1.3 Micro-organisms:
Micro-organism: Living organisms that are only visible with the use of a microscope.
These include bacteria, viruses and fungi.
Parasite: An organism that gains nutrition from a living organism (the host). It usually
lives in or on the body/cells of the host – which is usually harmed to some extent.
Saprophyte: Bacteria or fungi that gain nutrients by feeing on dead or decaying organic
material
Heterotrophic: Micro-organisms that obtain their organic material from other living
organisms. These can include saprotrophic, mutualistic, parasitic or communalistic
bacteria.
Autotrophic: Micro-organisms that do not need to rely on other organisms for
nutrition, they instead make their own food usually through photosynthesis.
Mutualistic: Where the bacteria feeds off the host, however both receive benefits –
the host is not generally harmed in the process. E.g. gut bacteria
Communalistic: Where the bacteria benefits from the relationship but doesn’t help nor
harm the host.
Bacteria: Single-celled organism, classified according to their shape (cocci – spherical,
bacilli – rod-shaped, vibrio – comma-shaped, spirillum – spiral-shaped). Found living in
the soil, water or as parasites/saprophytes of plants and animals. The parasitic forms
cause many infectious diseases. They carry out binary fission for reproduction and
extra-cellular digestion for feeding/nutrition.
Cell Wall: A rigid structure surrounding the plasma membrane of bacterial cell, helps
give the bacteria its shape, offers the inside of the cell protection.
Flagellum: Long whip-like tail/structure used for movement of the bacterium, to get
away from unfavourable conditions and towards more favourable conditions – like
space, nutrients and less predators.
Plasma Membrane: Semi-permeable layer that controls the entry and exit of materials,
into and out of the cell. In = nutrients (glucose) + oxygen. Out = CO2, water and waste.
Slime Layer: Protects the bacteria from white blood cells and harmful viruses, helps
prevent dehydration and assists the bacteria in sticking to surfaces.
Nuclear DNA Material: Carries the genetic code/material of the cell. DNA is a closed
loop.
Cytoplasm:
Ribosome: Particles which produce protein inside the cell.
Binary Fission: The process by which prokaryotic organisms divide and reproduce
asexually – which is how most bacteria reproduce. Their genetic material is replicated,
the cell elongates towards the cell ends, the cell membrane pinches together and a
septum forms down the middle of the cell, then the cell divides into two equal
daughter cells (cytokinesis) each containing a copy of the chromosome. As this process
occurs, the bacterial population increases exponentially and the bacteria start to
occupy the surrounding space. Bacteria can reproduce around every 20 minutes and
throve in warm/moist conditions. Warmth is vital in reproduction as is speeds up the
chemical reactions and metabolism in the micro-organism increasing the rate of
feeding/reproduction.
Bacterial growth lag phase: Growth number is slow as they become used to their new
environments and nutrients.
Bacterial growth exponential phase: In this phase the bacterial cells have unlimited
food, space, oxygen; most survive – therefore reproduction is at a very right rate,
numbers increase exponentially
Bacteria growth stationary/slowing phase: Some or all of the resources start to
become limited and increasing numbers of bacteria do not survive to reproduce;
reproductive rates slow – numbers do not increase at as great a rate.
Bacterial growth decreasing phase: Some or all of the resources are limited and toxic
waste products affect bacteria. Many bacteria do not survive to reproduce, so the
reproductive rate is less than the death rate – numbers will decrease.
Fungi: Heterotrophic, non-motile (non-moving), non-photosynthetic and chiefly multicellular organisms that absorb nutrients from dead or living organisms. They include
mushrooms, moulds and yeast. They grow on top of and down their food source. Each
type of fungi can only grow on certain substances. E.g. bread mould can’t grow on
human skin, etc.
Hyphae: Thread-like structures that are used for support and feeding (extra-cellular
digestion)
Spores: The reproductive cells that carry the genetic code/DNA to reproduce another
identical fungus. They are small and light, so that they can be carried a distance by
wind/water/animals to land and germinate.
Sporangium: Sacs that produce spores – when spores mature, sporangium burst,
releasing the spores into the air (which are needed for reproduction).
Sporangiophore: Holds the sporangium up high allowing for more exposure for wind,
water and animals for dispersal.
Mycelium: The entire structure/network of the fungi.
Extra-cellular Digestion: The process in which microbes such as bacteria and fungi feed
by secreting digestive enzymes through the cell membrane into or onto dead/living
matter. The enzymes catalyse the break down of larger molecules into smaller
molecules that can be reabsorbed by the fungi/bacteria through the cell membrane
using either passive diffusion, active transport or phagocytosis. This digestion occurs
outside of the cell, taking place in either the lumen of the digestive system, a gastric
cavity/other digestive organ or completely outside the cell. Bacteria do this by
releasing enzymes through the cell wall, digesting food molecules outside the cell and
reabsorbing the nutrients. Fungi do this by releasing enzymes through the wall of their
hyphae, digesting food outside the cell and then reabsorbing the nutrients. The
nutrients must be broken down or they cannot travel through the plasma membrane.
The nutrients collected can be used in the process of respiration, fuelling metabolism
to create energy for life processes.
Microbe Respiration: Respiration is the process where food is broken down, with or
without the presence of oxygen. After bacteria and fungi obtain food via extra-cellular
digestion, they create energy from food. This energy can then be used for movement,
growth and reproduction. Respiration is the process in bacteria and fungi where
organic substances are broken down to simpler products with the release of energy –
used for other metabolic processes. There are 2 types:
-
Anaerobic Respiration: Respiration without the presence of oxygen.
Equation (Bacteria): Glucose  lactic acid + carbon dioxide + little energy
Equation (Fungi): Glucose  alcohol (ethanol) + carbon dioxide + little energy
LESS EFFICIENT AT GENERATING ENERGY
-
Aerobic Respiration: Respiration with the presence of oxygen
Equation (Bacteria/Fungi): Glucose + Oxygen Carbon dioxide + water + lots of
energy
*Only in an environment with moisture, food and warmth.
MORE EFFICIENT AT GENERATING ENERGY
-
In an oxygen rich environment, aerobic microbes will outcompete anaerobic microbes,
however as the environment becomes depleted in oxygen and conditions become
toxic, the anaerobic microbes will dominate.
Yeast in food: A microscopic, single-celled fungi that feeds on glucose (a sugar) and
respires anaerobically (without oxygen) or aerobically (with oxygen) to make two
useful products of carbon dioxide alcohol during the process of fermentation.
BREAD MAKING EQUATION: Sugar (Glucose)  Carbon dioxide + alcohol =
fermentation
Yeast feed on the glucose, CO2 bubbles created makes bread rise, alcohol evaporates
due to the heat from the oven.
GINGERBEER MAKING EQUATION: Sugar (Glucose)  Carbon dioxide + ethanol =
fermentation
Yeast feed on glucose, CO2 bubbles produced make drink fizzy, ethanol makes it a
alcoholic drink
Bacteria in food:
CHEESE MAKING EQUATION: Lactose (sugar)  lactic acid + energy (Anaerobic
respiration)
Bacteria feed on the lactose in the milk, Lactic acid give the flavour (clumping proteins)
– the longer the bacteria are left to make the cheese the riper/shaper it tastes.
YOGHURT MAKING EQUATION: Lactose (sugar)  Lactic acid + energy (Anaerobic
respiration)
Bacteria feed on the lactose in the milk, lactic acid give the yoghurt the sour, tangy
taste which lowers the pH level and cases the milk to curdle and prevents the growth
of other pathogens. The energy gained relates to the immediate reproduction of
bacteria which causes the yoghurt to thicken (binary fission).
*Cheese and yoghurt making are dependent on the life processes of certain varieties
of bacteria. Any harmful bacteria in the milk are first killed by heating the milk
(pasteurisation). The starter bacteria are added – which feed on the lactose sugar in
the milk, changing it into lactic acid. This makes the milk acidic (lowers pH), giving it a
sour taste and causes the milk to separate into the solid part (curds) and the liquid
parts (whey). Both the curds and why can be further treated by other bacteria (and
fungi) until they become a variety of different milk products (cheese or yoghurt)
Effect of environmental factors on the life processes of Bacteria and Fungi:
Temperature: Enzymes involved in all life processes are denatured at very high
temperatures or their activity is slowed at very high temperatures. This means
nutrients are not digested and respiration does not occur, leading to insufficient
energy for all other life processes – growth/reproduction/excretion.
Oxygen: Bacteria and fungi which are anaerobic will die if there is insufficient oxygen
for respiration.
Nutrient Availability: Micro-organisms need sufficient sugars (glucose) for respiration
which produces energy. All other life processes are affected if there is insufficient
energy for them to be carried out. Micro-organisms need sufficient proteins as well to
grow growth, repair and replacement of new tissues. Growth and reproduction will not
occur if nutrients aren’t available.
Moisture (water): All living cells require a moist environment because essential cellular
reactions such as respiration occur within the liquid cytoplasm (which is about 80%
water). Lack of water causes desiccation (drying out) and death of microbes. Water
also helps maintain the conformation of the active sites through hydration for some
kinds of enzymes.
pH Level: Change in pH level whether it be too acidic or basic/alkaline my affect or
denature digestive and respiratory enzymes, with a consequential affect on al other
life processes.
Chemicals (E.g. Disinfectants): Disinfectants generally cause the death of microbes,
which in turn means that no life processes can occur.
Antibiotics: Many antibiotics affect the growth of bacteria because they prevent
protein production
Competition: Often several types of microbe compete for resources such as nutrients
and oxygen. Once available nutrients and/or oxygen have been used up, the rate of
respiration, growth and reproduction of the microbes decreases. Some bacteria and
fungi excrete toxins that cause other bacteria and fungi to die – these toxins have an
antibiotic function.
The Culturing of micro-organisms: Agar Plates
-
-
Culturing agar on plates: Bacteria and fungi will survive and reproduce on an
agar plate as the conditions provide food, moisture, nutrients and space which
allows them to respire, giving them the energy for all of their life processes.
Viruses cannot grow on an agar plate as they require a living host. Once the
bacteria and fungi colonies have grown, the bacterial colonies will look
slimy/greasy/shiny whilst the fungal colonies will look fuzzy/furry.
Preparing an agar plate: The inoculating loop (swab) is sterilised so that only
those microbes present on the surface of the sample will end up on the agar
plate. The lid of the plate is open only for a short time to prevent other
microbes in the surrounding air, settling on the agar. The plate is then stored
upside down as microbes produce water as they respire aerobically and
reproduce, so being upside down means that the micro-organisms don’t drown
(die). Inverting the plate means that the water will drip onto the lid. 30 Degrees
Celsius is the optimum temperature for microbe’s life processes, including
respiration that gives the energy required for reproduction.
Composting: The process by which saprophytic (decomposing) bacteria or fungi feed
on dead, decomposing and decaying material to produce compost. Composting is
important because it allows nutrients to be recycled using waste which can be used to
improve the growth and health of the plants we eat and grow in our gardens. When
decomposers are provided with the right conditions, they digest organic matter,
releasing carbon dioxide and nitrogen to the soil and air. Compost bins are used to
speed up microbial delay. Optimal conditions include:
Oxygen: Needed for aerobic bacteria or fungi to carry out aerobic respiration which
produces compost that is high in nutrients and doesn’t smell (organic matter + oxygen
 water + carbon dioxide + energy). If oxygen is limited, the decomposers respire
anaerobically producing low quality compost and noxious, pungent gases.
Warmth: Needed to keep decomposers active. As the decomposers respire, they
produce heat energy that makes the compost warm and provides an environment that
will allow certain bacteria and fungi to live. To keep heat, the compost bins need to be
kept in a warm place (not too hot) and if possible a cover over the top to trap the heat.
Water: Too much water creates anaerobic conditions, too little and the decomposers
will die, therefore the compost should be kept moist at all times.
Suitable pH Level: Compost tends to be acidic as decomposers work, as during the
initial stages of decomposition – organic acids are created. So, some lime can be added
to neutralise the acidity, lime is a rock powder used to raise the pH levels in highly
acidic soils.
A variety of nutrients: Carbon and nitrogen should be added to the compost so the
decomposers can remain healthy and working.
Decomposers: Bacteria and fungi that obtain energy from the chemical breakdown of
dead organisms or animals or plant waste. They secrete enzymes onto dead matter
and then absorb the breakdown products. Feed on organic matter and use
glucose/carbon compounds in dead organic matter as an energy source for respiration
that releases CO2 into the atmosphere.
Viruses: Very small, visible only with an electron microscope. A non-living organism
that cannot survive without a living host to reproduce. Out of all of the life processes it
can only reproduce. Made up of two main parts: Genetic material (DNA/RNA) which is
surrounded (for protection) by a protein coat/capsid. These organisms live within a
host.
Virus Reproduction: There are two main types of viral replication cycles. In the lytic
cycle the virus will attack to a host cell membrane, it often binds to a receptor that the
cell has which gives it access to attach. The virus then injects its DNA/RNA genetic
material into the cell (through deception), some types of viruses are actually taken
inside the cell themselves. Some hosts are tricked into recognising the virus as a food
particle. The host then makes new virus particles using the machinery of the host and
so many new viruses are assembled that it can cause the cell membrane of the host to
rupture and lyse (release mature virus particles). These new viral copies once released
after all resources are used up, go on to infect other host cells. The lysing of the cell
membrane causes the cell to die, as it cannot survive without this vital aspect. This is
called the lytic cycle. Viruses reproduce in a living cell and because they can make
many hundreds of viruses inside each cell before it dies, this causes many more cells to
die or organs to malfunction, which leads to symptoms or illness.
Vaccines:
Used as a means of protection for a wide range of preventable and potentially serious
illnesses.
Vaccines work as they are used to trigger the body’s adaptive immune system and
develop Immunological memory – once the individual is exposed to a particular
pathogen they will develop resistance to infection with the same pathogen in the
future
Our adaptive immune system contains white blood cells known as T and B lymphocytes
– which are activated after the primary exposure to a pathogen. Also known as
memory cells these lymphocytes remain in the individual, ready to react quickly when
the individual is re-exposed to that particular pathogen (secondary exposure). This is
called adaptive immunity.
The immunological memory helps the immune system to respond more rapidly and
effectively than during the primary exposure – as a result the individual is generally
protected from the development of disease symptoms
Vaccines work to generate the immunological memory artificially at an early stage to
prevent future disease. It is comprised of a weakened version of pathogens (live
attenuated vaccines), inactive pathogens or particular parts of pathogens (subunit
vaccine – made from the antigen of a pathogen – the chemical marker which actually
triggers an immune response) into the individual needing of protection. Live
attenuated vaccines are difficult to make and are quite powerful – so those with
weaker immune systems cannot have them, compared to inactive vaccines don’t
create long lasting immunity. These vaccine components activate a specific immune
response mimicking primary infection but weak enough not to cause the development
of disease symptoms. This primary exposure to a pathogen is to create a rapid memory
immune response system for secondary exposure.
Through immunological memory, vaccination prevents and controls the spread of a
wide range of illnesses. All credible scientific evidence strongly supports the
importance of vaccination in avoiding preventable illness in individuals and
populations.
When foreign microbes invade us, the immune system triggers a variety of responses
in an attempt to identify and remove them from our body. The innate immune
responses also trigger our second line of defence called adaptive immunity
- an immunity that occurs after exposure to an antigen either from a pathogen or a
vaccination – created using memory T and B cells.
Carbon Cycle: Carbon is important as it helps build organism’s cells. Building blocks of
matter
Plants use the carbon in the atmospheric CO2 and water to make sugars and other
carbohydrates to grow and reproduce. They do this through the process of
photosynthesis, where they take in carbon from the atmospheric environment and
through a process called carbon fixation – they solidify/convert the carbon into organic
compounds such as sugars. These plants end up being eaten by other organisms
(animals) which supply them with the building blocks for other biological molecules
and fuel. After being metabolised the carbon returns to the environment in one of
several different ways, ending up in the air, water or the earth itself. From here carbon
can be released naturally – through the process of cellular respiration either
anaerobically or aerobically (glucose (+oxygen) -> carbon dioxide + water + energy) –
this can immediately be reversed by photo synthesizers. For organisms that live in
water the carob that they release largely ends up dissolved in that water, and oceans
and other surface water can also dissolve carbon dioxide directly from the air. (Water
and carbon dioxide react to form a carbonic acid). When either plants or animals die,
their remains are digested by decomposers in the soil and water. Decomposers also
respire either aerobically or anaerobically using carbon compounds in dead tissue. In
doing so, decomposers release CO2 into the air so that it can be used once again by
plants. The action of the decomposers in the carbon cycle enables carbon that would
remain locked up in the tissues of dead plants/animals to be released back into the
atmosphere so that plants can turn it into a form that can be used by all other living
organisms. The energy available to ecosystems would not be sufficient to sustain all
the organisms if decomposers were not apart of the carbon cycle. Carbon can also be
extracted artificially by humans (fossil fuels) returning carbon dioxide to the
atmosphere – starting the cycle over again.
Nitrogen cycle: Nitrogen is important as it helps to produce amino acids/proteins
which are needed for growth, repair and replacement of tissues and cells. Atmospheric
nitrogen consists of about 78% of the air – and cannot be used directly by leguminous
plants and animals ,it needs to be converted into nitrogenous compounds beforehand
– which is called nitrogen fixation. Rhizobium bacterium in the root nodules and soil of
leguminous plants (denitrifying bacteria) convert nitrogen into ammonia. Nitrifying
bacteria convert ammonia into nitrites and then into nitrates. Plants take these
nitrates from the soil and use them to make proteins. Animals then eat the nitrogen in
the plants to get proteins. Dead plants/animals and animal waste contain nitrogenous
wastes. Over time through decomposers this waste decays and ammonia is released
through the process of ammonification – which is turned by nitrifying bacteria back
into nitrates. Nitrates can either be used by plants again or converted by denitrifying
bacteria back into atmospheric nitrogen. The percentage of nitrogen in the
atmosphere will remain constant.
Sewage treatment: When chemical and biological waste in sewage is broken down so
that it can be returned to the environment. Sewage treatment reduces the spread of
diseases and prevents the destruction of waterways by raw sewage and reduces the
small. Sewage consists of three main parts – water, debris and bacteria. Sewage
treatment is important as it helps to recycle nutrients and water. A sewage treatment
plant involves primary treatment – where large solids and plant material are removed,
and secondary treatment (aeration tanks and sludge digesters) – where liquid and solid
organic waste is further reduced using microbes.
Aeration Tanks: Liquid organic waste is broken down with the use of aeration tanks.
Aeration tanks are uncovered (to reduce toxic waste build-up of CO2) and oxygen is
pumped into them regularly to provide the aerobic bacteria with enough supplies of
oxygen to feed and respire – removing any harmful organisms and making it safe to be
pumped back into the environment. This means that this is where aerobic bacteria can
survive as it contains a high level of oxygen – which they use to release carbon dioxide,
water and energy in the respiration process. The remaining water is still filled with
pathogenic bacteria so needs further treatment, first air is filtered through the water
promoting the growth of aerobic bacteria, then the water is trickled through stones
where other organisms feed on the bacteria, further sediment tanks capture more
sludge and finally water passes slowly through reed beds where any remaining
pathogens are killed by the oxidising conditions and the water re-joins the river or is
pumped out to sea.
Sludge Digesters: Screens/filters take out large objects that may have fallen into the
sewage system and the sewage flows slowly to allow grit and gravel to settle. The
solids suspended in the water, mostly faeces, settle out in sedimentation tanks and are
pumped into anaerobic sludge digesters – where anaerobic bacteria can live/survive.
Here the bacteria feed on the solid organic waste, breaking it down to produce
nutrients and methane gas – which is burnt to provide electricity to drive the pumps
and the rest of the machinery. The sludge digester is a closed tank, so there is not a
constant supply of oxygen. The methane gas can also be used to keep the tank warm
to ensure the bacterial enzymes are kept at an optimum temperature, as well as a fuel
source. The remaining nutrients (sludge) is dried and can normally be used as a
valuable fertilizer/composts to encourage growth in plants – however if industrial
waste is diverted into the sewage, the sludge may be contaminated by heavy metals
and other pollutants – so must be dumped in a landfill.
Saprophytic bacteria is vital for successful sewage treatment
Discharging untreated sewage can lead to waterborne diseases, oxygen depletion of
water and can cause aquatic life to die when pumped back into the water
Final product of sewage treatment can be used as biofuels (instead of fossil fuels such
as coal and oil).
Food Preservation: Designed to produce an environment free of micro-organisms or an
environment that is unsuitable for their growth and reproduction
Food Poisoning: The ill effect on health caused by the consumption of contaminated
food by bacteria or their toxins.
Bacteria and Fungi can cause spoilage due to:
Extracellular digestion
High population numbers
Toxic waste products
Toxin secretions by Bacteria, Fungi, Parasites or pathogens cause spoilage and
excretion of waste products can cause illness/digestive problems.
Food spoilage is caused by particular secretions from microbes that bring out chemical
changes within the food, these chemical changes render it unfit for human
consumption. Food preservation techniques interrupt these chemical changes – to do
this you must either inhibit microbial growth or simply kill the microbes:
Chemical preservation (acidification/pickling food) – using substance like oil or vinegar
lowers the pH level, causing damage to cell membranes and the denaturation of
enzymes secreted by bacteria (lowers the rate of extracellular digestion – less energy –
lower rate of reproduction) – Arrests the growth of microbes. Sugar is also used as a
popular preservative in jams/spreads as it draws water away – Humectants inhibit
growth.
Dehydration (drying, smoking – fish, salting – fish/meat) – removes moisture, prevents
decay and arrests bacterial growth. Reduces moisture needed to activate enzyme
activity = slow growth
Irradiation – exposing foods to ionizing radiation that damages the DNA of the
microbes meaning that reproduction is no longer able to take place. It doesn’t change
the way that the food looks – e.g. beef, pork, fresh fruits and vegetables, lobster,
shrimp, crab.
Low temperature preservation (refrigeration/freezing) – reduces the moisture present
in the food, slowing down enzyme activity.
Heating (canning, pasteurisation, milking) = the high temperatures denatures enzymes,
meaning no nutrition/energy can be gained and life processes cannot occur.
Antiseptic: Any substance that kills or inhibits the growth of disease producing microorganisms and is in general not toxic to human tissue. E.g. Dettol.
Disinfectant: Any substance that kills or inhibits the growth of disease producing
micro-organisms and is in general toxic to human tissue. E.g. Cleaning products.
Antibiotics: Pathogenic bacteria in the body cause infections which can be treated by
antibiotics. Antibiotics are a type of medication that interrupts the function of bacteria.
Antibiotics disrupt the metabolism of bacterial cells, damage the cells walls (weakening
them/stopping them from forming), stops essential chemicals from forming = damages
cell wall further, stopping an increase in cell size (growth) and damages DNA –
preventing reproduction or repairment of any DNA. Antibiotics can be bacteriostatic
(bacteria stopping) or bactericidal (bacteria killing). Bacteriostatic antibiotics slow the
growth of bacteria by interfering with the processes the bacteria need to multiply –
these processes include DNA replication, metabolism e.g. enzyme activity and protein
production. Bactericidal antibiotics kill the bacteria, for example by preventing the
bacteria from making a cell wall. Antibiotics can be broad-spectrum
(Any antibiotic that is active against a wide range of bacteria). Antibiotics can be
narrow spectrum only affecting one or two types of bacteria. Antibiotics take
advantage of the difference between the structure of the bacterial cell and the host
cell. Fungi secrete a toxin which has an antibiotic affect on bacteria. Antibiotics target
the most susceptible bacteria in a population first. Antibiotics are ineffective on viruses
due to structural differences, as antibiotics are designed to target specific feature of
bacteria only. Viruses incorporate themselves into a host cell in order to multiply,
Bacteriostatic antibiotics that affect bacterial DNA, metabolism or protein production
do not attack body cells and therefore do not slow the growth of viruses. Viruses also
do not have a cell wall, so therefore bactericidal antibiotics that act on cell walls
cannot kill viruses.
Antibiotic resistance: Any bacterial population has variation in susceptibility to
antibiotics, when exposed to an antibiotic, bacteria who are resistant can survive the
action of antibiotics, go on to reproduce and their offspring will have that resistance.
Those who are not resistance will die off. Bacteria become resistant due to a
favourable mutation which gives them an increased chance of survival. In a population
if only some are resistant, antibiotics kill the bacteria causing the illness as well as good
bacteria protecting the body from infection, then the drug-resistant bacteria are now
allowed to grow and take over. These mutations are carried on through reproduction
creating a larger population that is medically unable to be stopped. It is important to
finish a dose of antibiotics because it will increase the chance of killing all bacteria
including the mutants. If the patient does not complete the course, the resistant
bacteria may go on to keep infecting the patient and others. Therefore, if all antibiotics
are taken it reduces the likely hood of bacteria to remain and reduces the chance of
bacteria mutating and becoming resistant.
Fungal Infections: Make us sick by – being present, extra-cellular digestion, toxin. Cures
= anti-fungal creams, diet change (if internal), washing/drying skin, avoid sharing
common moist spaces, cleaning surfaces with disinfectants.
Plant Diseases: Secondary affect if eaten by humans/animals, mostly fungal/virusbased diseases. To treat – burnt he affected areas or remove the fungal infection with
sterilised equipment immediately.
Pathogen: Disease causing micro-organism (agent). E.g. viruses, some bacteria/fungi,
protozoans
Disease: An abnormality of the body, a condition in which the normal function of some
part of the body (cells, tissues or organs) is disturbed. Many diseases are caused by
pathogens, as they produce harmful toxins that cause damage to the body, causing
pain, discomfort or even death.
Preventing infection: There are a few main lines of defence that work to prevent
infection/disease
1. Natural barriers – skin, scabs, acids in the stomach, sticky mucus secretions,
tears, wax, saliva, along with fine hairs.
2. Immune system: White blood cells called PHAGOCYTES – ingest/engulf
pathogens and kill them if they get past the natural barriers, they are nonspecific and will target any foreign object/microbes that enter the body. They
trigger inflammation (swelling and redness) in order to increase blood flow to
the area. The incoming blood brings more blood flow to the area increase
phagocyte number and removes toxins. LYMPHOCYTES – White blood cell that
is target specific, produce antibodies for antigens and remembers the ‘recipe’
for producing antigens.
Antigens: Unique chemical markers on the surface on pathogens, the body regards
them as foreign, so they trigger an immune response (inflammation/number of
phagocytes/lymphocytes).
Antibodies: A protein produced by white blood cells (Lymphocytes) in response to the
entry of a foreign substance into the body. White blood cells can stick to the it’s microorganism if it has the right antibody to match the antigen (lock and key). Only a specific
antibody can fit a specific antigen. Once the body has made an antibody in recognition
of a pathogen, memory T and B cells can remember to make that antibody again.
When this happens, the microbe can be killed or clumped together to make It easier
for other white blood cells to kill them.
Toxins: A poison produced by bacteria/fungi. Bacteria excrete toxins which cause the
body’s cells to become inflamed and start to malfunction. As the bacteria reproduce
and increase in numbers, the amount of toxin they excrete increases. Bacterial
reproduction doesn’t destroy living cells but instead increases the amount of toxins
excreted. It is the toxins which then cause the inflammation in parts of the body.
Toxins released by bacteria cause the disease.
1.5 Mammals as consumers:
Mammals: Feed their young milk, are vertebrates, have fur or hair, are able to regulate
their body temperature and/or are warm-blooded. Mammals are consumers, they
ingest food to gain nutrients and energy to carry out life processes. Food is digested
(broken down) into smaller nutrients that can be easily absorbed from the digestive
system into the bloodstream. Mammals can be classified based on their diet.
Herbivores – those that eat mainly plant material
Carnivores – those that eat mainly animal material
Omnivores – those that eat a mixture of plant and animal material
Movement – being able to move their parts
Respiration – turning organic matter and oxygen into energy
Sensitivity – responding to the outside world
Cells – form the basic building blocks of their body
Growth – reaching full size, repairing old cells
Reproduction – producing offspring
Excretion – the removal of waste products from the body
Nutrition – getting organic matter (food) when needed
Carbohydrates: Come from plants and in the form of sugars, known as ‘energy’ foods
and are divided into two sub-groups based on the kind of sugar it is created from:
- Complex sugars: Many sugar molecules chemically bonded together, e.g.
starch. Found in plants such as potato, kumara, bananas, seeds and grains. It is
-
digested slowly meaning that it releases energy slowly – so it an ideal source of
energy for endurance athletes.
Simple Sugars: Made of one or two sugar molecules (not chemically bonded),
E.g. glucose, sucrose, fructose. Provides us with energy to move, grow and keep
warm. Easily digested and enters the bloodstream quickly, giving us almost
instant energy. Glucose = lollies/sports drinks, Sucrose = table sugar and
fructose = fruit.
Proteins: They form the main structural part of animals cells, therefore foods high in
protein usually originate from animal tissue. E.g. meat, eggs, dairy products and some
plant-based foods are also high in protein (seeds). Required for growth, repairing
damaged tissue, controlling chemical reactions (enzymes), sending messages around
the body (hormones) and providing an emergency energy source. Made of amino acids
- structures vary per different protein.
Lipids (Fats/Triglycerides): Oils and fats – generally solid lipids come from animal
sources and liquid lipids come from plant sources. Required for making cell
membranes (outer part of the cell), insulation (keeping us warm) and protecting
organs (e.g. kidneys). Too much can be bad for you and can lead to a range of health
problems, such as obesity and heart disease. Made from glycerol and fatty acids.
Food Test (Complex Sugars - Starch): THE IODINE TEST – The Iodine solution, by itself,
appears yellow in low concentration and brown in high concentrations.
- NO COMPLEX SUGARS PRESENT  SOLUTION DOES NOT CHANGE COLOUR
- COMPLEX SUGARS PRESENT  SOLUTION APPEARS BLUE/BLACK
Food Test (Simple Sugars - Glucose): THE BENEDICTS TEST – The Benedict’s solution in
nature is Blue
- NO SIMPLE SUGARS PRESENT  SOLUTION DOES NOT CHANGE COLOUR
- SIMPLE SUGARS PRESENT  SOLUTION APPEARS RED/ORANGE
Food Test (Proteins): THE BIURET TEST – The sodium hydroxide/copper sulphate is Blue
in nature
- NO PROTEINS PRESENT  SOLUTION DOES NOT CHANGE COLOUR
- PROTEINS PRESENT  SOLUTION APPEARS PURPLE
Food Test (Lipids/Fats): THE PAPER TOWEL TEST – The paper towel is opaque in nature
- NO LIPIDS ARE PRESENT  THE PAPER TOWEL WILL REMAIN OPAQUE
- LIPIDS ARE PRESENT  THE PAPER TOWEL WILL BECOME TRANSPARENT
Digestion Process: The process of breaking down large biological macromolecules into
smaller soluble molecules that can be absorbed into the circulatory system for use
throughout the body. Also known as the digestive system it comprises of five different
stages:
Ingestion  Digestion  Absorption  Assimilation  Egestion
Ingestion: The process of absorbing nutrients into the body by eating or drinking them.
Digestion: The process in which food is broken down mechanically by teeth and
chemically by the action of gastric juices and enzymes (chemical digestion)
Physical Digestion: Occurs when food is broken down into smaller pieces by the teeth
or muscle action of the stomach (peristalsis). This is necessary for efficient and
effective digestion as it increases the surface area available for enzymes to act upon,
without making any chemical changes. Also known as Mammalian dentition and
mastication (scientific term for chewing).
Chemical Digestion: Similar to physical digestion, as it results in food being broken
down into smaller pieces but is different in that it involves the use of enzymes, e.g.
amylase in the mouth. These break down the chemical bonds holding the food
molecules together so they are small enough for absorption.
Molars: Numerous, large, flat-surfaced, found towards the rear of the jaw. They are
used for crushing and grinding plant material. They are the dominant teeth found in
herbivores.
Canines: Pointed teeth (eye teeth). Found towards the front side of the jaw. Used for
ripping/treating flesh off the bone and holding onto/piercing the vital organs of prey.
Incisors: Chisel-like teeth found at the front of the jaw. They are used for cutting and
removing food from its source (E.g. grass from the ground or meat from the bone).
Herbivore Skull: Herbivores have teeth adapted to eating tough plant material (grass).
Plants are difficult to digest because their cells are covered in a tough cellulose cell
wall. The digestion begins in the mouth, herbivores produce a lot of saliva – where the
enzyme amylase starts to moisten/break down the vegetation. Herbivores tend to
chew their food more, as to break down the cellulose (tough fibres) the chewing
exposes the plant cells to subsequent enzymes to act upon. At the front of the jaw
they have incisors – used for cutting plants at their source. The upper jaw has a bony
cropping pad that the lower incisors cut into (allowing them to chop grass very slowly).
They have a large diastema (gap) that allows the tongue to manipulate food (roll it into
a ball) and keep the freshly eaten grass separate from the cud (regurgitated material).
They often have large tongues to do so. They have a thick ‘heavy’ jaw and large jaw
muscles to grind and chew. They also have large flat molars for grinding – where the
molars slide over each other. Don’t often have canines, but some herbivores have
them for defence/attracting a mate (not for eating).
Carnivore Skull: Carnivores have teeth specially adapted for eating meat/flesh/animal
material. These protein and lipid-rich foods are easier to digest than tough cellulose
plant material and since carnivores don’t produce enzymes in their saliva, there is no
need to extensively chew food prior to swallowing. At the front of the upper and lower
jaw are the incisor teeth which assist in ripping/cutting meat off the bone. They
generally don’t have crushing molars, instead they have smaller pointed molars called
carnassials, which cut against each other like the blades of scissors. This cutting action
enables carnivores to shear through bone and slice digestible sized chunks of flesh
from a carcase. Carnivores also have large pointed canines to assist in ripping/tearing
flesh off the bone and/or piercing vital organs in their living prey. Carnivores are also
equipped with a wide mouth opening in relation to their head size, providing an
advantage when seizing, killing, carrying and dismembering prey.
Enzymes: A substance produced by a living organism which acts as a catalyst to bring
about a specific biochemical reaction. Enzymes help split food particles into smaller
particles that can be easily absorbed into the bloodstream – without them the body
would fail to gain vital nutrients quickly. Enzymes are not used up in reactions, instead
they can be used again and again. Each enzyme has a specific shape (active site) into
which only a specific substrate (what is being broken down) fits. Each enzyme works
best at an optimum temperature and pH level. Enzymes are described as catalyst
because they lower the minimum activation energy required for a reaction, hence
speeding up the rate of reaction (remain unchanged at the end). Enzymes work in
conjunction with substrates – enzymes and substrates are always moving and
occasionally they collide with the correct speed and orientation, so that the substrate
fits with the active site. Collision theory, which is used to predict the rate of chemical
reactions, dictates that a collision must occur with sufficient energy and the correct
orientation. Once this occurs digestion can begin:
1. A substrate is drawn into the active site of an enzyme
2. The substrate shape must be compatible with the enzyme active site in order to
fit and be reacted upon
3. If the minimum activation energy, speed and correct orientation requirement is
met, the enzyme and substrate bind using a lock and key mechanism
4. The enzyme will then modify the substrate, in some instances the substrate is
broken down, releasing two or more products.
Effect of temperature on enzymes: Enzymes work best at optimum temperatures and
the rate of reaction increase as the temperature increase (more kinetic energy – more
successful collisions with regards to collision theory). However, too high a temperature
can cause enzyme denaturation - disrupting the active site meaning that reactions are
no longer able to occur.
Effect of pH level on enzymes: Enzymes work best at an optimum pH level. However,
too high (acidic) or too low (basic/alkaline) a pH level can cause enzyme denaturation.
Enzyme Denaturation: Each enzyme has conditions under which it functions best, in
other words the point at which the rate of reaction is the highest. Among these
condition the most well-known are temperature and pH, if these aspects vary from the
optimal level for the enzyme – it can become denatured and consequently the rate of
reaction will decrease. One consequence of denaturation can be the disturbance of the
organisms inner systemic balance, also called homeostasis. For example, the activity of
protease which is not optimal can affect protein digestion in the body. The
denaturation of enzymes mean that the shape has changed in some way, which is
usually permanent. The activity of an enzyme depends heavily on its shape, particularly
with the active site which binds with substrate(s). The change of the structure means
that the active site is not shaped for optimal rate of reaction. Denaturation occurs
when the protein from which the enzyme is made from denatures. To understand this
biologically, when the temperature increases the individual amino acids that make up
the enzyme vibrate at a higher frequency. This results in the breaking of hydrogen
bonds between amino acids and different parts of the protein chain, leading to a
change of shape. A pH level that is too high or low for a particular enzyme can lead to a
change of protein structure. If the pH is too low, then the concentration of hydrogen
ions will be greater than normal and these will interact with amino acids to change to
shape of the active site.
Enzyme Amylase: Converts – CARBOHYDRATES  SIMPLE SUGARS, produced in the
salivary glands, pancreas and small intestine. Works at an optimum pH level of 7 but is
able to function within the pH range of 4-10.
Enzyme Lipase: Converts – LIPIDS & FATS  FATTY ACIDS/GLYCEROL, produced in the
pancreas and the small intestine. Works at an optimum pH level of 6 but is able to
function within the pH range of 5-11.
Enzyme Protease: Converts – PROTEINS  AMINO ACIDS, produced in the stomach,
pancreas and the small intestine. Works at an optimum pH level of 2 but is able to
function within the pH range of 0.5-8.
Digestion begins in the mouth: Chewing (mastication) causes glands in the mouth to
secrete a watery liquid called saliva. Saliva moistens, softens and lubricates food
making it easier to chew and swallow. Saliva contains the enzyme amylase which
begins the digestion of starch into smaller simple sugars. Mastication also increase the
surface area of food which helps to accelerate the breakdown of carbohydrate
molecules. STARCH  MALTOSE  GLUCOSE. Food is then rolled into a bolus (ball)
and swallowed to pass into the oesophagus. The epiglottis is a section that prevents
the bolus from passing into the airway in the lungs. The bolus moves down the
oesophagus in a wave-like motion called peristalsis. Peristalsis moves the food through
the digestive system and aids the mechanical digestion of the food and helps mix it
with gastric juices and enzymes. Circular muscles contract behind the bolus pushing it
downwards and longitudinal muscles contract, widening the diameter and shortening
the length of the tube. This motion continues until the food reaches the next organ
(stomach) or is excreted. Oesophagus has a neutral pH (7)
Stomach: The oesophagus leads to the stomach which is a large elastic bag that
contracts to mix food and gastric juices secreted by glands in the stomach wall. The
stomach can expand to hold many litres of food (2-4L), so a meal can be ingested
quickly and then digested slowly over time. Carbohydrates have already begun to be
turned into simple sugars by amylase. Other nutrients remain undigested. The interior
of the stomach is lined with holes called gastric pits. Cells within these pits secrete
three types of fluids – caused gastric fluid. Hydrochloric acid (HCl) – corrosive strong
acid (pH 1-2) that causes proteins to denature, unravelling them and exposing the
bonds holding the molecules together. This exposure allows digestive enzymes to
break long chains of amino acids into individual molecules. The acidic nature also kills
many pathogens that enter the body via food. Pepsin – enzyme that catalyses the
breakdown of protein into amino acids. Mucus – secreted to forma a protective layer
of the stomach that prevents acid and enzymes from digesting the stomach itself.
ACIDIC pH (1-2)
Small Intestine: A long tube 6-7m long. Chyme exits the stomach and passes into the
duodenum (first section of the small intestine). Chyme enters the duodenum at
intervals and gets mixed with fluids from the gall bladder and pancreas (bile and
pancreatic juices). Duodenum is linked to the gall bladder (bile) and pancreas
(enzymes). Digestion of lipids, carbs and proteins. Muscular movements mix food with
bile and enzymes enable rapid food digestion. Duodenum pH (6), Ileum pH (7)
Bile: Made in the liver and stored in the gall bladder. It passes from the gall bladder
through the bile duct to enter the duodenum. Bile is an alkaline solution so it
neutralises the acidic chyme and the gastric juices coming from the stomach. It also
breaks down fat into fat droplets (emulsification of fat). This increases the surface area
of fat exposed to the action of the enzyme lipase = a faster reaction rate.
Pancreatic Juices: Released into the duodenum from the pancreas along the pancreatic
duct. Contains enzymes that assist in digestion – including Amylase (Ideal pH 7-8),
Lipase (Ideal pH 7-8) and Protease (pH 2-3).
Absorption: Digested food molecules are absorbed through the intestinal wall and
then is carried by the bloodstream to be used by the cells of the body. Waste products
and fibre remain in the system.
Ileum: Middle section of the small intestine of mammals. Covered in millions of tiny
finger-like projections called villi. Surface of the villi are covered with smaller
projections called microvilli. Villi and microvilli work to increase the surface area of the
intestine which increases the rate of absorption. Each villi is surrounded by a network
of blood capillaries AND a central lacteal ‘fat duct’. Digested carbohydrates (glucose)
and proteins (amino acids) enter the blood capillaries directly for transport to the liver
via the hepatic portal vein. Fatty acids and glycerol also enter the lacteal ‘fat’ duct
where they recombine to form fat droplets and then pass through the lymph system
before entering the blood. Digested food molecules move through the membrane of
the small intestine by either passive diffusion and/or active transport. Passive diffusion
– the movement of molecules from an area of high concentration to an area of low
concentration (no energy required to do so). Active Transport – the movement of
molecules which requires energy.
Muscular Walls: Helps move the food along by the process of peristalsis. It also churns
the chyme over, ensuring its exposure to the villi/microvilli.
Villi/Microvilli: Increase the surface area, increasing the rate of nutrient absorption
Capillary (blood vessel) network: Thin walled capillary ensures that digested molecules
go directly to the bloodstream so the nutrients can be used quickly and efficiently.
Thin walls of the Villi: Ensures the rapid absorption of nutrients into the blood, as the
nutrients are absorbed quickly because they only have to diffuse through a layer once
cell thick – reduces the distance between the villi/microvilli and the capillaries/fat duct
– SHORT DIFFUSION DISTANCE
Lymph Capillary (inside villi): Absorbs fatty acids into the lymph system and also draws
excess tissue fluid to be filtered and returned back to the blood.
Lymphatic system: Network of tissues/organs that help rid the body of toxins, waste
and other unwanted materials, as well as transporting lymph (fluid containing WBC)
around the body.
After food has been digested/absorbed from the villi in the small intestine, the
nutrients are absorbed and transported to the LIVER, via the hepatic portal vein. This is
where the process of assimilation occurs.
Assimilation: When absorbed nutrients and products of digestion are then converted
into the fluid or solid substances of the body (cells and tissues). This process occurs in
the liver.
Glucose and amino acids are absorbed into the blood in the capillary network in the
villi and then transported in the blood plasma to the body cells.
Glucose: Some of the glucose arriving via the hepatic portal vein is transported from
the liver to the muscles of the body (from blood to muscle cell). Excessive glucose
(arriving) is stored as glycogen – where it is stored until needed – When the muscles of
the body require more energy the liver can convert glycogen back into glucose to be
transported to the working muscle cells via the circulatory system. Used for respiration
(both anaerobic and aerobic).
Amino Acids: The liver regulates the level of amino acids in the blood that are needed
for protein synthesis. However, amino acids cannot be stored. They are used to make
proteins – for growth, repair and replacement. Excess amino acids are toxic, so they go
through the process of deamination and are converted into glucose (and used for
energy). However, ammonia is a toxic by product of deamination and must be
converted into urea and removed from the body via the excretory system.
Fatty Acids/Glycerol: Absorbed into the lacteal in the villi and transported to cells via
the lymphatic system. They are converted into energy. The liver is able to convert
excess carbohydrates and proteins into fatty acids and triglycerides, which are then
exported and stored in the body as fat. This stored fat is able to be converted into
energy at a later date if required. Fatty acids and glycerol are also released into the
blood as an energy source.
All that remains of a meal is indigestible matter, mucus, dead cells, bacteria, some ions
and water.
The large intestine (colon): Larger diameter than the small intestine. Main function is
the reabsorption of ions and water. The inner surfaces of the colon do not contain villi;
however, the surfaces area is increased by the number of folds in the inner lining. The
water being reabsorbed comes not only from ingestion but also from various secreted
fluids (gastric, pancreatic, bile, etc) also. After this absorption, what remains is referred
to as faeces. This is transported to the rectum (an elastic sac) where it is stored until it
is egested via the anus. SLIGHTLY ACIDIC pH (5-6)
Caecum: A large pouch (found in herbivores), found in humans where the appendix is.
Contains microbes that produce the enzyme cellulase needed for breaking down
cellulose in grass and other plant material. Estimated pH of (6)
Carnivore Digestive system:
- Diet rich in easily digestible protein (limited carbohydrates/no starch)
- Flesh chewed quickly and swallowed
- Shorter and wider overall gut (compared to herbivores)
- Saliva doesn’t contain enzymes, no need for amylase (no starch in diet)
- Peristalsis moves the food along the digestive tract
- Stomach 1 division – most digestion occurs there
- Food spends a longer time period in the stomach (4-6hrs) to allow for digestion
of a larger amount of protein (by the enzymes pepsin and protease – in the
stomach)
- Acidic stomach with low pH level (kills microbes/breaks down food – for
pepsin/protease)
- Food spends a shorter time in the small intestine – amino acids/lipids are easy
to absorb
- Shorter small intestine – diet consists of nutrients that are easily absorbable
- Shorter large intestine – little undigested material/absorption
- Small caecum – no need to have fermenting bacteria
Herbivore Digestive system: (Two main types)
1. Hindgut digestive system (rodents and mice)
2. Foregut digestive system (ruminants – cows, sheep, goats)
Herbivore – Hindgut:
- Food is stored in the stomach for a few hours (plant matter bulky/consumed in
large amounts)
- Large well-developed caecum – contains micro-organisms that produce
cellulase to break down tough cellulose material.
- Longer small intestine – for digestion of large quantities of starch/carbs and
then to absorb glucose (carbohydrates are more difficult to digest)
- Longer small intestine – large amounts of undigested material from their plant
diet, requires more packing/water removal
Herbivore – Foregut:
- Have a bony upper plate in jaw and lower incisors to rip grass
- Food is stored in a large complex stomach (rumen) – with 4 chambers. The first
chamber is slightly acidic (pH 6)  Last chamber is strongly acidic for protein
digestion (pH 2-4)
- Food gets regurgitated in the mouth to be chewed a second time. This is known
as ruminating or chewing the cud. This helps to break down tough cellulose and
increases the production of saliva (as well as the enzyme amylase)
- Produce a lot of saliva which also gets swallowed into the rumen and acts to
stop the liquid in the rumen from becoming too acidic (killing the
microbes/damaging the enzymes).
-
Chemical digestion begins in the stomach as a result of fermentation
Fermentation occurs by the action of bacteria that inhibit the stomach
Fermentation is anaerobic (occurs in the absence of oxygen)
Microbes release an enzyme called cellulase which digests cellulose into
glucose
Carbon dioxide and methane gas are released in large amounts (burping/gas
excretion)
Large well-developed caecum – contains cellulase which assists in breaking
down cellulose
Longer/thinner small intestine – for digestion of large quantities of starch 
glucose
Longer/thinner large intestine – for large amounts of undigested material from
their plant diet which requires more packing/water removal.
Foregut digestive system is more efficient than hindgut digestive systems. As the
bacteria that produces cellulase to break down cellulose is located in the stomach
(rumen) – Foregut, as opposed to later in the caecum (for hindgut). So, digestion
occurs earlier and therefore is more efficient.
Digestive system – an organ system that breaks down food into smaller soluble
molecules so that the food can be absorbed into the body.
Circulatory system – an organ system that transports materials in the blood such as
glucose, amino acids, minerals, oxygen to every cell in the body and removes waste
such as carbon dioxide. This system includes the heart, arteries, veins, etc. Mammalian
– blood, vessels to carry blood, heart.
Gas exchange system – an organ system that transports air into the body so oxygen
can be absorbed into the circulatory system, and carbon dioxide removed as waste.
(Lungs). All three systems are closely linked to one another.
Red Blood cells – carry oxygen around the body. They have a large surface area
Platelets – assist in defence, they help the blood clot and form a scab
White Blood cells – kill invading microbes by producing antibodies
Haemoglobin – protein responsible for carrying oxygen in the blood
These three are all carried around by PLASMA (a yellow-coloured liquid) that assists in
the transportation of CO2 and glucose, as well as taking away waste products to the
kidneys.
Arteries: Carry high pressure oxygenated blood away from the heart (expect the
pulmonary). They have thick walls/layers of muscle (elastic). No valves. High in O2, Low
in CO2, high in nutrients.
Capillaries: They have thin walls (one cell thick)to allow glucose, oxygen, nutrients and
hormones to pass through (via diffusion). Used to connect the arteries and veins.
Veins: Carry low pressure de-oxygenated blood back to the heart (except the
pulmonary). They have thinner, less elastic walls and have valves to prevent the
backflow of blood. High in CO2, low in O2, low in nutrients. Hepatic portal vein – High
in O2, High in CO2, high in nutrients.
The movement of these blood molecules in capillaries into and out of a cell occurs via
diffusion.
Human heart: (consists of two circuits)
1. Pulmonary circuit – carries de-oxygenated blood from the heart to the lungs,
where it is re-oxygenated and sent back to the heart. RIGHT SIDE
2. Systemic circuit – carries oxygenated blood to all of the body’s cells via the
arteries and de-oxygenated blood back to the heart via the veins. LEFT SIDE
- Consists of two sides, a pump made of muscle.
Parts of the heart include:
- Superior/Inferior Vena Cava: Brings de-oxygenated blood from the body into
the heart
- Right Atrium: Receives de-oxygenated blood
- Right Ventricle: Pumps blood to the lungs via the pulmonary artery
- Right/Left Pulmonary artery: Delivers de-oxygenated blood to the lungs from
the heart
- Pulmonary veins: delivers re-oxygenated blood from the lungs back to the heart
- Left Atrium receives oxygenated blood from the lungs
- Left Ventricle: Thickest muscular walls, pumps oxygenated blood to the body
via the aorta
- Septum: Wall that divides the left and right sides of the heart. s
Travel of Blood:
1. Deoxygenated blood (body) enters the superior/inferior vena cava and into the
right atrium
2. Here the blood flows into the right ventricle
3. Then it’s pumped through a valve up to the lungs through the pulmonary circuit
4. Oxygenated blood enters through the pulmonary veins into the left atrium
5. Then it’s pumped through a valve into the left ventricle
6. The left ventricle contracts sending oxygenated blood out the aorta to the rest
of the body
Inferior/superior vena cava  Right atrium  Right ventricle Pulmonary artery 
Lungs  Pulmonary vein  Left Atrium  Right Ventricle  Aorta.
Respiration/Circulatory Link (systems):
- After digestion, glucose is transported to the liver where it is converted into
glycogen for storage. Glucose is released form the liver into the circulation
system to maintain steady concentrations in the blood. The glucose travels to
the capillaries in the organs and tissues of the body where it is absorbed by the
cells and used in respiration. Respiration is the breaking down of glucose with
the help of oxygen to produce carbon dioxide, water and energy.
Aerobic Cellular respiration: Glucose + Oxygen  Water + Carbon Dioxide + lots of ATP
energy
- Glucose: Absorbed into the villi/capillaries from the small intestine and is taken
into the liver via the hepatic portal vein where it is absorbed into the
bloodstream, pumped by the heart to the lungs (to oxygenate the blood) and
taken back to the heart where it is pumped to the cells to be used in
respiration.
- Oxygen: From breathing (inhalation) into the lungs, it is absorbed into the
bloodstream and pumped around the body to be used by the cells. (Lungs for
inhalation).
- Water: The hydrogen from the coenzymes meets the oxygen that the call has
taken in, to form water. It is a by-product of a metabolism reaction.
- Carbon Dioxide: Absorbed from the bloodstream and taken to the lungs to be
exhaled out
- Energy: Lots created, used to carry out life processes.
Anaerobic cellular respiration: Glucose  lactic acid + little ATP energy
- Occurs in the absence of oxygen
- Generates little energy
- Produces lactic acid (toxic to cells) causing muscle fatigue and cramps
- Lactic acid is produced as it is a combination of both carbon, hydrogen and
water
Respiration: the chemical process of combining oxygen with glucose to release energy
Breathing: the physical process of getting oxygen into the bloodstream
The gas exchange system works together with the circulatory system to provide
oxygen for aerobic respiration and to remove the waste of carbon dioxide produced
during respiration.
The lungs contain air sacs called alveoli. Oxygen in the inhaled air diffuses from the
alveoli into the capillaries of the circulatory system while at the same time carbon
dioxide diffuses from the capillaries into the air sacs to be removed in the inhaled air.
At the end of each bronchiole are the tiny air sacs called alveoli and they increase the
surface area (to increase the rate of diffusion of oxygen) and speed up the absorption
of oxygen.
Mouth/Nose  Trachea  Bronchi  Alveoli  Bloodstream