled by allele I antigen B – controlled by allele I female × phenotypes blood group A blood group B B ● A Parental I O B I I O O I ● neit her antigen A nor antigen B – controlled by allele I genotypes A Alleles B I and A I are codominant (t his may also be represented as I B I ); Parental A O I B + I O I I O bot h gametes male A of t hese alleles in Table C.5.1. A I can over t he occur, recessive giving t he allele I . All genotypes possible and combinations B I Note t he new way of representing phenotypes alleles: t his shown notation is O I always To B dominant gametes I I are B I used become wit h multiple familiar wit h alleles. t his notation, suppose a woman is heterozygous O I for group B and her husband is heterozygous for group A. We can represent female t he inheritance of ABO blood groups among t heir children using t he gametes O A I I O I O I diagram O in Figure C.5.7 . I Transfusions A Offspring I O A I I B B I I O I O I O I genotypes The Offspring blood phenotypes blood blood occasion group group group group A AB B O is during If someone rejected. p Figure blood C.5.7 Inheritance of blood t he ABO It transfusions blood receives will clot blood and of may – a see group t he system Case different cause Study becomes blood deat h. on group Blood is page impor tant to us 129 t hen it matched may be before a ABO transfusion groups when blood about 20 Rhesus R and and people different blood usually blood group group system receive blood systems. which is The of t he ot her controlled by same one a group. t hat gene you wit h There know two are is t he alleles, r 298 835292 CSEC HSB Unit C.indd 298 08/01/2015 16:17 Heredity q and T able Blood variation C.5.1 group Monohybrid Phenotypes name and genotypes (Phenotype) of blood groups ✔ Genotype A Group A I Group B I A A I or I or I Study B I B I A AB I Group O I have A O positive RR Rhesus negative rr Try these squares 1 A couple their and first 3 blood group has A had cat O? a knows make breeder testcross? baby. to ● genetics bags of has Use of ● opaque ● labelling of genetic She blood identify a a one and copy offspring two copies of the gene as in O I Rr genetic in this and A, diagrams with Punnett Chapter. O. What blood diagram and group why men How the the – it blood who short-haired is group (with the B, probability blood Punnett that group square) AB to the to the is Desmond, both group group B. have Can testing be the but blood he can father. be he of group the only father? be used Suggest a in test father. which could diagram is cannot of cat father baby could cat explain be homozygous breeder your find out by using a answer. Activity gummy bears genetics bags, certain identification genetic the is Marcia heterozygous. gummy offspring a AB group Explain positive Practical The use groups her. his answer. testing or and examples blood Use knowing your dominant have parents answer. Desmond can I, 1 Always the be: even that in the denies paternity see will your Explain problems. can have Marcia A. problems child blood explain 2 you gametes gene activity genetics genetic as I I Rhesus Answering the B I O Written that O I of Group tip O Note B inheritance e.g. bear (also known as jelly babies) to represent the crosses paper bags – not clear plastic bags pens Requirements Many gummy bears represent white) Y ou to 1 need Look 2 work through different Choose in different colours – red, yellow, orange, colourless (to green a this genetic a of and group for chapter ratios particular this on that monohybrid you genetics activity. have cross: genetics come here and identify the across. are some to start p ● T wo alleles: (colourless one dominant gummy (red gummy bear) and the other Figure C.5.8 Genetic gummy bears recessive bear) ● Cross 1 homozygous ● Cross 2 heterozygous dominant x x homozygous recessive heterozygous 299 835292 CSEC HSB Unit C.indd 299 08/01/2015 16:17 Monohybrid Heredity inheritance 3 Decide 4 the divide the to ratio, the Write suggest Make from full Sex offspring else. full so that is genes “parents” ratio. be The have number produced needs to and be close exact. identify gummy it as yours bears and and swap with work out the ratio features you have and involved. are follow learn your the to to the diagrams you t he t hat to show how inherited the how are on t he characteristics blindness us and is the through examples to X can vision are it is or are format Y a a in two this genetic and a case The dominant likely controlled (a to by to generations. chapter. chosen T o Write make several a of diagrams. N/n. how The t he X for sex of colour to colour for not t he of colour clot). gene has t he Genes Examples normal t he between as C.1.7). red-green fails wit h alleles C are blood distinguish t he sex-linked. people The (Figure genes which symbol to be chromosomes. on chromosome genes to two child. sex on few said in t he carried sex-linked disorder handwriting on are be are are sex ver y by show t hat wit h carries colour-blind represented in do chromosome are diagram difcult lower and alleles to most haemophilia produce of not hing smaller t hat constr uct vision inheritance have These chromosome since bag out bears to have cross diagram chromosomes. Let the of gummy genetic linkage t hat on not Count genetic offspring according does type of variation linkage Some Y but the the these Sex number something someone 5 total and colour been upper used case C c allele for normal colour vision is written toget her wit h t he N X chromosome as X . The recessive allele for colour blindness is written as n X . Including t he X chromosome N Parents mother × ● father The woman colour N Genotypes X n is X shows t his n X condition is sex-linked. N and t he man is X Y as t hey bot h have normal vision. N X X Y N ● N Gametes t hat n X We know We can X is X n X as she has a colour-blind child. Y ● female gametes In Figure blind N C.5.9 child do t he there being cross is born a 1 to as in 4 this shown (i.e. in 25% couple. Figure or C.5.9. 0.25) Any boy chance has a 1 of in 2 a colour- chance (i.e. X 50% or Since N X now n X N woman N X X t he N N X X 0.5). t he woman has t he allele for colour blindness but does not n X express it, she is described as a carrier male gametes The N genetics of haemophilia are exactly the same as in the previous n Y example; the N Offspring genotypes X X gene is is carried recessive. on the Imagine X that chromosome a couple who and the both allele have for blood N X N and the disease - female with colour vision - female with colour vision with n X normal clotting time have a haemophiliac son. If we use the H phenotypes symbol N X Y - male with colour vision Y - male with colour blindness X to represent an X chromosome blood the Genotypic ratio clotting female male has being allele for normal recessive and allele the for symbol X to haemophilia, represent we can an X chromosome constr uct a diagram with to 1:1:1:1 explain No the h n X with colour colour vision, there is a 50% chance blind of what has happened to this couple. any ● The woman is XX and t he man is XY. H p Figure C.5.9 Sex linkage and colour ● Both have blood that clots normally, so the man is X Y. blindness 300 835292 CSEC HSB Unit C.indd 300 08/01/2015 16:17 Heredity ● and They variation have a Monohybrid haemophiliac child, so t he woman must Parental H carr y ● We a recessive can now do allele. t he She cross is, as t herefore, shown in X Figure wit h red-green colour-blindness, t here is a C.5.10. 1 H in 4 genotypes X t his chance couple. t hat This counselling is a is haemophiliac taken into child account will be when male h H X X born H h X H X , X Y , to genetic given. female Genetic Y (i.e. Gametes 25%) Normal × female Parental As Carrier phenotypes h X inheritance counselling gametes H h X X Suppose a couple have had a child with haemophilia or sickle cell anaemia and they want to know the H H X X H H X X h X chances of another child of theirs having this condition. male gametes The couple can go to a genetic counsellor. Genetic h H counsellors need to have a good understanding of Y X X Y Y human genetics to be able to explain things clearly and to help people make up their own minds. A woman may H X H H X X H Y X h h X X Y go to a genetic counsellor having had the results of a test such as amniocentesis (see page 260 Offspring and Figure C.1.1). phenotypes Female : Male : Female : Male with with with who normal normal normal has clotting clotting clotting haemophilia time time She might know that if her child is born it will have Down’s syndrome. The genetic counsellor will explore time but all the medical and legal options with her, which may h has include termination of the pregnancy (abortion). Genotypic Males are much characteristics recessive it will other X than harmful usually X be are allele he will Answering controlled Explain how the a one by a if If of a harmful female her X dominant he that the : 1 : 1 : 1 has the p Figure C.5.10 Sex linkage and haemophilia chromosomes, allele male inherits 1 ratio sex-linked on only the her has one harmful condition. activity colour by show However from genetics Red-green on therefore suffer to females. masked Written 1 likely chromosome. chromosome allele, more X (carrier) problems blindness allele normal 2 is a recessive, sex-linked condition. It is n male and normal female could have a colour-blind child. What 2 A couple from to sex a know child that family, disease. children there 3 the haemophilia. start the will was People a with Suggest future will Use of was visit a genetic the only case of are happen genetic in now to to he cousins died. counsellor to show would the to the the The explain of couple genetic young are about that any counsellor about of their say if family? cases your very information chances successfully number died seek husband’s treated the diagrams distant when What haemophilia haemophilia use six diagram haemophilia. might wife’s genetic have what and a one He but be? with of a blood protein. haemophilia in the answer. 301 835292 CSEC HSB Unit C.indd 301 08/01/2015 16:17 Genetic Heredity engineering and variation Questions 1 Explain the term monohybrid 2 Explain the terms gene, inheritance allele, genotype, homozygous and heterozygous 3 The Rhesus The dominant controls Explain who is Define 5 Explain 6 Why the is a a Write a is people sex fact is controlled Rhesus by positive a gene blood; with the two allele alleles. r blood. with Rhesus determination red-green colour-blind female? system controls positive blood may have a child negative. terms how R negative two blind it 8 Rhesus how group allele Rhesus 4 7 blood sheet on and colour-blind male more linkage female likely haemophilia: sex to what be it could arise. produced is, how it is than a colour- inherited and how treated. Describe the differences between the chromosomes in males and females. Learning By the should end be C.6 outcomes of this able topic you to: DNA describe the is t he knowledge tests ● Genetic for engineering genetic material of to DNA genetic of all develop conditions, organisms. ways treat to and We have genetically cure exploited modify genetic our species, disorders, develop analyse structure evidence in forensics and compare t he genes of different species to examine of DNA ● ● explain what involves discuss advantages disadvantages engineering. relationships But what between t hem. genetic engineering the t he of and genetic is molecule into DNA? wit h a Figures str ucture chromosomes during ot her enzymes proteins can for like during times in reach it t he C.6.1 and a C.6.2 spiral nuclear t he life of and use t he a show staircase. division cell it is t hat It is a ver y packaged ver y (mitosis not DNA and packaged information stored in is meiosis). so tightly t he genes long tightly However, and to make cell. Strand of core p Figure The C.6.1 DNA is The the DNA genetic in each of protein chromosome material; the DNA histones is packed provide around histone structural molecules. support 302 835292 CSEC HSB Unit C.indd 302 08/01/2015 16:17 Heredity and Genetic Genetic variation Genetic engineering engineering characteristics of an is t he (recombinant process organism by involved inser ting in DNA technology) changing genes from one or anot her more organism the is into its t he DNA. same The “foreign” species, a DNA totally could different come from anot her or DNA species be DNA made individual up of engineering t hat has of two strands been forming synt hesised in t he laborator y. DNA can even be moved from a human into a a bacterium. Do not t hink t hat t his a of is t hat unusual: vir uses do t his all t he the strands are held double helix together time. Scientists t hink t hat lot t he DNA we have in our by chromosomes weak bonds has come from For many years, t hrough like However, possible is as our developed, knowledge a gene and has “factories” DNA your of from t he genotypes plants. t he Later, programme of cer tain selective t hat was organisms breeding used to produce cattle. genetics one DNA t hat and e.g. allowed Practical changed Hope recombinant engineering, into have animals Jamaican take as specic were t he to known cells humans rearing programmes breeds vir uses. has organism increased, and technology us to produce turn or, it transfer more has it products anot her. commonly, microorganisms useful become to for and This genetic p Figure C.6.2 The double helix of DNA mammalian us. Activity onions Requirements ● a kitchen ● ice bath blender to keep materials cool as ● detergent, ● ice necessary ● some ● sodium ● a ● pineapple not Y ou juice 2 use or juice wear cause Chill the so on Make a thick from ice fresh or not by so “soup” by test ● glass in the a juice doing this out wash placing throughout beaker ● your as for a source a at naked if of protease; you least activity: ames. spill 2 hours, 3 water , water and Strain the e.g. a use pinch mixture 100 of table and is on or them. overnight. procedure. blending cm ethanol Pineapple any your onions with a little salt 3 cold do carton) practical any hands freezer (industrial alcohol) rod from this near liquid tubes pineapples while carry irritation ● pineapple protection do ethanol it cheesecloth (made skin Keep / salt) pineapple eye ammable can (table muslin tinned should highly 1 chloride washing-up ethanol denatured onions strainer cold e.g. and some 3 of salt. collect chopped onions, Blend high the on liquid part with speed in a 200 for cm 15 of cold seconds. beaker. 3 4 Add 5 Let 6 Pour the each about 7 30 the Add a cm of washing-up mixture settle mixture few one into third drops of for 5 test liquid to10 tubes and swirl to mix. minutes. or other small glass containers, to make full. fresh pineapple juice to the containers. 303 835292 CSEC HSB Unit C.indd 303 08/01/2015 16:17 Genetic Heredity engineering 8 Tilt the test ethanol the is soluble Use the 10 (IDA) mixture. form 9 a is pulls more a the small you C.6.2 making use than Gene a of can vectors produced called model materials transfer gene a the of 1 Cell use of broken open enzymes. strands DNA can cut into by restriction These a nd be done by small joining genetic 2: This Stage 3: The forget all it want placing to are sorts easily take lots of and simply and Stage on into ethanol and will meet. tube and onto the end of the touch rod. strand, it precipitate. measure in of DNA the one to top top. “spool” will it in on on the ethanol in mass any of suitable a photograph. of instructions materials. make a Find model. available some Try to online instructions make a better up is DNA DNA. from from inser ted a gene “carries” of two Organisms DNA or it into a cell. Alternatively, into a cell. Examples known more as plasmids. different containing DNA organisms recombinant is DNA are (GMOs). engineering is ring t hat loops organisms isolated gene vector illustrated a here involves t hree stages. donor. into a carrier (vector). by gene wit hin its vector is transferred to t he host. DNA are of the gene shorter the use cell wit h t he desired gene is broken up using enzymes. DNA (genetic of enzyme material) using on can vir uses gene pull where you by There from are A The 3 DNA. a 1: you stick should layer float layers well-chilled released fragments a of into Stage Isolation 2 don’t placed of if DNA the a will dissolve ethanol DNA layer forms and the lid. DNA you recombinant type a As not it of diagram. genetically-modied The Dip the towel the be by DNA. ethanol paper with and and that water does volume DNA models in a save so than DNA molecule. the tube same water the rod the variation yourself own is the successful this Figure one on simply been your that or the collect into the dense salted where stringy DNA about into less but to sample Make for long, is T wirl container have Tr y rod Pour slowly water, layer. DNA Dry very 45°. clumps glass white to Ethanol in white product, If tube and is then extracted from the restriction enzymes. These cell. cut The the DNA DNA at is cut precise into shor ter places that lengths scientists separated plate can identify. The gene As a result, one long strand of DNA will be cut in several places. fragments probe is a required may be By the active use probe of a the want can the be piece enabling us be found binds of to to DNA from par t of (Figure t hese t he C.6.3). nd our gene acquire t he genes pieces. desired from The To gene. probe among t he do t his, This is a gene probe slightly ot her fragments. radio- fragment There containing now which single-stranded radioactive, 4 must used gene are ot her ways to required. The genetic engineers you identified who modied bacteria to produce insulin realised t hat t he cells t hat make probe insulin t heir make p Figure C.6.3 Stages in isolating a in t he islets cytoplasm. copies of of So viral Langerhans t hey RNA used in in newly t he t he pancreas discovered form of DNA. must have enzymes Before a from 1970 lot of RNA vir uses no-one in t hat t hought gene t his was possible. 304 835292 CSEC HSB Unit C.indd 304 08/01/2015 16:17 Heredity and Anot her variation way is Genetic simply to make t he DNA required in a laborator y. 1 engineering Insert the gene These synt hetic genes have exactly t he same proper ties t he DNA of as DNA gene from viral organisms ot her and can organisms Insertion of be for the inser ted t he into production isolated gene bacteria, of useful products. a vector (carrier) into yeasts DNA and 2 virus Place DNA A vector is a plasmid or vir us which can carr y a gene from into donor the in the to virus recipient circular The strands rest One (host). of this enzyme, anot her Several of DNA will restriction enzyme, DNA are (plasmids) account a vectors known, that are concentrate enzyme, ligase, is is used e.g. found on used to certain the to join in use cut some of t he t he vir uses and bacteria. vir uses. viral desired DNA gene and to bacterial bacterial t he DNA of Generally, Vir uses t he vir uses t hat injecting isolated vir us. t hat infect t heir gene The attack bacteria DNA into isolated into eit her attach t he anot her gene cell. is placed bacteria to t he This or inside yeast outside provides of a t he cells t heir way of are 3 DNA vir us. host used. hosts Virus to the attaches host DNA 4 DNA and getting t he cell. Viral inserted Transfer to a new Host cells are now attaches to wit h required t he some infected of t he wit h host gene) t he cells into modied and injects vir us. its The own vir us host DNA. host produces The host cell DNA (along will now ● In a be and used which extracted manufacture t he desired Figure C.6.4 Transfer of a gene into a product using a virus as a vector C.6.5). fermenter, large can t hem. bacterium (Figure The required chemical p ● now into host the ● and injects amounts t he of bacteria t he or yeasts divide repeatedly and produce Human Insulin Production product. DNA ● The product is har vested and used. human pancreas cell Proteins are made up of amino acids linked together in a certain order. bacterial DNA The sequence of bases in DNA is a code that determines the sequence of human insulin plasmid producing amino acids in proteins. Two processes occur inside cells to link amino gene DNA bacterium acids together. introduction ● Transcription – a copy of a gene is made as a small, recombinant plasmid molecule called ribonucleic acid (RNA). The of shor t-lived molecules of RNA DNA DNA into DNA are out recombinant a bacterial cell with restriction small enough to pass into t he cytoplasm carr ying t he “message” enzymes for making a par ticular protein to ribosomes (see Unit A.1.2). recombinant bacterium ● Translation code in – ribosomes link t he amino acids toget her using t he RNA. recombinant bacteria human and insulin Insulin multiplying producing human insulin fermentation All diabetics used to be treated wit h insulin obtained from pigs extraction tank & purification and cattle, which were slaughtered for t he meat trade. People and In t hat also t he diabetics t hat 1970s, humans. t he were demand scientists They were at for r isk identied able to of getting insulin t he transfer would gene t he diseases be t hat piece more from animals t han t he codes of DNA for wit h into bacter ia. recombinant Figure DNA C.6.5 divide to shows how produce t his many is t hat codes done. in for to GM make bacter ia human available in are given insulin. t he Human nutr ients insulin and more bacter ia. conditions produced like insulin Bacter ia p These insulin supply. insulin human insulin of were human worr ied in tank t hey t his need became Figure in the C.6.5 1970s bacteria that This to process make could was carried out genetically-modified produce human insulin 1982. 305 835292 CSEC HSB Unit C.indd 305 08/01/2015 16:17 Genetic Heredity engineering Other ot her medicines made using genetically ver y good cells are at Examples protein modied and of B.6.4), (see B.7 .1) human blood hormone is The controlling manufactures treatment t he of case Genetic Many put growing, and study are and year. but or people t hat rice for t hat goats, rice traditional from one larger a The plasma of cer tain hormone protection to treat not are always mammalian of (see B.6.4), clots from cer vical haemophiliacs gland was and t he affects regulates rst Escher ichia t hat crops cotton, to to coli be (E. cancer (see ten our made coli) hormone about beta not an can C.5) is growt h by a which used people in “gene t hen t he per million also However, yet be par t such for it breeding, not example, its in a is tiny GM milk quantities goat in a can year for a go on t he crop from of genetic A. This blind each large scale, a healt h is no to of poor can be and cattle, engineering faster ot her be sheep sh GM possible by can of rear. much is e.g. type are produce as genes vitamin modied, it t he rainfall diet. and possible been is result genetic selective For in t hat t he who farmers which available protein is putting make t here of have eat little growing t heir (2014) available modication as for milk disadvantages anot her, to crop t hey is are benets of t heir yet as children genetically in as t here t hat are t he when such used of approved been while where is should proteins features carotene, number been of killed qualities, beta livestock tobacco used are carotene t here pigs be and grow impor tant have or Examples pests will t he and maize make are to t han move met hods, produced t he using same collected in genes and much quantity from of 90 000 donations. disadvantages weeds GM which quantities. human blood to diseases are production blood manufactured insect rice genetic met hods, species chemicals The crops human and of for bacterium reduce is chickens advantages growth forming pituitar y nutritional quickly. Advantages The so have animals ver y so happens produce and industrial production modied. body, help t his and weedkillers into plants from stature soya, so t he to whom grows sheep, In when Domesticated goats as improved done The if genetically bacteria yeasts human bacteria B.6.4). resistance, modcations. been t he shor t resistance, Additionally, has in resistance, pest drought maize in of such human protein t he its hormone. type crops, herbicide placed by modication crops into secreted t he a so for into However, hormone rate. is are inuenza a This It ways thrombin 8, growth machine”. research substances. for factor for bacteria. proteins, similar medicines vaccines gene chemicals modied in prevents and Human ot her these that (see and producing also medicines (see variation medicines Many a and so t hat microbes dangerous, t hey are could and herbicide become escape consumers resistance “super weeds” from could t hat laboratories become resistant pass from farmers and to factories, GM crops cannot foods to control, and become because of 306 835292 CSEC HSB Unit C.indd 306 08/01/2015 16:17 Heredity t he fear and of variation t he advantages t he discriminates Moral, new to against ethical people in production organism gene(s) T oxin and are t hat by t he small and of making t hat GM develop farmers who technology also gives and GM crops. about transgenic DNA t he use of organisms. from a market cannot environmental concerned contains (poison) unknown. companies Many t he Genetic afford This concerns transgenic different huge it. recombinant A engineering species DNA technology organism and is expresses an t he proteins. production in plants A bacterium Bacillus thuringiensis produces a toxin that kills the larvae of moths and butteries. The bacterial gene controlling toxin production has been isolated, inserted into a vector, and transferred into the cells of tobacco, tomato and cotton plants. These modied plants now produce the toxin so giving them protection against damage by moth larvae. The toxin is harmless to humans but any pests that have a resistance to the toxin will survive, reproduce and increase in number making the protection useless. Resistance of this type has already emerged in the USA where GM crops are widely grown. Herbicide resistance Soya has This herbicide been is soya plants light, weedkiller different in t he soil develop weeds for Pollen or where t hey become control. of lead anyt hing an have to are be and Muslims, Bot h given of new organisms GM e.g. crops to crop. and use The are t hat could crop could t hey might development more be of money had a might gene (herbicide). compete yields. The different herbicide concer ned t his will wit h use breaks t hat make of t he herbicides down weeds t he will control of “escape” dispersed possess a outside gene “super weeds” on weed for a t hat control t he areas herbicide farmers t han on t he and cannot control transgenic made not transgenic and upset to in evolution into speed t hem up t hat t he allows t hem evolutionar y to process of genetically products bacteria used which t he organisms transplant use vir uses pat hogens could might up insects. humans could speed inser ted This specic to bacteria become a t he being can Mutation t he t hat reducing having People weedkiller (GM) spend insecticide-resistant Attempts of weedkiller difcult. insecticide. Objections growt h products. t he organisms crops produce nutr ients, a weeds else. Transgenic Some to kill saves grown, Farmers tolerate to and to from are to crop and modied seeds t he water dur ing more modied on yields har mless resistance Genetically so sprayed times into much soya genetically increases at in in or engineer containing might “balance so Some genes t hat t heir people, from organs e.g. Jews pigs. viruses genetic we pigs operations. of engineering not be nature”; able e.g. could to mutate control. transgenic and Transgenic salmon grow 307 835292 CSEC HSB Unit C.indd 307 08/01/2015 16:17 Genetic Heredity engineering ver y rapidly could same and reduce Genetic have escape show genes have for of all of from ot her t he sh at which been for or genetic This sh farms species to as where t hey t hey are compete reared for t he some lead pay to, for a to you e.g. the a reality. make are years, your soon insurance or care who polygenic Soon own susceptible but health disorders developing screening becoming disorders inherited of is by analysed for could refusing risk DNA genome available cer tain high individuals using whole them. premiums alleles against screening your could are t hey numbers variation food. Discrimination to if t he and they it will to. have people a like for specic have that hear t This available putting who prole condition be possible prole. Tests will companies of be genetic up the shows they disease. Eugenics DNA technology have been disease and an further and used desirable. meaning can be successfully This of inability to to give might the used term to treated insert by make used to into therapy antibodies. humans be genes gene the some conditions However, characteristics “improve” humans; for that this are human people such could as be which eye taken considered race, an to is be the eugenics Questions 1 Outline the produce a processes human involved in genetically modifying bacteria to protein. 2 State three benefits that 3 State three concerns genetic that some technology people has have had about on the society. use of this technology. Summary ● Chromosomes genes. Before temporarily ● ● ● Genes are are a made parts In a diploid cell, In a haploid cell long cell up of thin divides a of structures, it two copies chromosome one of from DNA, chromosomes that so carry that each is chromatids. chromosomes only made its are each that control found pair of in individual homologous homologous characteristics. pairs. chromosomes is found. ● Before gains ● a the Mitosis that cell are is a type nuclear nucleus and it During separate reached the must needs division identical. break have its information of genetically chromatids into divide, genetic chromosome ● can to poles, to divide grow which and each the opposite daughter two daughter chromatids poles reform cell survive. produces mitosis nuclei so of cells each of the cell. When and the cell divides the two. Meiosis during halves meiosis contributes to the chromosome there is variation some in the number from reorganisation next of diploid the to haploid; chromosomes which generation. 308 835292 CSEC HSB Unit C.indd 308 08/01/2015 16:17 Heredity ● and variation Meiosis has two chromosomes As a result animals, ● of divisions: separate; meiosis including Monohybrid An Genetic allele is four the the first is the the alternative division second nuclei humans, inheritance the in in are formed products of inheritance form of a the division gene homologous the chromatids which are meiosis of at a separate. haploid. become single the engineering In gametes. characteristic, same locus on a chromosome. ● ● Multiple e.g. the The locus always ● alleles The three is are when alleles the of place more the on than ABO a two blood alleles group chromosome exist in the population, gene. where a particular gene is found. genotype describes the alleles of a gene that are present in an It result organism. ● The phenotype activity ● ● ● of the Homozygous sex The are sex XY . is have ● Sex the an In protein is ● 8) they using Variation can Variation is Natural a be selection the of a be as X is or Although to the only by on a a or raw on blood from mutations are half the of material e.g. blood are allele and the X standard random for at of another a the inherited XX and his males sperm a usually clotting greater these risk genes. recessive of This alleles chromosome. format fusion of that gametes. (environmental). natural selection to act variation. human height, or groups. different of – chromosome, and over of chromosomes change are sex. non-inherited crossing of sex Males on using show Autosomes gene. Females faulty allele the chromosome. vision continuous, number Y of gene. a father chromosome (genetic) assortment structure X Y . the chromosome. dominant human a a the chromosomes. and by gene caused a of determining colour square acts involve a of alleles X represented either results are is influences. sex have of for one it genetically can mutation). is e.g. random in by important variation or have inherited meiosis; Mutations the Punnett Genetic half genes can variation fertilisation ● only of genes determined and on pair humans is diseases “masked” discontinuous, ● are crosses includes Inherited in a occurrence the genetic be Genetics on. ● the (factor because cannot ● not appearance. alleles different by do offspring is identical have carry humans, linked have that chromosome linkage X. sex X of organism’s environmental determined chromosomes Sex an of genotypes chromosomes ● and genotypes Heterozygous Genetic describes genes gametes; in the chromosomes during and structure chromosomes occur naturally, during meiosis; random mutations. of in a a gene cell their (gene mutation) (chromosomal rate is increased by mutagens. ● The three are: isolation a ● vector; of of human in recombinant the transfer Examples e.g. stages gene of the genetic insulin, from gene a DNA into engineering growth technology donor; a (genetic of the engineering) isolated gene into host. are hormone insertion the and production factor 8 for of useful chemicals, haemophiliacs. 309 835292 CSEC HSB Unit C.indd 309 08/01/2015 16:17 Practice Heredity Questions 8 Practice Section 1 Which of the following pairs of and conditions are variation sex-linked? Questions A Albinism B Sickle C Haemophilia D Red-green and cell sickle anaemia cell anaemia. and haemophilia. A Chromosomes are A mitochondria B ribosomes found in which cell str ucture? 9 Genetic and colour variation red-green blindness cannot colour and result blindness. albinism. from which of t he following? 2 C cell D nucleus A membrane diploid A n B n C 2n cell can be represented by A Assor tment B Crossing over C Random fer tilisation D Shuffling of of chromosomes in in meiosis. chromosomes. of gametes. chromosomes in mitosis. 2 10 Gender Which is determined of t he by statements t he sex below chromosomes, is not X and Y. correct? 2 D 3 2n Which of t hese processes occurs in mitosis? A Males B The are XY gender and of chromosome I Crossing II Chromosomes III of become A II B I and IV C I and II and cell C All D The eggs III and X Section The have t he a A for chromosome only has genes for determining obser ved chromosomes a slide were under stained a microscope and to easy where see. a characteristic written as Aa can What are If tissues chromosomes? [2] be t he had been cheek cells from a as A homozygous B heterozygous C homozygous D none of t he dominant been iii) t he t he formed. above iv) following how sentences correctly describes many present? Name recessive Identify not of a features student ii) Which X chromosome human, 5 by cells IV genotype described sperm B i) 4 by divisions t he III carried XX determined spindle 1 D are is shorter female T wo females embr yo over Formation IV an chromosomes would have [1] process by which cheek cells are [1] one formed type by of t he cell in process t he body named t hat in a) is iii) an above. [1] allele? b A An allele is a lengt h of DNA in a Kuntie An allele is an alternative form of a single identical An allele describes t he physical sets are of siblings. They chromosomes believe in t heir t hey cells even gene. t hough C Krishna chromosome. have B and appearance of t hey are not twins, each ot her. since t hey share a close an resemblance to individual. i) D An allele is t he genetic makeup for a Explain how Use a diagram formed. of discontinuous variation An example A height B skin C gender in D body effects 2 Students colour ways. mass Recombinant DNA technology involves t hree in a Some I A gene within A gene is inserted its vector into III A gene is isolated from is a transferred carrier to incorrect. show genes and on t hese some the differ from variations by is t he correct order t he Complete a I , B I, C II, II, III, host differences in in by many differences environmental t he following tick in t he and t heir table about correct cause of inherited variation by placing column. only of variation Genes and environment stages? (body mass) III Eye colour Hair colour II III, III, ot her caused Characteristic I ABO D are (vector) Weight A twins stages: donor of [5] identical genes. Genes Which each are Cause a how [5] school of characteristics II to is a 7 is characteristic. ii) 6 t his II, blood group I Thickness of calf muscle [5] 310 835292 CSEC HSB Unit C.indd 310 08/01/2015 16:17 Heredity and b variation i) Explain Practice if between it is two environment ii) Explain and t he possible people for t he variation be due to to only. 5 a t he difference sur vey to [4] discontinuous A 3 Sickle between variation examples. [4] Suggest one impor tance species. [2] cell anaemia is caused by a a information help continuous wit h t he use of variation change in among t he town t he t he is was shown blood conducted distribution bank in to t he be controls haemoglobin Group t he unaffected allele of table local in hospital groups. below prepared Frequency A 27 B 20 and times This would of (%) 4 production. O is a gene N H for blood a AB which of emergencies. of Blood iii) in determine Questions t he haemoglobin 49 gene. S H is If t he t he changed allele of t he haemoglobin gene. i) S genotype is H Plot a bar t he person has sickle If t he genotype is H about H t he person If t he genotype Which blood group as? Identify one is H H , advantage what is t he Draw a genetic of having and A State new t he a of woman genetic diagram to show children wit h by a normal cross in a ii), homozygous dominant ii) homozygous recessive heterozygous Explain why woman in children ii) man wit h H a Suggest it wit h a haemoglobin. cell anaemia. has what baby ’s and is baby Mrs. t heir propor tion whilst blood [4] had her name blood group is tag Smit h (Group AB. removed Mr. A) Smit h claim Mr. Hunt (Group B) t hat and she Mrs. (Group O) argue t hat she is t heirs. of t he information is Red-green impossible sickle cross cell least for to t he anaemia. of one man produce i) wit h ii) t hat b sickle [2] t he following about genetic meanings. is about t he four blindness is is a people answer. recessive, t he by your solve allele t he [5] sex-linked r terms genetic normal [2] cross male condition. t he diagram and a to show t he heterozygous offspring female for [6] genetic cross above: terms State t he ratio of normal children to [4] term Meaning A by meant sex-linked of From explain recessive a a fully governed what Use t his table It Explain [2] genotypes child a and any and colour condition. genetic at problem colour-blind Genetic wit h B. [6] 6 combination produce t heir baby O) i) and group S [3] t he will Complete blood H c 4 genotypes and is: i) i) A The (Group t his c people t he t he Using offspring born lost. Hunt t he iii) of of [1] t his N production t he [5] most [1] and From in condition b condition. b found [1] group iii) is S ii) known ii) information groups. has population? i) t he blood haemoglobin. N a show t he N ii) normal to cell collected N anaemia. graph S H length genetic of DNA code for which a ii) carries single State the protein. d Allele Explain an individual’ s for a particular percentage [2] of male colour-blind. red-green among men colour t han children who [2] blindness women. is more [3] genetic 7 make-up be why frequent Describes t he could children. a Two types of cell division are mitosis and meiosis. characteristic. Identify t hree differences between t he two types of Phenotype cell b A man is tongue a tongue roller. non-tongue having Use c a a can be i) ii) is a diagram is by Explain are a t he show sum over disadvantage variations can number chromosomes of State of working. ii) [6] List meiosis of leads mutations vir uses. occur c Dave is a two rice to i) t hat [3] ii) that phenotypic can t he Identify who is changes caused in features was increase advantages given t hree t han are in t he cells. by the of the cells. presence [1] t his [2] help advice t here in chromosome farmer Discuss ot her when condition extra condition. t hat t his in a one engineering in [3] Mutations i) t hem population a a roller? genetic Identify t he of is factors. crossing genetic chances b non- who t he [2] to a in variation. lead is woman your of organisms different how fat her non-tongue to t he between caused whose marries What who variation differences man roller. child genetic Genetic roller The division. in to uses advised his and Dave. of genetic disadvantages of [6] genetic agriculture. t hat profits. engineering [3] 311 835292 CSEC HSB Unit C.indd 311 08/01/2015 16:17 Unit D Disease D.1 Learning By the will end be on D.1 outcomes of able this topic define What and impact and disease you to: health its humans Health There ● and do are we two mean ver y by different health? ways of answering t he question ‘What is good disease health?’ ● classify diseases different into categories One ● differentiate between of and ● is exercise to how asthma a sor t getting of checklist over-tired, – the t he ability absence to of do a cer tain illness, and so amount on. respiratory The other The rst way state the possible treatment to ask people, ‘What does it mean to you to be healt hy?’ way might seem more objective, but healt h is increasingly seen as tract of we decide for ourselves. In other words, it is subjective. causes When and is affects something ● produce without symptoms explain the way signs asked, ‘What is good healt h?’ people generally give t he following asthma. sor ts of enjoy or answers: life, stressed The all World complete being having t he time Healt h inrmity’. Disease leading a and mental may condition of can be family, t he community, t hat an individual’s live, e.g. is hot, good studied be Healt h a clean, and infectious healt h of babies Ill healt h ● can result inheritance anaemia ● of and self-abuse, as is has a long from job or dened well-being, being not able to being tired occupation. healt h and malfunction life, pain, free of as ‘a from t he state of disease mind or or body healt h. levels: shelter reducing t he level by t he against t hat t he loving, t he t he It is is cool which t he to and mental responsible realise weat her t he and t he t hey signicantly accidents physical, caring, in when elements, of individual, impor tant community chance for of worldwide. home t he impor tance of at and affected children a free satisfying (WHO) nation aids risk of emotional adults cannot from: faulty alleles, Huntington’s e.g. a living being social various t he by The and and poor provides diseases. over-stressed. having well-ventilated healt h be at disease, family, dened healt h dr y, which physical from and Organization physical, to free friends from e.g. t hose for haemophilia, sickle cell disease cigarette smoking, excessive alcohol consumption, over-eating ● dietar y ● deciency, infectious ● diseases, degenerative personal and vitamin e.g. diseases, Huntington’s ● e.g. or measles, e.g. mineral deciencies inuenza, osteoar t hritis, dengue fever Alzheimer’s disease, disease social factors, e.g. loneliness, poor housing. Diseases p Figure D.1.1 Doctors do their best A to treat people when they are ill disease two diseases to keep and them offer advice healthy and is any change from normal healt h. Diseases can be classied into with groups. Communicable are infectious diseases like measles. They can support be passed from one person to anot her and are caused by pathogens, such 312 835292 CSEC HSB Unit D.indd 312 08/01/2015 16:19 Disease as and bacteria, are not its vir uses infectious, diseases, such Diseases are person as are and humans fungi. e.g. by feeling Signs are Health Non-communicable degenerative, diabetes, temperature Signs on e.g. detected feels, subjective. your impact sickle symptoms too what and cell see hot, an inherited anaemia and too obser ver t hat it is or can too and signs. cold and all Symptoms or t he diseases t hat deciency sick. e.g. can a see are what t he Symptoms doctor t hat may you are take have a rash. objective. p Written Figure D.1.2 sleeping swellings Different categories of disease World are classied in a great variety of different categories. T able a few of checks on this Health these categories. Make two for signs a list of human ● a list of disease examining woman’s neck. Organization an ambitious The (WHO) is campaign test for sleeping sickness and lists: reduce ● by D.1.1 to just nurse sickness coordinating Diseases A activity of lists disease rickets. feeling detect, high are nutritional and the number of cases diseases categories. Key terms ! Y ou are will probably nding within it nd difcult medicine, occupations of the to parts rst think of list of the easier to categories body, types compile of of than diseases, the second. think pathogens, of age, If you Pathogen specialisms sex people. the index of this book to nd different disease and their you have than D.1.1. lled one Y ou will several category, degenerative nd pieces e.g. disease. that some of paper diseases with Huntington’s All dietary disease deciency can your is be an lists, start classied inherited diseases are caused to transmitted (disease) by a Any pathogen into from one person that to complete another T able causing causes. is When disease Communicable disease Use A organism. and – an infectious disease. more disease and Non-communicable (disease) Any caused a disease that is not by a non-communicable. pathogen. Y ou may nd reorganising how q to easier as organise T able T ype it it of D.1.1 you to put your change table your in mind a spreadsheet, about the so you categories, can keep examples and it. T ypes disease of diseases with examples ✔ Description Examples Cause Scurvy A lack of vitamin C Rickets A lack of vitamin D Exam Asthma Dietary deciency Lack of nutrient a in particular the important diet an example communicable cannot Infectious is tip catch (communicable) else, Non-infectious measles. unlike of disease. it from the Make a non- You someone common cold sure know you or (non-communicable) which diseases are infectious Degenerative (communicable) and which are not Inherited (non-communicable). Asthma Ast hma is unlike cold a an example which of a disease usually lasts t hat for a people week or can have two. for During a long an time, ast hma ✔ bronchi and bronchioles become narrower as t he muscles in will The The overall linings effect is also t hat become t he inamed sufferer will and more wheeze, mucus cough and is be come across the terms t hem chronic contract. tip attack You t he Exam produced. shor t and Make sure mean and acute you use in this know them Unit. what in they your of answers. breat h. During bloodstream an will ast hma attack decrease. This t he is a volume of dangerous oxygen absorbed condition and can into lead t he to deat h. 313 835292 CSEC HSB Unit D.indd 313 08/01/2015 16:19 Health and Disease disease Causes The of causes include, a its impact on humans asthma of (substances substances and ast hma t hat found anxiety, Normal are cause in not fully allergies), fur and exercise understood, e.g. pollen, feat hers and (see genetic airway b but include tobacco Figure allergens smoke, D.1.4). dust Ot her mites causes and can factors. During asthma symptoms narrowed airway muscle (limited air flow) airway tightened wall muscles constrict airway p Figure D.1.4 moulds Dust (green) mites and feed organic on detritus on inflamed/ fibres. Their faeces (greenish spots) thickened are powerful allergens. The glossy airway brown spheres are their eggs wall (x40) mucus thickened muscle airway mucus muscle p Figure b) a D.1.3 person Diagnosis Diagnosis lungs using breat hed by of of t he t he p Figure D.1.5 Using a peak flow does a peak of a bronchus in a) a person who does not have asthma, asthma for meter lungs of measuring and muscle (Figure gives and t he D.1.5). an t he movement This air measures indication build-up of of of t he out how of t he much resistance to air is ow mucus. asthma several allergens, involves ow t he contractions are through have asthma ast hma out Treatments There Sections who wall steps e.g. by to not cope wit h keeping ast hma. pets and The by rst is cleaning to avoid your exposure home to regularly. meter Dr ugs can help alleviate t he inammation t he bronchial Figure of t he air ways t he symptoms, bronchial enabling e.g. tubes more air steroids and to t he get in are dr ug and used to reduce salbutamol out of t he dilates lungs (see D.1.6). 314 835292 CSEC HSB Unit D.indd 314 08/01/2015 16:19 Disease and Case Ast hma highest dust is a healt h rates of are on humans Health carried selected a t he t he t he in in t he worse when prevalence among Table between Prevalence adolescents of children D.1.2 in on and It t hat is African dust ast hma in of school September t he severity and Barbados widely ast hma ast hma shows Trinidad Caribbean. world. Caribbean, schools D.1.2 among problem questionnaire experienced. T able asthma ast hma in out high completed childhood much investigate was q and elsewhere children, To impact believed of Wheezing Number students in the experienced of asthmatic disease in the previous over on Trinidad and and attending t he Barbados, especially are Tobago, 35 December any of a study randomly 2002. symptoms in high. t hat Students t hey results. of asthma T obago study attacks one concentrations age and has symptoms, (all and the asthma-associated results are Trinidad Number past and study Saharan and its symptoms percentages) T obago 3519 1469 13.1 13.4 10.5 10.9 1.9 3.0 0.9 1.8 year the year 1–3 4–12 p more than 12 Figure asthma Lifetime prevalence helps Wheezing Asthma Family history of 24.1 24.3 12.8 13.5 23.0 13.4 asthma the D.1.6 A using person an because it who has inhaler. The relaxes muscles drug in bronchi African dust clouds reach the Caribbean from January to October. There has been evidence of increased amounts of Saharan dust being transported across the Atlantic to the Americas since the mid-1960s. The dust carries spores of the fungus, Aspergillus, which has been linked to causing asthma attacks. Since the 1960s, there has been evidence of increased numbers of patients with asthma attending accident and emergency (A&E) departments in Caribbean countries for the treatment of asthma. Sources Based vol. of on 25 information (2006) asthma Tobago: and among results of from Monteil Gyan et al. adolescents a al. Chinese Comparison in nationwide et the Journal of Caribbean cross-sectional of Geochemistr y, prevalence islands sur vey of and severity Trinidad (2005), BMC and Public p Health Figure D.1.7 viewed from Saharan dust storm 5(96). space Questions 1 What 2 Describe and 3 meant t he Tobago Explain is 4 is Explain ast hmatic term of shown t he in how t he results as how involved by t he in study and study Table could triggering dust prevalence? on be extended ast hmatic fungal childhood ast hma in Trinidad D.1.2. to nd out if Saharan dust attacks. spores could be involved in triggering attacks. 315 835292 CSEC HSB Unit D.indd 315 08/01/2015 16:19 Non-communicable (non-infectious) Disease diseases 5 Studies found t hat t here t he of should researchers dust. Why dust What is factors is t he t he in time are during t hat 6 have depar tments more when be people t here war y are of its of t he ast hma attacks? evidence in t he results t he impact attending increased drawing cause for and on humans A&E quantities t he involvement conclusion of genetic ast hma? Questions 1 State the 2 Make a table nausea and Learning By the will end be causes, this to topic discuss you the and diabetes and ● 4 State four 5 Describe prevention of: a possible and ● of the topic will temperature, your skin. of have two of having a a sign or symptom: headache, feeling tired asthma. possible referring already as asthma. causes explain involve following high on symptoms mellitus (types 1 is been index a condition covered in been to treatments for asthma. (non-infectious) several previous topics in diseases which various described. when Topic a person B.1.6 on is greatly page 89 over weight. when dealing The wit h condition body mass (BMI). 2) diseases. Maths will sick), rash each Obesity has ailments cardiovascular Y ou classify health. Non-communicable Obesity digestive ● three conditions obesity ● State This to of signs/symptoms, treatment ● of able definition (feeling having 3 D.2 outcomes WHO also explain be the able skills 1 to: importance of T able D.2.1 shows the estimated percentages of people in the Caribbean fitness who ● explain diet ● the and describe importance overweight importance obese in 1980, 1990, 2000 and 2008. q T able D.2.1 of Year stress and of exercise the were % management. overweight % obese -2 (BMI ≥ 25 kg m -2 ) (BMI ≥ 30 kg m ) Males Females 1980 25.3 29.0 4.8 9.2 1990 30.3 37.1 6.1 12.7 2000 37.0 46.4 8.9 18.8 2008 46.3 55.1 14.0 26.5 1 Plot the 2 Explain 3 What data on a suitable graph or Males Females chart. -2 in 4 the percentage of of BMI the ≥ male 25 kg m population was the the overweight, but not obese 1990? Make four conclusion 5 meaning Can any conclusions with link be data about taken made from between data the in table and support each table. gender, obesity and diabetes? 316 835292 CSEC HSB Unit D.indd 316 08/01/2015 16:19 Disease and its Digestive Gastric The t his is lined hydrochloric layer of is to Non-communicable (non-infectious) a and ver y t hick pepsin becomes layer from t hinner or of mucus. harming it. This prevents However, non-existent and t he its sometimes stomach’s it. acid burns This leads inamed. The t he to cause stomach gastric of lining ulcers, t hese is in of ten and t he which pepsin t he unclear, may stomach but t hey are lining known p Figure D.2.1 photographs to be inuenced by stress and alcohol consumption. A recently is t he alt hough bacterium of ten Helicobacter wit hout causing pylor i any t hat infects many Look to at show the two how our discovered waistbands cause diseases reduced. digest becomes wit h acid mucus hydrochloric begin humans ulcers resistance The on ailments stomach own impact have grown! In the 1950s people, and 1960s it very obesity was very rare, now symptoms. is common The treatment for gastric ulcers may involve drugs that reduce acid secretion or antibiotics to treat infection by Helicobacter pylori. These treatments are often successful, so surgery to remove part of the stomach is not used as much as in the past. Gall stones These form in the gall bladder when cholesterol becomes solid (Figure D.2.2). This can produce a number of small stones, or one large one, that can ll the ✔ Study tip entire gall bladder. This can be a very painful condition. See Treatments entire and gall var y, bladder. ultrasound bladder, but but to care include The use break has to of up be surger y to remove chemicals the gall taken to stone. with the gall stone dissolve the gall It how is possible much fatty to or even stone live foods the gradually without are in the a gall page about the bladder. into the It 78 to remind position stores of bile yourself the gall which ows duodenum. diet. Pancreatitis This is an reasons, inammation including pancreatic duct Eventually, even leak t he into Diabetes Diabetes B.3.4 enzymes t he body 1 and of t hese (from Summarising will nd complete and may and gall in t he t he pancreas to pancreatic where t hey t he for a which variety block of t he duodenum. juice can happen stone digest digest t he pancreas ot her and organs. have hear t covered in Unit B.5.4 on page 192 and circulation problems have been covered in activity diseases of been 146). information T able methods 2 disease information cardiovascular to This cavity type page Written Y ou t he mellitus type number Unit pancreas. consumption connecting Cardiovascular A of alcohol D.2.2 on in on obesity, earlier below. treatment non-communicable and diabetes sections The table of mellitus the should prevention. diseases (types book. show Find 1 and the causes, Y ou may come you may need 2) and information symptoms, across other p information which is worth including. If so, another Figure gall Y ou could head it ‘Further comments’ before you start lling in D.2.2 Gall stones inside the column. the bladder table. 317 835292 CSEC HSB Unit D.indd 317 08/01/2015 16:19 Non-communicable (non-infectious) Disease diseases q T able D.2.2 Causes, Disease symptoms and treatment Cause(s) of four and its impact on non-communicable Symptoms humans diseases Treatment/ prevention Fitness p Figure D.2.3 Swimming helps to build The up strength, as well as stamina words ‘tness’ same suppleness t hing. tness has However, t hree stamina and T able D.2.3 t hey mean t he increase tness generally refers to physical tness. Physical components. – movement in do muscle differ (see prepared you to power exibility, your in t he Table in at t hey enjoy, least If you on take stamina, up a slowly a range and to of for or can and form expect of to The impor tant take care. need week strengt h spor t you tness. probably times new before physical will natural D.2.4). weeks star t t hree maximum have you your to t he D.2.3). Figure several in stamina, breat hless (see D.2.3). for Figure having effects improvement you (see joints exercise somet hing get to 15 do or t he For exercise, see any activity more any t hing is lasting so minutes t hat on suppleness each q if Suppleness – improvement to as 3 to helps used Strengt h signicant Y oga sometimes 2 be D.2.4 are Stamina – endurance, the ability to keep going without gasping for breath. suppleness Figure ‘healt h’ 1 Activities p and and Consequences of different occasion. activities for physical fitness Activity Stamina Strength Suppleness Activity Stamina Strength Suppleness Activity Stamina Strength Suppleness Badminton ** ** *** Football *** *** *** Sailing * ** ** Canoeing *** *** ** Golf * * ** Squash *** ** *** Climbing *** ** * Gymnastics ** *** **** Swimming stairs **** **** **** (hard) Cricket * * ** Hill *** ** * T ennis Cycling *** *** ** Housework walking * * ** Walking * * *** Jogging **** ** ** (hard) ** *** *** ** * * * **** * (briskly) Dancing Weight- (ballroom) lifting Dancing *** * **** Judo ** ** **** *** **** ** Rowing **** **** ** Yoga * * **** (disco) Digging * = no real benefit; ** = beneficial effect; *** = very The beneficial effect; importance **** of = excellent diet effect and exercise Diet Diet is much such ver y impor tant sugar as and obesity fat and when will dealing cause wit h weight gain all t he and above. may lead The to intake several of too diseases, hyper tension. Exercise Regular exercise is essential for a healthy lifestyle. It will affect several parts of your body including the respiratory, circulatory, skeletal and nervous systems. 318 835292 CSEC HSB Unit D.indd 318 08/01/2015 16:19 Disease and its impact The immediate and dept h of It is B.3 and of effects excessive feeling making of to you exercise can more people even lead to be exercise, such in summarised t hat people shown in be for bad tiredness. likely to of ten Table It as an Topic in increase B.2.2. Figure ‘feel D.2.3 t he body. can even become nd life stressful. good for us, anxiety, Stress loss from Stress management of of stress stress or sleep, its The D.2.5, good’ are It all can af ter as in t he rate well as in doing to t he exercise. However, injuries immune or to a system, ill. cer tain be us amount aler t. about stress too irritability managing your is and life inevitable much so stress poor t hat and can physical you do not consequences. achieved coping of However, better in two wit h main t he ways, decreasing t he stress. p Figure D.2.5 The consequences If you are stressed because you do not have enough time to t you might decide to drop one of your commitments. If you are tr y you taking feel some members of your asser tiveness family classes or do not talking listen to to t hem you, you might unless explaining how excessive. ● improved as Some a to ● a Still so or meal feel to nd t hat if an t hat t hat evening day, are: lower heart rate fitness, and help, at include cannot e.g. what t he be suppose you you are blood ● improved ● increase ● improvement pressure respiratory in muscle in fitness size self-esteem following. perfect and set your to relaxing about t he help. in helps. problems to You ever yone music somet hing, could t he are tr y to family enough, such meet has a as for whet her new at chance least to talk day. in diseases are of are Caribbean many children, of increase and due iron in ot her common. concerned to Healt h anaemia inadequate from diabetes, obesity, par ts of t he world, aut horities nutrition-related t hroughout t he about: iron-deciency absor ption cancer can t hat as t he to out, so Caribbean, ● you t hemselves the aged t hat also enough could treating in rise t his good counsellor. practices t he admit not t hem a Health ● with talking be, study Caribbean are listening simply need nd ever y t heir chronic applying you cope Case t he and self-critical, or, ot hers about In exercise lower. nd friend clot hes one bit people Ot hers you strategies being sights strategies because Some Stop ● coping stressed doing. ● long-term of cardiovascular decreased ● are exercise feel. Learning get the The consequences such you long-term exercise stressed is because of ever yt hing beneficial, in, diseases long-term benecial. lead weaken unhappiness, is harmful can and A keeping management suffer amount are of considered (non-infectious) management may healt h. note per petual Stress Many exercise exercise of were Non-communicable B.4. interesting The humans consequences breat hing, consequences Units on in pregnant women and school- intake t he and poor iron in diet foods hyper tension, especially in t hose coronar y aged 35 hear t and disease, over. 319 835292 CSEC HSB Unit D.indd 319 08/01/2015 16:19 Non-communicable (non-infectious) Disease diseases In t he t he 1950s, t he due to diets people’s rened They sugar and more but The consumption contributed fast a Due to many a of result, children monitoring to Fur thermore, p Figure eating D.2.6 a Are healthy these young balanced diet people to to educate and in impact concerned This was Governments meat, on fats, humans about largely increased oils and diets t hat led attendance improved. led foods. fat, t hat have rich and in energy responsible sugar, for t he receive a to an proper and t he lifestyle of in diet. school initiative t he eating adopted met hods. attention the t he of improving planning span need children campaign for on balanced programmes status promotion popularity communities nutrition t here vegetables, self-help improvement preparation nutritional fr uits, focus A has addition, The to adequate and salt In grains, eaten. and increased and diseases. are t han restaurants The shor tcomings. and healthy diets energy too fast-food governments increased nutrition are in largely cereals, Parents School t he of less many menus improved wit h poor t hat are of children parents diets chronic beans) children. a to processed and t hat problems saturated has exhibit promote initiatives above. amount resources good fats, t hese ensure improve a to listed and programme’s class were region. making ot her refers in young involving school in t he protein. by proliferation t he (peas school-aged t he a high in t he schools Dominica in refers impor ted increase legumes in only also seen programmes of not bullet meals t he insufcient feeding habits of to Caribbean nutrition decades saturated costly among nutrition as reduction and foods has on and intake and recent second Caribbean t he its available. such t he dependency tubers energy Malnutrition in been in energy healt h over nutrients, diseases affected Malnutrition nutrients. As people and introduced emerged. in of t hat decient protein nutrition, has governments malnutrition and must of the constant involved. be designed population at large. at The governments of t he Caribbean have come toget her under an school? initiative toget her called t hrough providing each Caribbean ve are policies challenge to is eating habits giving simple can do ● ● ● ● ● ● ● to Eat larger Eat less Use Choose of oily, salty fewer more Drink little more to t he of and diet and fr uits foods, salty foods our in most training, food paid to each countr y. foods is a goals of t he and impor tant Here closely list t hings of The t he is t hings we healt h. coloured barbequed vegetables. foods. seasonings and The nutritious t he work education attention population. and and of of They research. oppor tunities One whole Healt h. ser vice, and availability greasy sweet care economic our amounts salt, wit h t he in activities: population. improve Drink Be t he advice fatty, less and improve of coordination analysed, agricultural all types information, countr y Cooperation and salty snacks. drinks. water. or no alcohol. physically active. 320 835292 CSEC HSB Unit D.indd 320 08/01/2015 16:19 Disease and Based on (1998). its impact on information Cajanus, the humans from Non-communicable Assessing Car ibbean Food Dietar y and Trends Nutr ition in t he Quarterly (non-infectious) diseases Caribbean 31(4) Questions 1 How did intakes 2 3 in Suggest and governments t he two reasons t he 4 Explain 5 State Caribbean 6 Describe 7 Describe would for t he rise in anaemia of iron in t he is meant by t he nutrition-related in t he population recent steps term diet cases of protein and energy in pregnant women pregnant women and t hat disease. have increased in t he decades. taken by governments t he Caribbean. how you would make chronic diseases of you increase children. what t hree Caribbean children. impor tance school-aged t he 1950s? school-aged Explain in sure set t hat up all a t he school to improve feeding children t he diets programme. benetted from of t he How it? q T able D.2.4 Questions Year Death per Use other topics/sections in the book when answering these Death rate per 100 000 questions. females males 1 Which activity in T able D.2.3 do you think is best for all rate 100 000 round physical 1985 28 41 1990 40 57 1995 43 59 2000 54 72 fitness? 2 Suggest minute why when 3 State the 4 State two 5 In point of regular 8 exercise the three person is to at components ways form leads of list a coping the the heart beating fewer times each rest. of with fitness. stress. positive outcomes and b the negative outcomes exercise. T able D.2.4 1985 and shows trends in diabetes mortality in the Caribbean between 2000. a Plot the data b Describe c Calculate the the on a suitable death rate in percentage graph. females increase between in the 1985 death and rate a 2000. for males and q b for females between 1985 and T able D.2.5 2000. Condition d Suggest why females have a higher death rate from diabetes % deaths % deaths in 1980 in 2000 than males. Heart 9 T able D.2.5 1980 and shows the major causes of death in the Caribbean between disease Cancer 20 16 12 15 4 10 11 10 Diabetes 2000. Stroke a Plot these data on a suitable graph. Injuries b Which causes of death have increased in c Which causes of death have decreased this in period? this and 8 7 violence HIV/AIDS period? No data 6 available d Why do you think there was no data available for HIV/AIDS in 1980? Hypertension 6 6 321 835292 CSEC HSB Unit D.indd 321 08/01/2015 16:19 Communicable (infectious) Learning By the end Disease diseases D.3 outcomes of this topic Communicable be able describe the causes, symptoms D.3.1 of a range the of treatment describe and acute a range of effects transmitted on her are what causes controlled. t hem, Note how t hat t hey are inuenza, are classied as acute respirator y infections. and is is one over t hat usually comes on suddenly, has clearly dened quickly. Gastroenteritis the of the is inammation of t he stomach and intestines. Diarrhoea, infections pregnant (nausea) and abdominal pains may result. Causes are infections mother by and diseases, t hey infectious sickness (STIs) of how bronchitis infection Gastroenteritis sexually range and diseases ● a t herefore diseases symptoms control diseases of An explain humans diseases shows and pneumonia infectious ● on signs treated and impact to: Table ● its you Infectious will (infectious) and food and water-borne pat hogens and irritation of t he lining of t he foetus. alimentar y cause q T able D.3.1 Disease t his The canal by some foods and dr ugs. Typhoid and cholera bot h can condition. features Causative of six communicable diseases, including control Symptoms and treatment Spread Signs Control Treatment Droplet Shivering, Headache, Flu infection raised fever, good warmth, ventilation drinks, organism Inuenza Virus body temperature sore throat Rest, vaccine, hot pain killers Tuberculosis Spores Coughing, Fever, Avoid in spitting sufferers overcrowding, tuberculosis infection blood become droplet and Pneumonia Ringworm Antibiotics Bacterium Mycobacterium Bacterium Spores Coughing, Fever, Pneumococcus in sputum chest droplet infection red Fungus Spores Red Tinea oors, on towels, is thin pain in on Avoid Antibiotics Thoroughly Fungicide dry ointments skin. sources body skin spitting, vaccine overcrowding Itching patches avoid BCG pale Avoid (antifungal of drugs) infection, e.g. changing rooms Cholera Antibiotics Bacterium Contaminated Vomiting, Gastroenteritis Proper Vibrio water severe where disposal diarrhoea intestines of are chlorination cholerae particularly by faeces inamed, stomach pains faeces, drinking of water and dehydration T yphoid Gastroenteritis Contaminated Severe water diarrhoea, treatment fever, both food and rash Antibiotics Proper Bacterium Salmonella and of water food, vaccination 322 835292 CSEC HSB Unit D.indd 322 08/01/2015 16:19 Disease and its impact on humans Communicable (infectious) diseases Bronchitis Bronchitis causing is a more condition mucus to where be t he bronchi released. This and can be bronchioles treated and are inamed, cured. Study ✔ However, See bronchitis is a condition of ten found in people who smoke. The Figure damages cells lining t he bronchi and bronchioles. Goblet more mucus and fewer cilia work to get rid of t he yourself on about page the 98 to goblet cells cells produce B.2.1.4 cigarette remind smoke tip mucus. and cilia in the lining of the The bronchi. result is hence long t hat t he mucus term lasting, accumulates ‘smoker’s severe in cough’. infections. t he air ways Bacteria This is can referred and has to be now t hrive to chronic as coughed here and (long up, cause lasting) bronchitis. Sexually Each year sexually and be sexually worldwide. transmitted foetus not life As by some t he t he enough. can if and, Treatment, condential (see term also be at some whet her Figure – suggests, treated in infections (STDs) contact, placenta t hreatening embarrassment diseases sexual STIs across infections transmitted transmitted However, to transmitted (STIs) (STIs) affect a sexually normally and in However, cases, sterility a doctor people or if ot her not a known t he as Caribbean infection can intercourse. ways, breast t hey at in transmitted t hrough early. by commonly sexual transmitted bir t h – many can e.g. milk. cause dealt special wit h from Most mot her STIs are discomfor t, quickly clinic, is always D.3.1). p STIs are caused by a wide variety of organisms Figure about ● their doctor vir uses – genital her pes, genital war ts and D.3.1 People concerned including: or sexual health specialist can health visit clinic a in HIV/AIDS confidence ● ● ● ● bacteria fungi – – chlamydial infection, syphilis and gonorrhoea t hr ush protozoa – trichomoniasis ar t hropods – e.g. pubic lice, also known as ‘crabs’. Did you know? ? Gonorrhoea Many Gonorrhoea is caused by a bacterium which lives in t he cer vix, a urinar y scientists vaccine success. tract, mout h and rectum. In women, t he disease can spread to t he oviducts, causing pelvic inammator y disease. This can result are HIV , They trying so are far to nd without looking for a ovaries vaccine and for that will promote the in production of antibodies that infer tility. attach The early include or a penis. t he symptoms burning involves a resistant to ver y many hard course infection sensation However, disease of of to on t he bacterium urination people control. antibiotics. by have no and a are discharge symptoms Treatment However, is mild at some strains from rst relatively and may HIV t he However, which vagina makes straightfor ward of t he to bacterium and and number of t he most commonly used antibiotics. wit h education ot her kissing. STIs, and by t he gonorrhoea However, pregnant use of cannot women condoms be caught can is essential. from transmit toilet t he In HIV are many the world. it envelope infecting is one viruses different The of the and most there strains best of cells. across vaccine are HIV would inactivate all Prevention HIV t hrough outer stop changeable against a the strains, but the reality is that common seats or bacterium to antibodies against are not one strain by usually effective against t heir others. unborn children. 323 835292 CSEC HSB Unit D.indd 323 08/01/2015 16:19 Communicable (infectious) Disease diseases Genital Exam ✔ term carrier was used in inheritance. Here blisters it in a T ake care humans slightly different during As you use sexual it genital her pes which can are itching lead to in ulcers. t he area Genital followed her pes is by a rash. passed is activity caused by a and t he vir us infection t here is no can be passed complete cure. to t he newborn Prevention is by context. avoiding how of appear is child. used on the on on impact herpes symptoms Later, section its tip The The and the contact wit h a known sufferer. Once again education is ver y term. impor tant in t he drive to reduce t he number of cases. envelope HIV/AIDS HIV is t he because and it t hus Immune t he new HIV p genetic material Figure D.3.2 genetic copies The material, of protein (RNA) itself virus RNA, inside HIV to t hem ill and lymphocytes, These in disease-causing becomes (Figure system D.3.2). to It is become microorganisms. eventually develops so-called decient When AIDS t his (Acquired Syndrome). Eventually only off vir us immune HIV t he t hus takes weakening over lymphocyte travel to and breaks uninfected our turns immune it open, into a releasing lymphocytes, system. factor y for HIV hundreds attacking and turn. identied in 1983. By 2001 t here were approximately coat uses make human was human’s lymphocyte, vir uses. infecting viral person a a ght human inside production. of to Deciency attacks Once Immunodeciency causes unable happens, HIV Human of ten its more 35 million be spread receiving people by world-wide sexual blood infected intercourse from someone wit h wit h t he someone infected wit h vir us. HIV infected HIV (e.g. can wit h only HIV, t hrough a by cut, cells sharing needles reasons) or from Unfor tunately, against many HIV, HIV vir us t he various The key t heir to into by diseases t he a contact wear play) These it to reducing t he receiving her effective improved dr ugs replicating. wit h for medical offspring. available, have blood t he slow Ot her AIDS vaccination life expectancy for t he progression of dr ugs tends are to used develop to treat t hrough system. HIV of par tners infection HIV and People getting to someone of infected and HIV by widely from spread HIV. or anti-retroviral which The wit h no immune sexual gloves and still prevention barrier wit h treatments preventing fewer as is dr ug damaged to injection mot her t here but behaviour. have ser ve to a a dr ug patients. t he having for can for be more should blood (t hrough people of in be by to cuts use among like to people to change encouraging condoms prevented measures wit h needles educating people also spor ts sharing is prevented from people off who which coming urging come people dentists t he eld inject of dr ugs intravenously. Typically, t he rst infected it takes several symptoms wit h HIV Someone infected known a as People who if are t hey do or not years AIDS. can infect wit h for someone Unfor tunately, HIV, many but ot her who infected t his people does not wit h means wit hout show HIV t hat any to develop someone realising it. symptoms, is car r ier. t hink HIV have remote of t hey positive access to may or clinics communities. be not. A infected Many where person wit h such t hey who HIV people can be knows should have do go not tested, t hat as t hey t hey are a for test to see testing, live in infected or poor wit h 324 835292 CSEC HSB Unit D.indd 324 08/01/2015 16:19 Disease HIV t he and may not STIs whose of to humans admit many STIs can be mot hers vir us during The in on t his Effect as t here communities. is This a social makes stigma seeking associated medical of vectors on human health wit h help difcult. Effects Most impact wish condition more t he its at STIs to t he or cause passed are bir t h. breast on from affected Disease and mot her by can t he to HIV also foetus foetus. vir us cross A high become from t he percentage infected mot her to by t he of babies receiving baby feeding gonorrhoea foetus mother via t he and syphilis placenta. abnormalities, e.g. are This eye caused can lead by to bacteria deat h of and t he t hey baby can pass (stillbir t h) defects. Questions 1 Explain the difference between communicable and non-communicable diseases. 2 State help 3 two ways slow Make a the table chapter. Use in which spread to of show the getting dentists wear protective gloves can HIV . information same to column about the headings as STIs in mentioned T able in this D.3.1. p Figure D.3.3 reflected (b) D.4 Effect of vectors on human health St. in T wo in of (a) HIV/AIDS Belize and Vincent Learning By views posters the end outcomes of this topic you Malaria will Malaria is a tropical disease caused by a protozoan called D.4.1). The parasite needs a female mosquito able called Anopheles to discuss a vector (a carrier) and carr y it from person to person. The life cycle is complicated and is summarised in Figure D.4.3. Notice describe A female and mosquito injects saliva Plasmodium infect ● The ● ● red takes wit h enters blood feeding form malaria the life cycles body of mosquito and a blood meal Plasmodium from into t he a person person’s who is uninfected ● explain forms gametes in which female and mosquito t his liver cells where it reproduces blood cells the of housefly vectors importance and blood. and t hen leaves of controlling vectors. to t he red enter mosquito t he takes becomes (see Figure D.4.1) and divide to plasma. a blood infected ✔ meal wit h from t he an infected gametes of fuse and anot her reproductive stage occurs Study tip person The mosquitoes and Anopheles Aedes aegypti Plasmodium. of gametes roles cells. Anot her The the describe methods ● of on stages. ● ● fever the the following effects dengue of ● Plasmodium the act and as to: Plasmodium ● (Figure be wit hin disease. are insect They have have to vectors similar life t he cycles and lay their eggs mosquito. in ● The to infective take stage anot her moves blood to t he salivar y glands to wait for t he mosquito water. Make differences sure you between learn the them. meal. 325 835292 CSEC HSB Unit D.indd 325 08/01/2015 16:19 Effect of vectors on human Disease health The main symptom temperature even can 41 °C. of ten attacks A of from Whilst and dr ugs quinine. malaria up periods fatal. fever number being These be of of shoots of have a adults been high normal fever weakness Ot hers is its recur rarely for fever. of ever y few die, impact affected 37 °C t hey its to days. humans person’s around In on 40 °C children continue to suffer malaria, t he or t hey periodic years. developed include The value and against mepacrine and stage Mosquito longest used paludrine. in liver Human red blood cell liver p Figure D.4.1 Plasmodium, a structure the stage The of protozoan, which which its cell causes varies malaria, depending lifecycle. In this has on electron blood micrograph you can see the stage that stage infects red blood cells. T wo salivary parasites glands have infected this cell (x 5000) fertilisation male gametes gut p Figure D.4.2 mosquito A female taking a blood Note transmitting how full its of cells inside and containing female male gametes mosquito meal and Figure D.4.3 Life cycle of the parasite which causes malaria Plasmodium. abdomen is with Dengue human female Anopheles p possibly and released fever blood Dengue carried fever by the the names ve and and a fever which seven rash. The along aegyptii with rash with is severe and the form There are or pain feet caused four DEN-4.The legs is types fever in the three the haemorrhagic from the nose, term Because it is treatment and t his given It given is to gums of a the for muscles four form and vir us and can below vir us is given between days – that joints, af ter also the the cause skin. bleeding.) caused for be necessar y). be for by lasts or – medical not Caribbean headaches, on bleeding rest the mosquito. severe the in DEN-3 appears more (Haemorrhaging prevalent DEN-2, days This star ts. vomiting Aedes DEN-1, is by a vir us condition. plenty wor t h of The uids noting sufferers t here wit h is no specic patient must (intravenously t hat t he aspirin if should haemorrhagic adult form eggs as it ‘t hins’ t he blood reducing t he chances water t hat it will clot. pupa Dengue larva factors is mosquito p Figure D.4.4 transmits the Life cycle malarial of Anopheles, the mosquito vector which Public an emerging contribute to controls healt h disease. t his. in most systems to A There number are no countries detect and of effective wit h dengue. control parasite epidemics are deteriorating around t he world. 326 835292 CSEC HSB Unit D.indd 326 08/01/2015 16:19 Disease Rapid has and its growt h led to of cities on humans in tropical overcrowding, substandard mosquitoes The impact sanitation, to increase live in urban Effect to water more breeding and sites for tyres mosquitoes. human health surface breathing more tube people. non-biodegradable discarded on and plastic eggs in packaging vectors countries decay allowing closer of makes Air laid water new travel larva mouth helps people infected wit h dengue vir uses brushes to move easily from city to city. antenna Vectors antenna future of image A vector is an organism that carries a pathogen and transmits it from one host to another. adult Often vectors carry the pathogen on their compound feet or in their mouthparts. Some pathogens eye complete their life cycle in the body of the vector as happens with Plasmodium pupa Ot her common and rats. Life cycle vectors are houseies, birds female of p Figure D.4.4 feeds on blood Anopheles shows t he life cycle Figure D.4.5 transmits of the Life cycle virus that of Aedes causes aegypti, dengue the mosquito vector which fever Anopheles. Life cycle Figure D.4.5 transmits she Life of Aedes shows dengue aegypti t he various fever, where stages t he of t he female life can cycle pass of on t he t he mosquito vir us to t hat people as feeds. cycle of the housey The common housey can carry a number of disease-causing organisms including the bacteria which cause food poisoning (Figure D.4.6). eye mouth onto – enzymes food which are regurgitated partially digests it. antenna Disease-causing organisms may be proboscis deposited onto the food. p Figure D.4.6 Houseflies can transmit diseases eggs are rotting laid on bodies of animals adult Study ✔ tip pupa egg The use of insecticides the selection of are resistant. This in a way similar antibiotic has mosquitoes to led to that has happened the evolution resistance in of bacteria. larva See p Figure D.4.7 The life cycle of a Figure C.4.12 on page 294. housefly 327 835292 CSEC HSB Unit D.indd 327 08/01/2015 16:19 Effect of vectors on human Disease health Control The main of vector-transmitted met hod of control is to attack and its impact on humans diseases t he vector. Malaria Despite of t he helped ● countless world’s to control Spraying t he mosquito ● Draining ● Using of ten p Figure in D4.8 Mosquito insecticide have nets proved soaked method but have they to to a be control used breeding t he of serious dollars diseases. having been However, spent, t he malaria following is still measures one have it. wit h oils. insecticides grounds This breeding evolves insects, to (marshes t he grounds kill resistance including kills t he to some of t he t hat by waters) of t he suffocation. Unfor tunately, pesticides are stagnant lar vae mosquito. mosquito. t he and mosquito which benecial to also t he kill mosquito many ot her humans. very ● effective millions most malaria Using biological control by introducing a predator, such as guppies - (a properly ● sh) to eat Preventing mosquito Dengue Control t he t he nets mosquito female lar vae. mosquito impregnated from wit h biting insecticide people, placed e.g. by over t he use of beds. fever of mosquito dengue t hat is fever is t he same as in t he case of malaria, in t hat it is t he controlled. Gastroenteritis By removing, help p Figure D.4.9 An electron achieve Leptospira, the bacterium leptospirosis sewage ies, gastroenteritis should be removed will and occur less treated, of ten. garbage To cans have tightly tting lids and be cleaned regularly, r ubbish should that be causes reducing micrograph should of or t his placed in plastic bags and sealed, r ubbish dumps should be carefully (x5000) managed, and food should insecticides be should covered be used to to avoid kill contamination, and y traps houseies. Leptospirosis Leptospirosis mild inamed failure into Ot her The Figure D.4.10 from broken t he disease A brown are drainage rat notoriously they are so difficult environments such as well we sewers make symptoms can muscles, include be mild nausea, liver or severe. vomiting damage, The and jaundice, kidney bleeding. t his disease and may help to be rats. dr unk domestic antibiotics are education, infect strict so enter animals, as rodent t hat contaminated or When it is a t he can are rats urinate, body carr y bacterial control, people t he via of cut t he of risks in bacteria t he skin. bacteria. infection. vaccination aware a t hese t he Ot her domestic of swimming water. study Rats control adapted and Symptoms aching emerging pipe. to severe responds potentially disease. fever, including which Dengue as The water and Case a bacterial include internal animals, animals p a causing met hods in eyes. and Bacteria get is symptoms for to fever the them, Dengue, a mosquito-borne vir us t hat causes high fever, nausea and drains painful Latin and body aches, America. migration, is reaching Changing have epidemic weat her increased t he levels patterns, number as of in t he well as cases, Caribbean increased according and tourism to t he 328 835292 CSEC HSB Unit D.indd 328 08/01/2015 16:19 Disease Pan and its American t he wettest The vir us, ridden rash, into by impact a severe the of humans Effect Organization year has week for four most (PAHO). countries distinct strains, with painful u-like headache, muscle and more internal usually Healt h time which for on severe and and external amongst young dehydration if they includes bed rest Wit h vaccine do and adults not receive hydration. fatal keeps children. prompt Severe such Some of cases these Victims can high available, public healt h campaigns to control mosquitoes. form marked can are also which fatal, die from normally require hospitalisation. rely fumigation exper ts on Figure D.4.11 Infection by one strain provide immunity against infection by anot her. In fact, a house people at wit h one greater or risk more of strains of developing t he vir us dengue are fever t hought if infected t he Rico State Epidemiologist commitment and par ticipation prevent and dengue mosquito can reproduce Dengue P revention and Control climate change patterns rainy control t hat in a have seasons, dengue as as dengue. result recent of increased t he Enid reasons of Given in at Garcia all t he Rivera sectors amount astonishing to put a vapour called the Amer icas , a warming, as for intensity t he and increase of rain repor t ‘We to t hese well by as be need able days, t he PAHO, cyclical duration
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