BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
BIOL0601 Module 5 Assignment 5 (M5A)
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
Introduction
BIOL0601 Provincial Biology
Assignment 5
Instructions:
Type your name in the header On Page 2. (First select “Header and Footer” in
Word’s “View” menu or double click in the header area..)
For each answer, at least one dark blue blank line has been provided. Double-click on the line and start typing your answer. It will automatically appear in a distinctive style.
When several blank lines are provided for an answer, clean up by deleting the extra lines after you have typed your answer.
For the long answer questions, insert your answer below each question.
Sometime you will be asked to perform a lab exercise before you have finished your text work.
Only submit your work to your tutor when all the work in the assignment has been completed. If sending your file to your tutor as an email attachment, ensure that it has a file name that includes the course number, assignment number and your name. e.g. BIOL0601_A2_Chiu.doc (with your name in place of “Chiu.”)
Topic
Diagrams
Terms and Definitions
Short Answer Questions
Long Answer Questions
Lab 5A
Lab 5B
Total marks
Marks
8
12
35
25
10
10
/100 /100
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
Diagrams
1. Place the name of the described structure in the space beside the description. Label the diagram below using the letter associated with each structure. ( 8 marks) description name
A this structure stores the fluid which serves as an emulsifying agent in the digestion of fat. gall bladder
B this organ secretes the two hormones involved in the control of blood glucose levels. pancreas
C produces the enzyme amylase which begins the digestion of starch. salivary glands
D the largest organ in the body, it processes nutrients and detoxifies the blood. liver
E this structure is a temporary storage area for solid waste. rectum
F this is a vestigial structure. appendix
G most of the digestion of food and the absorption of nutrients takes place here. small intestine
H this structure is responsible for reclaiming water for the body. large intestine
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A
B
C
D
BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
2.
With reference to the diagram above, fill in the chart with the name of the structure and its function. (4 marks) name of structure the blind spot the lens the fovea sclera function this is the place where the nerves exit the eye to form the optic nerve; there are no light receptors at this spot giving rise to the name blind spot the lens is responsible for focusing the light on the retina to form a sharp image this is the area of greatest visual acuity because the concentration of cones (colour receptors) is highest here tough, white outer layer of the eyeball
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
Terms (12 marks)
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
Short Answer Questions
1. The pancreas is both an endocrine and an exocrine gland. Discuss using specific examples to illustrate your answer. (4 marks)
An endocrine gland secretes chemical messengers (hormones) into the blood stream that have an action on a distant organ. In the case of the pancreas, the hormone insulin is a good example. It is produced in the Islets of Langerhans in the pancreas and is secreted into the blood stream. It has the action of enabling the transport of glucose across the cell membrane.
An exocrine gland excretes its products directly through an epithelial surface or through ducts. The digestive enzymes produced by the pancreas are good examples. The pancreas produces amylases, lipases, proteases and nucleases. These are excreted into the pancreatic duct and carried to the small intestine where they have their action. The pancreas also produces an alkaline secretion containing bicarbonate ions to modify the pH of the small intestine.
2. When the lights are turned off, it takes a while before you are able see, and about twenty minutes until night vision is fully functional, and for sharpest night vision, one looks sideways. How do the properties of the cornea and rods and the cones relate to this? (5 marks)
The retina is made up of two types of sensors – rods and cones. The cones are the colour receptors and are responsible for daytime vision. The concentration of cones is not uniform. They are in highest concentration at the focal point of the eye, the fovea. They allow us to see colour and fine detail in full light. The rods are the non-colour nighttime receptors. Because they are for use primarily at night, they are very sensitive to light. In fact, in bright light they are bleached and non-functional.
They are not uniformly distributed either. There are few of them in and around the fovea. They are more concentrated toward the periphery of the retina.
When one goes from light into darkness, vision is limited at first. This is because it takes a while for the rods to recover from being bleached. Once recovered, full night vision is in effect. In the dark one will also try to focus the image on the side of the eye by looking sideways at an object. This is to bring the image into focus on an area of the retina that has the highest concentration of rods in an attempt to see the object more clearly in darkness.
3. Compare and contrast the sympathetic and parasympathetic nervous systems. (5 marks)
The sympathetic and parasympathetic nervous system are parts of the autonomic nervous system.
They are responsible for regulating the activity of cardiac, smooth muscles, organs and glands. One system, the sympathetic nervous system, is responsible for gear the body up for survival (the fight or flight response), and the parasympathetic nervous system is responsible for operations during non-stressful times.
The sympathetic nervous system operates during times of stress. The neurotransmitter involved is norepinephrine (similar to adrenalin). It cases the heart rate to rise, dilates the bronchii, and causes the release of glucose into the blood stream. The sympathetic nervous system also inhibits the digestive system, kidneys – the activities that are not necessary when you are in a fight or flight situation.
The parasympathetic nervous system works in opposition to the sympathetic nervous system through the neurotransmitter acetylcholine. It controls those activities associated with a relaxed state, particularly the situation after a meal. It slows the heart rate, promotes activity of the digestive system and generally calms the body. It is also called the rest and digest system or the housekeeper system.
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
4. Describe the difference between the composition of the blood and the urine, and how the kidney accomplishes this. (6 marks)
The kidneys are important for the excretion of metabolic wastes and for maintaining the water-salt balance of the body.
The kidneys work by filtering the blood. In fact, a large portion of the blood passes out as filtrate.
Materials in solution (water, nitrogenous wastes, nutrient, salts, soluble materials like hormones) pass out with the filtrate. Formed elements and plasma proteins remain in the blood. The rest of the kidney is designed to recover nutrients, and control the levels of salts and the pH of the blood.
Tubular reabsorption is responsible for reclaiming the necessary components. Materials like nitrogenous wastes and excess salts are not reabsorbed, but most of the water, nutrient and some salts are actively reabsorbed into the peritubular capillaries. About 65% of sodium ions, and nutrients such as glucose and amino acids are reabsorbed in the proximal convoluted tubule. Water is reabsorbed osmotically into the blood. Tubular secretion is also important. Substances such as hydrogen ions, creatine, and some drugs are actively secreted
The loop of the nephron is important for the regulation of the tonicity of the urine. It is in the loop portion that the concentration of the urine is adjusted according the needs of the body. Under a shortage of water, concentrated urine is produced, and a more dilute urine is produced when water is not in short supply.
5. Describe the components of a reflex arc (spinal reflex). What is the importance of a reflex arc to an organism?
(4 marks)
A reflex arc is called a spinal reflex because it involves a sensor, the spinal chord and an effector – not the central nervous system. It is designed to avoid the central nervous system for fast response in order to minimize damage to the organism.
Taking the knee jerk as an example, the receptor is the stretch receptor in the tendon that traverses the knee. When taped sharply, the receptor will fire and send an impulse along the sensory neuron to the dorsal horn of the spinal chord. Here it synapses with an interneuron, which lies totally within the spinal chord. The interneuron transmits the message to a motor neuron. The motor neuron carries an impulse to the muscle, causing it to contract rapidly. This whole process takes very little time compared to the time required if the impulse had to travel up to the brain and then back down again.
6. Describe how a nerve impulse is transmitted along a nerve fibre and explain how myelin is involved in the process. (6 marks)
The neuron has a resting potential derived from the differential distribution of ions on the inside and the outside of the membrane. The inside of the membrane has a negative charge and the outside has a positive charge. When a stimulus is applied to the membrane, sodium gates in the membrane open and sodium ions begin to move to the interior. This phase is called depolarization.
When the depolarization is complete, potassium ions are pumped to the outside of the axon. This re-establishes the charge distribution and is called repolarization. When this is complete, the resting potential has been re-established. The sodium/potassium pump exchanges ions to re-establish the resting condition of the axon with sodium ions on the outside and potassium ions on the inside.
Normally the action potential propagates in a linear fashion along an axon. A depolarization of the membrane acts as a stimulus for the depolarization of the adjacent membrane, thus the action potential rolls along the axon. If the axon is myelinated there are areas where the axon is not covered by myelin. These are called nodes of Ranvier. These nodes are placed at regular intervals along the axon. An action potential at one node casues an action potential at an adjacent node. In this way the action potential “skip” from node to node and results in much faster conduction of the nerve impulse.
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
Long Answer Questions
Answer the following questions on a separate piece of paper. Each of your answers should be two to three paragraphs long. Use your own wording.
1. Explain how insulin and glucagon maintain blood glucose levels. (4 marks)
Insulin is secreted by the Islet cells of the pancreas in response to high blood glucose levels. Insulin causes the uptake of glucose by cells, lowering the blood glucose level.
Glucagon is produced by the Islet cells and is secreted when blood glucose levels fall too low. It targets primarily the liver, causing it to convert its store of glycogen into glucose. It also promotes the break down of fat into glycerol and fatty acids which the liver can convert to glucose. Both of these produce an increase in the blood glucose levels.
2. This diagram illustrates the mechanism that controls the level of thyroxin in the body. Boxes on the left hand side identify a hormone. Boxes on the right identify the feedback mechanism and target organ.
Fill in the boxes so as to describe the homeostatic mechanism that controls the level of thyroxine in circulation.
(10 marks) a) In response to high levels of thyroxine in the blood, the hypothalamus is inhibited from producing thyroid releasing hormone .
Low levels of thyroxine have the reverse effect b) In response to high levels of thyroxine in the blood, the pituitary is inhibited from producing thyroid stimulating hormone.
Low levels of thyroxine have the reverse effect c) The hypothalamus produces thyroid releasing hormone which causes the pituitary to produce thyroid stimulating hormone. d) The pituitary produces thyroid stimulating hormone which causes the thyroid to produce thyroxine.
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
3. Imagine that you are eating a roast beef sandwich (it contains protein, carbohydrate and lipids).
Follow the food through the digestive system, and describe what is happening to it as it passes through each of the sections. Be sure to include both chemical and mechanical events, and the accessory organs that are involved. (12 marks)
Mouth mechanical chewing to mechanically break the food into smaller pieces
Saliva is secreted to lubricate chemical
The tongue rolls the food into a bolus for swallowing salivary amylase begins the breakdown of starch
Oesophagus peristaltic waves in the oesophagus carry the bolus to the stomach
Stomach mechanical the stomach acts as a storage container and peristaltic waves mix the food up stomach
Valves at either end of the stomach prevent the escape of food from the chemical the stomach secretes acid and proteolytic enzymes which begin the digestion of proteins
Small intestine this is the region of the digestive system in which most of the digestion takes place chemical the pancreas produces a complete array of enzymes: proteases, amylases, lipases and nucleases.
The pancreas produces an alkaline solution (bicarbonate) to neutralize the acidic material coming from the stomach
The gall bladder releases bile into the small intestine which hewlps in the digestion of fats by emulsifying the fat mechanical the walls of the small intestine are lined by small projections called villi and it is through these that the products of the digestion of food are absorbed contents are moved through the small intestine by peristalsis
Large intestine The major function of the large intestine is to remove water and prepare the solid waste for elimination. The large intestine also serves as a home for an important array of bacteria.
Rectum Material is constantly arriving from the large intestine. The function of the rectum is to store solid waste so that elimination can happen less frequently rather than constantly. When the rectum is full, nerve signals will cause the elimination of the solid material in a process called defecation.
BONUS QUESTION (5 marks)
Digestion of the food takes place outside the body. Do you agree or disagree with this statement? Justify your choice.
Even though the digestive system is inside the body, it is in fact a tube that runs continuously from the mouth to the anus
– a fact that many students find surprising.
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
Lab 5A: The Digestion of Starch
Introduction
The digestive tract is essentially a tube that runs through the body. In order for the nutrients in the food to be available for use in the body, the large molecules in our food need to be broken down. The smaller nutrient molecules can then pass through the walls of the digestive system and enter the blood stream.
The digestion of starch starts in the mouth by the action of an enzyme, salivary amylase. You will investigate this process and demonstrate the break down of starch by salivary amylase and the movement of the smaller molecule, glucose, through a selectively permeable membrane. In preparation for this lab review the starch test, and the structure of starch and of glucose from Module 1.
Materials distilled water or water that has been sitting overnight unsalted soda cracker starch solution tincture of iodine glucose test strips
Apparatus several small drinking glasses
4 baby food jars dialysis tubing
Method string
1. Collect all the materials required for the lab and prepare your laboratory space. Read the method over ahead of time so that you have a general overview of what you will be doing.
2. Place an unsalted soda cracker in your mouth and chew it up until it forms a moist paste in your mouth.
Hold this in your mouth until you begin to notice a taste difference. Describe this taste difference in the
Results section.
3. The source of salivary amylase for the experiment is your saliva. Label a drinking glass “salivary amylase”.
Rinse your mouth out well. Take a mouth full of water and swish it around your mouth. Hold it in your mouth for several minutes (think thoughts that will make your mouth water!) When the time is up, spit the water in a clean drinking glass. Repeat this until you have collected about 100 mL of saliva solution. Keep this solution warm by placing the jar in a water bath (you can use the sink for this) in which the water is about 37
C (body temperature).
4. Remove two small samples (about 5 mL) of the solution and place them in jars. Test one of the samples with tincture of iodine and the other with a glucose strip. Record your results in the Table 5.1.1 note: only record observations
5. Place about 50 mL of water in a glass jar labelled “reaction container” and place the jar in the warm water bath. Test two 5 mL samples of the water with tincture of iodine and a glucose test strip. Record your results in Chart 5.1.1.
6. Cut a strip of dialysis tubing about 20 cm long. Thoroughly wet the tubing with water. Crimp one end of the tubing and tie it off with string. This must be done so as to produce a water tight seal.
7. The dialysis strip is in fact a tube of dialysis membrane. It can be opened up to form a tube (now closed at one end). Using a wet toothpick, or the blunt end of a needle, probe for an opening at the top corner of the tube. Once you have created a small opening, carefully enlarge it so that it can hold about 10 mL
8. Place about 10 mL of starch solution in the warm salivary amylase solution. Mix thoroughly. Transfer some of this solution into the cavity in the dialysis tubing. Use this liquid to help open the rest of the tube. Add more salivary amylase/starch solution until you have about 50 mL inside the dialysis tube. Close off the open end of the dialysis tubing creating a water tight seal. Quickly rinse the outside of the dialysis tube.
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
9. Place the dialysis tube containing the salivary amylase/starch solution in the warm water in the reaction container. Keep this jar in the warm water bath for about 20 minutes.
10. After 20 minutes, remove the dialysis tube from the reaction container. Open the tubing and place half the contents in each of two clean jars. Test one jar with tincture of iodine, and one with the glucose test strip.
Record your results in Chart 5.1.2.
11. Divide the water from the reaction container between 2 clean jars. Test one half with tincture of iodine, and one with a glucose test strip. Record your results in Chart 5.1.2
12. Clean up your laboratory space and replace all equipment
Results
Chewed soda cracker
Chart 5.1.1 testing salivary amylase solution the starch test will be negative iodine glucose test strip the glucose test should also be negative testing water before starch test will be negative iodine glucose test strip glucose test will be negative
After 20 minutes iodine glucose test strip testing dialysis tubing contents positive starch test (not all starch will be broken down) positive glucose test iodine glucose test strip testing the water after 20 minutes starch test will be negative (starch cannot pass through dialysis membrane) glucose test will be positive (there may be a problem with dilution detectable
– the trace colour is close to the negative colour, but it should still be
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
Thinking About the Results
1. After a while you should begin to taste sweetness in your mouth. What can account for the developing sweet taste and what chemicals are involved in this? (remember enzyme action: enzyme, substrate, product)
The digestion of carbohydrates starts in the mouth with salivary amylase. Normally the chewed material is swallowed before the effect can be noticed. Holding the cracker in the mouth for a while allows for enough glucose to be generated to be tasted.
2. Explain what happened in this experiment.
Starch was placed inside the dialysis tubing. The salivary amylase brokle it down to glucose, and the glucose was detected outside the dialysis tubing.
3. Glucose is a monomer and starch is a polymer. Use this idea to explain the experimental results.
(remember that dialysis tubing is a selectively permeable membrane; also remember the process of hydrolysis)
Starch is a polymer and is too big a molecule to pass through the pores of the dialysis tubing. Glucose, the monomer making up glucose, can pass through the dialysis tuning. It diffuses along its concentration gradient from the inside of the dialysis tubing to the outside of the dialysis tubing.
Congratulations, you have now completed Lab 5A
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
Lab 5B: The Senses
Answer the questions in the spaces provided.
Introduction
The senses evolved to allow a organism to collect the information about its environment required for survival and reproduction. In this activity we are going to look at a few of lesser known consequences of the design of our sensory system.
A.
Locating the blind spot
Examine Figure 14.6 in your text.
In this exercise, you will find the entry point of the optic nerve into the interior of the eye. At this entry point there are no sensory receptors (rods and cones), and therefore, it is a blind spot within your field of view.
1.
Hold the page at arm’s length. (Some students may need to start from a point a bit past arm’s length).
2.
Close your left eye.
3.
Stare at the cross with your right eye.
4.
Continue staring at the cross as you slowly move the paper towards directly your head. Do not move the paper sideways in order to see the dot! Measure the distance of the paper from your eye when the dot disappeared.
5.
Repeat the procedure with the right eye closed and stare at the dot with your left eye.
6.
Describe what happened.
As the book is drawn toward the face the dot will disappear. This happens when the image of the dot falls on the position where the optic nerve passes through the retina.
7.
At what distance was your blind spot?
Results will vary
8.
Normally, we are not bothered by the blind spot. How does the eye compensate for the presence of a blind spot in each eye?
The blind spots of the two eyes do not correspond in our visual field. The right eye makes up for the blind spot of the left eye, and the left eye makes up for the blind spot of the right eye.
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
B.
The Sense of Touch – Two Point Discrimination
You can remember seeing a car coming towards you at night. In the distance, the headlights appear as a single light. As the car approached, at a certain distance, the two headlights becomes individually visible. The distance at which the single light can be seen as two relies on the resolving power of your eyes.
The situation is similar for your skin. If two points are placed close together, on some locations the points will feel like a single point, and in other places, your sense of touch will be able to resolve the stimulus into two distinct points.
Sharpen 3 pencils (or use 3 skewers) Attach two of them together them together with tape so that the points are even with each other. Using the areas of skin mentioned in Table 5.2.1, touch the person with the single pencil, then with the double pencil and ask them what they felt. Record these results as trial 1 and trial 2. Continue with the other areas of skin alternating using the single pencil first or the double pencil first. Ask the person to indicate whether she or he feels one point or two points. Record the responses in Table 5.2.1
Table 5.2.1: Number of points felt in different body areas (felt as 1 or 2 points)
Number of points felt Spot tested
Wrist
Thumb tip
Cheek
Lip
Middle of back
Thigh trial 1 trial 2
The results will vary. Two point discrimination not only depends on the sensitivity of the area, but also on the density of touch receptors
How does the number of touch receptors in a given location of the body relate to that location’s function?
It should be clear that two point discrimination is best on the areas of skin whose sensitivity has a survival advantage.
C.
The Goldilocks Effect (not too hot, not too cold – just right!)
We can all remember stepping into a hot shower. Initially it feels like the water is scalding, but, given a bit of time, it begins to feel “just right”. This happens because of the way our skin senses temperature. The environmental temperature is judged by comparison to the skin temperature.
Collect 3 containers into which you can easily insert your hand. Fill one with ice water, one with lukewarm water
(about 40 C) and the other with very hot water.
Place your right hand in lukewarm water. Place your left hand in the “hot” water and keep it there for about 1 minute. Remove it from the hot water and place it in the lukewarm water. Describe the sensation.
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BIOL0601Provincial Biology: Module 5: Human Physiology and Anatomy 2
Wait a few minutes for your hand to recover (or use the other hand), then repeat the process, only this time place your hand in the ice water first, then in the lukewarm water. Describe the sensation
The lukewarm water felt hot when the hand was in ice water first, and it felt cold when the hand was first in hot water.
Why temperature of the lukewarm water does not change significantly, yet it felt both hot and cold. How could this be?
This happens because the body measures temperature in a relative way. Compared to ice water, lukewarm water initially feels quite hot.
Relate the results to everyday life (hint: think of taking a shower or hot bath)
Stepping in to a hot shower or a hot bath is a gradual thing. The water initially feels very hot because our skin temperature is relatively low. As it worms up, the water feels less and less hot.
Congratulations, you have now completed Lab 5B.
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