| Biology 449 - Animal Physiology | Spring 2004 |
Answers in italics
Multiple choice: As always, choose the best answer for each multiple-choice question. Answer on your scantron form. Each question is worth 3 points. You will receive 2 points just for turning in your exam.
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1. Claude Bernard was
a. a world-famous mime.
b. a Belgian detective.
c. Canada’s prime minister.
d. that guy who grew the peas.
e. the father of modern physiology.
2. In one of the negative feedback loops controlling calcium levels, which of the following would be an efferent pathway?
a. the parathyroid gland.
b. parathyroid hormone.
c. the kidneys.
d. the intestines.
e. the bones.
3. With regard to thermoregulation in humans, which of the following mechanisms will tend to decrease the rate of heat loss a person experiences?
a. Decreased blood flow to the skin.
b. Decreased metabolic rate.
c. Increased shivering.
d. Increased sweating.
e. Two of the above.
“a” was what I had in mind, but given the phrasing of the question “b” is also correct, so “e” was also accepted.
4.
The rate of diffusion of a solute across a membrane may depend on all of
the following except
(Note that I am not asking specifically about the Fick equation.)
a. the concentration difference across the membrane.
b. the charge across the membrane and the charge of the solute.
c. the surface area of the membrane.
d. the thickness of the membrane.
e. All of the above may influence the rate of diffusion.
5. We have one liter each of two solutions: A and B. A and B both contain one mole of dissolved particles, but they may differ in composition. We arrange A and B so they are separated by a semi-permeable membrane, and find that the volume of B increases while the volume of A decreases. Which of the following statements best describes the situation?
a. A is hyposmotic relative to B, but A and B are isotonic.
b. B is hyposmotic relative to A, but A and B are isotonic.
c. A and B are isosmotic, but A is hypotonic relative to B.
d. A and B are isosmotic, but B is hypotonic relative to A.
e. A and B are both isosmotic and isotonic.
6. Secondary active transport involves
a. two channel proteins.
b. a channel protein and a carrier protein.
c. two carrier proteins.
d. Secondary active transport may involve two of the above.
e. Secondary active transport may involve any of the above.
7. The spinal cord is considered part of the
a. central nervous system.
b. peripheral nervous system.
c. afferent nervous system.
d. sympathetic nervous system.
e. parasympathetic nervous system.
8. Which of the following should help improve the rate of action potential propagation in an axon?
a. Better cable properties.
b. Larger axon diameter.
c. Regions of myelination alternating with nodes of Ranvier.
d. Two of the above.
e. All of the above.
9. In synaptic transmission, the movement of the neurotransmitter across the synaptic cleft to the post-synaptic neuron is the result of
a. being carried across the cleft in synaptic vesicles.
b. sliding along actin filaments to the post-synaptic neuron.
c. bulk flow of synaptic fluid containing the neurotransmitter.
d. diffusion from the pre-synaptic to the post-synaptic neuron.
e. movement of cilia on the post-synaptic neuron.
10. In neural synapses, G-proteins are associated with
a. synaptic vesicle release.
b. ionotropic receptors.
c. metabotropic receptors.
d. fast synaptic transmission.
e. the enzymatic breakdown of neurotransmitters.
11. Which of the following would normally have an inhibitory effect on a neuron?
a. opening sodium channels in the membrane.
b. opening potassium channels in the membrane.
c. closing potassium channels in the membrane.
d. a and b.
e. a and c.
12. A sensory receptor that showed rapid adaptation to a stimulus would be classified as a(n)
a. adaptive receptor.
b. dynamic receptor.
c. encoding receptor.
d. phasic receptor.
e. tonic receptor.
13. Which of the following is true with regard to the olfactory system?
a. Each olfactory receptor responds to only one odorant (airborne chemical).
b. Most odorants activate olfactory receptors directly via ligand-gated channels.
c. Odorants activate olfactory receptors via G-protein systems.
d. Material must be dissolved in the saliva to be sensed by the olfactory system.
e. The cilia of olfactory receptors have the same structure as bacterial flagella.
14. The molecule in rod cells that has its structure altered when struck by light is
a. cGMP.
b. opsin.
c. phosphodiesterase.
d. retinal.
e. transducin.
15. Given what we learned in class about testosterone, it could be classified as
a. an autocrine agent.
b. a paracrine agent.
c. a hormone.
d. Two of the above.
e. All of the above.
16. The release of adrenocorticotropic hormone is promoted by
a. dopamine.
b. corticotropin releasing hormone.
c. gonadotropin releasing hormone.
d. somatostatin.
e. thyrotropin releasing hormone.
17. In most mammals, increasing cortisol levels help the animal survive a stressful situation by
a. mobilizing energy stores.
b. increasing immune function.
c. initiating the “fight-or-flight” response.
d. prompting it to curl up in a little ball.
e. providing Hulk-like strength.
18. A myofibril is
a. a bundle of muscle cells.
b. an individual muscle cell.
c. a bundle of thick and thin filaments.
d. one thick or thin filament.
e. an individual myosin molecule.
19. As a sarcomere shortens from its normal resting length, the force produced first starts to drop because
a. ATP levels begin to drop.
b. calcium can no longer diffuse to the thin filaments as effectively.
c. the thin filaments start to interfere with each other.
d. there is less overlap between the thick and thin filaments.
e. The sarcomere cannot shorten beyond its normal resting length.
20. A muscle will produce the greatest amount of force during
a. an isometric twitch contraction.
b. an isometric tetanic contraction.
c. a light load isotonic twitch contraction.
d. a medium load isotonic twitch contraction.
e. inactivity.
21. The appropriate kind of exercise can typically result in
a. conversion of slow-oxidative to fast-oxidative fibers.
b. conversion of fast-oxidative to fast-glycolytic fibers.
c. an increase in the number of muscle fibers.
d. Two of the above.
e. All of the above.
22. The blood vessels carrying blood at the lowest pressure are the
a. arteries.
b. arterioles.
c. capillaries.
d. venules.
e. veins
23. The short delay between the action potentials in the atria and the action potentials in the ventricles
a. is the unavoidable result of slow conduction.
b. serves to let the ventricles rest between beats.
c. allows the atrial contraction to move blood into the ventricles before they contract.
d. provides different blood pressures for the pulmonary and systemic circulation.
e. There is no delay between the AP’s in the atria and the AP’s in the ventricles.
24. Starling’s Law of the Heart states that
a. heart rate increases with increasing stroke volume.
b. heart rate increases with increasing venous return.
c. heart rate increases with increasing arterial pressure.
d. stroke volume increases with increasing heart rate.
e. stroke volume increases with increasing venous return.
25. At 3000 meters elevation, atmospheric pressure averages 528 torr. What would be the expected partial pressure of oxygen in the air at this altitude? (Oxygen is 21% of air.)
a. 528 torr.
b. 160 torr.
c. 110 torr.
d. 40 torr.
e. 5 torr.
26. The effect of a right-shift in the oxygen saturation curve of hemoglobin would normally be
a. a decrease in oxygen loading at the lungs and an increase in oxygen unloading at the tissues.
b. little change in oxygen loading at the lungs and a decrease in oxygen unloading at the tissues.
c. little change in oxygen loading at the lungs and an increase in oxygen unloading at the tissues.
d. an increase in oxygen loading at the lungs and a decrease in oxygen unloading at the tissues.
e. an increase in oxygen loading at the lungs and an increase in oxygen unloading at the tissues.
27. Which of the following is the major form of transport for carbon dioxide in the blood?
a. Gaseous carbon dioxide.
b. Dissolved carbon dioxide.
c. Bicarbonate ion.
d. Carbonic anhydrase.
e. Carbamino compounds.
28. The peripheral chemoreceptors that help control the ventilatory response to increasing CO2 levels in the blood respond directly to
a. PCO2 itself.
b. H+ concentration.
c. HCO3- concentration.
d. H2O concentration.
e. PO2.
29. The direction of movement of a gas between two respiratory pigments (such as hemoglobin and myoglobin) can be determined by
a. differences in the concentration of the gases alone.
b. differences in the saturation of the two pigments alone.
c. differences in the partial pressure of the gases alone.
d. differences in the molecular weights of the gases alone.
e. All of the above.
30. The main type of digestive enzyme found in saliva is
a. amylase.
b. lipase.
c. peptidase.
d. protease.
e. salivase.
31. The section of the GI tract absorbing the most water is the
a. stomach.
b. small intestine.
c. pancreas.
d. liver.
e. large intestine.
32. Most tissues in the body burn glucose rather than fatty acids for energy in response to
a. increased insulin.
b. decreased insulin.
c. increased glucagon.
d. decreased glucagon.
e. their own measurement of blood glucose levels.
33. The absorptive phase normally lasts how long after a typically-sized meal?
a. 30 minutes.
b. 1 hour.
c. 4 hours.
d. 8 hours.
e. 24 hours.
34. The main nitrogenous waste product found in humans is
a. ammonia.
b. creatinine.
c. nitric oxide.
d. urea.
e. uric acid.
35. If a substance is found in the final urine at the same concentration as in the initial glomerular filtrate, it must have been.
a. reabsorbed.
b. secreted.
c. neither secreted nor reabsorbed.
d. a or c is possible.
e. It is not possible for this to happen.
36. As primary urine passes through the proximal tubule it
a. becomes more concentrated.
b. becomes less concentrated.
c. increases in volume.
d. decreases in volume.
e. Two of the above.
37. Levels of ADH control urine concentration by
a. controlling filtration rate at the renal corpuscle.
b. altering the permeability of the descending loop of Henle to water.
c. affecting the activity levels of sodium transporters in the ascending loop of Henle.
d. altering the permeability of the collecting duct to water.
e. affecting the activity levels of sodium transporters in the collecting duct.
38. During the early to mid follicular phase in women, the hormone with the most direct negative feedback effect on follicle-stimulating hormone release is
a. estrogen
b. FSH itself.
c. inhibin.
d. luteinizing hormone.
e. progesterone.
39. The corpus luteum arises from
a. the dominant follicle after the release of the oocyte.
b. one of the secondary follicles that did not release an oocyte.
c. other ovarian tissue.
d. pituitary tissue.
e. the oocyte itself.
40. Sperm (spermatozoa) are produced by the
a. Leydig cells.
b. Sertoli cells.
c. spermatogonia.
d. epididymus.
e. seminal vesicle.
“c” is what I had in mind, since by “are produced by” I meant “give rise to” or “form”. But so many people chose “b” I couldn’t be sure the question wasn’t misunderstood. But Sertoli cells only promote sperm production.
41. Emission in males could best be described as
a. the maturation of the sperm.
b. the process by which the penis becomes rigid.
c. the mixing of the sperm with various fluids and chemicals to form the semen just prior expulsion.
d. the expulsion of the semen from the penis.
e. an unpleasant body odor.
42. The process of parturition can be described as a
a. negative feedback loop.
b. positive feedback loop.
c. feedforward loop.
d. regulated system.
e. homeostatic system.
43. Immune cells that specialize in attacking parasites include
a. eosinophils.
b. lymphocytes.
c. mast cells.
d. monocytes.
e. neutrophils.
44. An example of a lymphoid tissue is.
a. lymph nodes.
b. the spleen.
c. the tonsils.
d. the appendix.
e. All of the above are examples of lymphoid tissues.
45. The movement of leukocytes towards chemical signals released in areas of damaged tissue is known as
a. chemotaxis.
b. complementation.
c. cytokinesis.
d. inflammation.
e. opsonization.
46. Natural killer (NK) T cells
a. are derived from helper T cells.
b. die in the process of killing the cells they attack.
c. kill cells via C3b.
d. attack virus-infected and cancer cells without needing to recognize an antigen.
e. produce memory T cells.
47. In most people, lymphocytes do not end up attacking healthy body cells because
a. it is genetically impossible to create a receptor that binds to a person’s own tissues.
b. B or T cells with receptors that match the person’s tissues do not reach maturity.
c. the MHC complex only presents foreign material.
d. cytokines are not released by helper T cells that recognize an antigen as “self.”
e. Lymphocytes frequently attack healthy body cells.
48. T cell receptors differ from B cell receptors in that
a. T cell receptors are MHC II complexes.
b. B cell receptors are MHC II complexes.
c. B cell receptors have two “arms” while T cell receptors have only one.
d. B cell receptors can bind to antigens while T cell receptors cannot.
e. T cells do not have receptors.
49. Macrophages release which of the following to help activate helper T cells?
a. Interleukin-1
b. Interleukin-2
c. Tumor necrosis factor
d. Interferon
e. Two of the above.
50. Memory B, T and helper T cells are most important in
a. the primary immune response.
b. the secondary immune response.
c. non-specific immune responses.
d. releasing antibodies.
e. killing infected cells.
Short answer: Write a concise answer to each of the following questions. Your answers should fit in the spaces provided. Each question is worth 4 points. When appropriate, you are welcome to use a diagram in your answer, but be sure all events and processes are made clear. If you are uncertain about the nature of the question, please ask!
51. Describe
the process by which an action potential is generated. You do not need
to describe the propagation of the action potential along an axon or what causes
the refractory period.
An action potential occurs in a neuron or myofiber when the membrane is
depolarized above the threshold potential. This depolarization triggers the
rapid opening of the activation gates of voltage-gated sodium channels, which allows
movement of positive sodium ions into the cell, further depolarizing the
membrane and opening additional sodium channels. This positive feedback loop
causes rapid influx of sodium ions and depolarization of the membrane to a
positive potential. But the depolarization also triggers two slower phenomena –
closing of the deactivation gates in the sodium channels and opening of
potassium channels. The combination of decreased sodium permeability (back to
resting levels) and increased potassium permeability rapidly repolarizes the
membrane, and the latter temporarily hyperpolarizes the membrane, until the
potassium channels close again.
52. Describe
the process of lateral inhibition, explaining how it helps augment perception
if a localized sensory stimulus.
Stimulation of a sensory cell normally causes it to increase stimulation of
a secondary neuron, which carries the signal to the CNS. In lateral inhibition,
the sensory cell also directly or indirectly inhibits the activity of the
secondary neurons associated with adjacent sensory cells, so that increased
stimulation of the sensory cell causes not only an increase in the AP
frequency from its associated neuron, but also a decrease in AP frequency from
the surrounding neurons. Thus the signal of the stimulated neuron becomes
proportionately stronger relative to the decreased signal of nearby cells.
53. Explain
briefly how hair cells (such as those found in the organ of Corti) transduce
mechanical stimulation into a series of action potentials in afferent neurons.
The “hairs” of the hair cells – the stereocilia and kinocilium – are
attached to or embedded in some structure that causes the hairs to be bent when
mechanical stimulation occurs. The bending of the hairs causes potassium
channels in the hairs to either open or close, depending on the direction of
bending. This results in a depolarization or hyperpolarization of the cell, so
that bending one way versus the other results in more or less neurotransmitter
release and thus increased or decreased AP’s in afferent neurons.
54. What
are the two classes of hormone receptors (hint: where is the membrane receptor
located)? For each, describe briefly (one or two sentences) how it works, and
give an example of a hormone that activates this type of receptor.
Membrane receptors – these are the most common type, bound in the cell
membranes, that typically act by activating a G-protein complex and/or an
enzyme cascade. An example is any hormone other than those listed below.
Intracellular receptors – these are less common, and occur only for
lipophilic hormones that can pass through the cell membrane. Once activated,
these receptors directly affect gene expression, increasing or decreasing
protein synthesis rates. Examples include the steroid hormones (from the
adrenal cortex or gonads) and the thyroid hormones.
55. What
is the difference, if any, between “contraction” and “shortening” with regard
to muscles?
“Contraction” is the generation of force, or in other words the activation
of cross-bridge cycling. “Shortening” is a decrease in length of the muscle
fiber or whole muscle. Contraction occurs without shortening during an
isometric contraction.
56. What are the two general
factors that determine mean arterial blood pressure, and what is the equation
that relates all three of these variables? Indicate which variable is normally
regulated.
Arterial blood pressure is determined by cardiac output and total peripheral
resistance: MAP = CO ´ TPR.
The variable that is regulated is MAP. The other two variables are
adjusted to maintain, or regulate, blood pressure.
Explain what happens to each of the variables during exercise, being sure you
explain why each is changing (or not changing).
During exercise, increased demand for oxygen in working muscles leads to
vasodilation in these tissues. By itself, this vasodilation would tend to
decrease TPR. To help compensate, other tissues experience varying degrees of
vasoconstriction, helping to offset the change in TPR. But TPR does still
fall, and so cardiac output must be increased to maintain MAP at a roughly
constant level.
57. A person suffering a
pneumothorax has a whole in his chest that allows air to freely enter the
intrapleural space, so that the pressure of the intrapleural fluid will equal
atmospheric pressure. What do you think would be the likely effect on thoracic
volume and lung volume, and on the person’s ability to breathe?
Normally, the negative (relative to atmospheric) pressure in the
intrapleural space counters the tendency of the lungs to collapse and the ribcage
to expand. If that negative pressure is lost, the lung volume will decrease
and the thoracic volume will increase. Since the lungs are no longer held
against the ribcage by negative pressure, they cannot be inflated and breathing
will not be possible.
58. What is the hormonal
response to the presence of proteins and fats in the small intestine, and what
are the results of this response? (You do not need to discuss specific enzymes
or other details of digestion or absorption.)
Proteins and fats in the SI promote the release of cholecystokinin, which
promotes the release of agents that promote the breakdown and digestion of
these materials: proteases, lipases (and amylase) from the pancreas and bile
from the liver/gall bladder.
59. Describe the feedback loop
involving renin. Be sure it is clear what the effect of each chemical
substance is (for example, A promotes the release of B by the
gland C, or X converts Y into Z).
Decreased BP and decreased [Na+] in the distal tubule cause the
kidneys to increase their release of renin, an enzyme. Renin converts
angiotensinogen, which is constantly released by the liver, into angiotensin
I. Angiotensin I is then converted into angiotensin II by an enzyme
(angiotensin converting enzymes) found in the capillaries, particularly in the
lungs. Angiotensin II is a hormone with (at least) two effects. One is to
increase vasoconstriction, thus increasing BP; the other is to promote the
release of another hormone, aldosterone, from the adrenal cortex. Aldosterone
then promotes increased reabsorption of sodium by the distal tubule, increasing
blood [Na+].
60. If
you were to drink a very large quantity of an isosmotic drink, your blood
volume could increase (without changing concentration) to the point where you
were hypervolemic – in other words, you blood volume would be too great. What
might be three physiological responses to this situation, over either the short
or long term?
Note that the drink is isosmotic, so changes in ECF concentration are not an
issue – this is strictly a volume issue. The main problem you would face is
the opposite of what occurs during hypovolemia – the volume increase would tend
to increase BP. Responses could include vasodilation and decreased cardiac
output (via decreased HR and/or SV) in the short term, and increased urinary
output in the long term. But again, note that the intake was isosmotic, so the
output will be, too – copious isosmotic, not hyposmotic, urine.
Aside from their effects on the
endometrial layer of the uterus, what are four effects (total) of estrogen and
progesterone on a woman’s body during pregnancy? Be sure you specify which
hormone is responsible for each effect.
Estrogen:
Enlarges uterus and increases uterine muscle
Relaxes pelvic ligaments
Causes further mammary gland development (ducts and fat)
Promotes prolactin release, which further promotes breast growth and mammary
gland development.
Increases uterine sensitivity to oxytocin.
Inhibits lactation during pregnancy
Progesterone:
Maintains secretory phase conditions in uterus
Increases mammary development (glandular tissue)
Inhibits premature uterine contractions
Inhibits lactation during pregnancy
61. List and briefly (one or two
sentences) describe four ways in which antibodies help to kill organisms like
bacteria and viruses.
Neutralization – Bound antigen has activity blocked – often prevents viri or
bacteria from adhering to host cells, etc.
Enhancement of phagocytosis – Antibodies bind to receptors on phagocytes,
triggering phagocytosis
Agglutination – Each antibody has two binding sites (and IgM is a pentamer) so
large numbers of molecules or microbes can end up stuck together. Encourages
phagocytosis and/or precipitation.
Activation of complement system – In addition to non-specific response, this
system can be activated by bound antibodies. Results in placement of membrane
attack complex in bacterial membrane
Extra credit question (4 points)
Arteriosclerosis is
hardening of the walls of the arteries, caused by the deposition of calcium and
a change in the structure of the collagen in the elastic layers of the vessels.
It appears to be a normal consequence of aging. (The related atherosclerosis
has similar effects, but involves localized plaques and apparently has dietary
origins. But I digress.). What might be the effects of the loss in arterial
elasticity with regard to systolic and diastolic arterial blood pressure, and
why?
The elasticity of the arterial walls allows the arteries to expand during
systole, thus helping to reduce the increase in pressure in these vessels.
During diastole, the elasticity maintains pressure on the blood in the arteries
despite the pressure of ~0 torr in the ventricles. If the arteries were not as
elastic, we’d expect to see an increase in systolic pressure, and a decrease in
diastolic pressure.