| Biology 449 - Animal Physiology | Spring, 2001 |
Answers are in italics
Multiple choice: As always, choose the best answer for each multiple-choice question. Answer on your scantron form. Each question (except 1) is worth 3 points.
1. Fill in your scantron form as follows: (2 point)
a. Really, I swear, I did it all.
2. Which of the following fluid spaces is not considered to be part of Bernard’s "internal environment"?
a. Intracellular fluid
3. During a fever, body temperature rises and then is maintained at a temperature several degrees above normal. Which component of the negative feedback loop controlling temperature must have changed for this to occur?
d. The temperature setpoint
4. According to the Fick equation, which of the following will increase the rate of diffusion from one area to another?
c. An increase in the difference in concentration between the two areas
5. The osmolarity value of a solution by itself indicates
b. the concentration of particles dissolved in the solvent
6. The sympathetic nervous system is part of the
d. autonomic nervous system
7. The Nertz equation is less useful than the Goldman equation for calculating membrane potentials under real physiological conditions because
c. the Nertz equation does not account for the presence of more than one ion.
8. Which of the following help to repolarize the neuron membrane during an action potential?
b. The closing of sodium channels
and
c. The opening of potassium channels
so the correct answer is
e. More than one of the above
9. Which of the following would be specifically associated with the presence of nodes of Ranvier on an axon?
a. Saltatory conduction
and
b. Myelin
so the correct answer is
d. Two of the above
10. Which of the following is not typical of fast chemical synaptic transmission?
b. G-protein complexes
11. Which of the following would likely be the effect of the neurotransmitter released by an inhibitory neuron?
d. Increased flow of chloride ions into the neuron
12. Receptors for ACh are known as
e. cholinergic receptors.
13. Which of the following is most useful in amplifying small stimuli in sensory neurons?
My apologies on this one - I didn't reread it carefully enough after changing the question. The answer I originally had in mind was "b", but "e" is also acceptable.
b. G-protein complexes
or
e. Transducin
14. A phasic receptor has delivers action potentials at a frequency proportional to
c. the rate of change of stimulus intensity.
15. A sensory cell associated with the gustatory system would most likely be a
d. chemoreceptor
16. The auditory system involves
a. mechanical amplification.
b. pressure waves.
and
c. membrane flexion.
so the correct answer is
e. All of the above
17. An eye containing only rod-type cells would most likely be associated with
b. a nocturnal predator.
18. Which of the following does not travel through the blood stream to carry its “message”?
d. A paracrine agent
19. Which of the following hormones inhibits the release of prolactin?
c. Dopamine
20. The hormone most directly associated with the stress response is
a. cortisol.
21. The calcium ions that enter the myofibril during excitation-contraction coupling
c. move out of the sarcoplasmic reticulum down their concentration gradient.
22. Which of the following is associated with the thin filaments of skeletal muscles?
d. Troponin
23. Which of the following would be characteristic of a slow oxidative muscle fiber?
e. High mitochondrial content.
24. The bundle of His
b. transmits electrical excitations through the myocardium.
25. Starling’s “Law of the Heart” states that
c. increased blood return to the heart increases the stroke volume.
26. Which type of blood vessel has the greatest total cross-sectional area?
c. Capillaries
27. Which of the following would be expected to increase the rate of fluid loss from the capillaries during the formation of lymph?
d. Increasing the osmolarity of the interstitial fluid around the capillary
28. Normal, resting exhalation relies on activation of
e. None of the above
29. The difference between minute ventilation and alveolar ventilation rate is due to
a. the effects of anatomical dead space.
30. The approximate composition of blood returning to the lungs at rest is
b. PO2 = 40 torr, PCO2 = 45 torr
31. Use the graph below to answer the following question.
While working under hypoxic (low oxygen) conditions, a test subject has an arterial PO2 of 70 torr and a venous PO2 of 20 torr. What percent of the maximum oxygen that can be carried by the hemoglobin is delivered to the subject’s tissues?
c. 50%
32. The respiratory control center is located in the
d. medulla oblongata.
33. Which of the following statements is true, given normal resting levels of blood gases as starting conditions?
b. Ventilation is more sensitive to small changes in PCO2 than to small changes in PO2.
34. The first part of the digestive tract in which absorption of nutrients takes place is the
d. small intestine
35. Which of the following is/are not released by the pancreas?
d. Bile salts
36. The transport of glucose across epithelial layers in the gut involves
d. secondary active transport via a symporter
37. One effect of glucagon is
b. increased glucose release by the liver.
38. The renal system is not involved in
e. lymph formation.
39. In what portion of the nephron does glucose get reabsorbed?
a. Proximal tubule
40. The most important function of the high osmotic concentration of the renal medulla is that
e. it allows the formation of a high concentration urine.
41. When levels of ADH are low, which of the following will be the direct result?
c. Decreased recovery of water from the urine
42. For a typical human, maximal metabolic rate is about how many times basal metabolic rate?
c. 10-20x
43. The gene responsible for initiating male development in a fetus is the
d. SRY gene.
44. In the developing fetus, which of the following effects does testosterone have?
a. Causes development of the Wolffian ducts
45. The first sign of the onset of puberty would be
a. increased levels of gonadotropin releasing hormone.
46. Spermatogenesis is most directly controlled by
b. Sertoli cells.
47. Which of the following is not part of the reproductive tract in the human male?
c. Ureter
48. The erect state of the penis in men is supported by
e. blood pressure.
49. The follicles of the ovary consist (at some point) of
a. granulosa cells.
b. thecal cells.
and
c. an oocyte.
so the correct answer is
e. All of the above
50. The proliferative phase of the uterine cycle involves growth of the
d. endometrium.
51. In humans, the period of time each month during which sexual intercourse can lead to fertilization is about
d. three days.
52. Which of the following statements is true?
b. During pregnancy, the fetal tissue first stimulates the mother to release estrogen and progesterone, then produces these hormones itself.
53. The most important hormone in parturition is
d. oxytocin.
54. Lactation generally begins only after the birth of a child because
d. milk production is inhibited by high levels of progesterone and estrogen.
Short answer: Write a concise answer to each of the following questions. Your answers should fit in the spaces provided. Each question is worth three points unless otherwise noted.
55. Briefly describe three different means by which a substance may move across or through a membrane when movement is with the substance’s concentration gradient. (These mechanisms were discussed at the same time as mechanisms for moving up a gradient; i.e. active transport.)
The answers I was looking for were "simple diffusion" (diretly through membranes), "permeation" (channel proteins), and "facilitated diffusion" (carrier proteins). However, I will also accept "osmosis" as one of the three.
56. What is the dynamic range of a sensory system? Describe one mechanism that may help expand this range.
Dynamic range simply refers to the maximum and minimum stimulus strength that a sensor (or family of sensors) can provide useful information about. Mechanisms to help expand this range include having different sensors for different stimulus strengths and sending APs at frequencies proportional to log(stimulus strength) rather than directly proportional to stimulus strength.
57. List three important differences in nerves and hormones, with regard to their role in carrying messages or signals to various effectors.
What I had in mind here was a comparison of factors such as the speed of message transmission (very fast in nerves, slower in hormones), the specificity of the target (nerves carry signals to one organ or set of cells while hormones travel throughout the body), and the longevity of the signal (nerves often turn "off" again very quickly, while hormones may influence their targets for days). Many other answers are possible here, and I'll be fairly liberal in what I accept.
58. Give an example of a two-pigment system for carrying oxygen. Indicate which pigment has the higher affinity for oxygen.
The examples we discussed in class are the hemoglobin-myoglobin system and the maternal Hb - fetal Hb system. In each case, the higher affinity pigment is the second one listed.
59. Describe the steps involved in excitation-contraction coupling. You can do this in list form. You do not need to describe the details of myosin-actin cross-bridge cycling. (6 points)
There is obviously some variability here in what people will include. For example, relaxation of the muscle is not part of contraction per se, and so need not be listed to get full credit. Here is an abbreviated version excitation-contraction
- An A.P. at the motor nerve causes neurotransmitter (acetylcholine) to be relased
- ACh triggers opening of ion channels, casuing sarcolemma depolarization and an action potential on the muscle's surface. The A.P. travels down the T-tubules
- A.P. in tubule triggers DHP, which triggers ryanodine to openCa2+ channels in adjacent S.R.
- Ca2+ diffuses into lumen and binds to troponin. Tropomyosin moves, exposing myosin-actin binding sites, and cross-bridge cycling occurs.
- Ca2+ is taken back into the S.R. by ATP-powered transporters.
- Troponin is no longer bound by Ca2+ and contraction stops.
60. List three functions of the liver.
Many are possible. Some examples are release of bile salts, release of bicarbonate, storage of glucose as glycogen, release of glucose during the post-absorptive phase, and detoxification of the blood.
61. If blood pressure drops, a number of physiological responses may occur to help correct this problem.
a. Name one mechanism used to help increase blood pressure over the short-term
This will relate to factors affecting blood flow and peripheral resistance, such as an increase in heart rate and peripheral vasoconstriction.
b. Name two mechanisms used to help increase blood pressure over the long-term
These will relate to increasing blood volume. Increases in salt and water retention by the kidneys (via aldosterone and ADH) are examples, as are increased thirst/drinking.
62. Answer the following questions using the graph below. (6 points)
The graph represents a single female menstrual cycle.
a. The graph needs to show the relative levels of luteinizing hormone, estrogen and progesterone.
- Label the existing line as one of these three hormones.
- Add the lines for the remaining two hormones to the graph, and label each line. (Note: it is only the change of each hormone through time that is important, not the absolute levels of the hormones to one another.)
The graph shown here includes these new lines and labels. I will generally be looking for trends rather than exact values or patterns when grading these graphs.
b. For each of the following events, place the corresponding number at the appropriate time on the graph.
Locations of the events are approximate - again there is room for variation, moreso for some events than others.
(1) The egg is released from the ovary
(2) Positive feedback loop for estrogen release begins
(3) Corpus luteum grows and develops
(4) Menstrual phase of uterine cycle
63. Give two effects of estrogen and one of progesterone during pregnancy
Examples are given; other answers are possible
Estrogen (2 effects):
Enlarges uterus and increases uterine muscle
Relaxes pelvic ligaments
Causes mammary gland developmentProgesterone (1 effect)
Inhibits premature uterine contractions
Increases mammary development
64. Describe the changes in the urine as it moves down and then up the loop of Henle. What is entering or leaving the urine, what are the processes involved, and how does urine concentration change? You can include a diagram, but be sure it is explained with text as well.
As the urine moves down the loop, water is drawn out osmotically by the increasingly concentrated interstitial fluid surrounding the nephron. Salt and other solutes generally cannot penetrate the descending limb, so the urine becomes nearly as concentrated as the surrounding fluid.
As the urine moves back up the ascending limb, the tubule becomes permeable to salt but impermeable to water. The highly concentrated urine in the tubule is now surrounded by less concentrated fluid, and salt can move out of the fluid down its concentration gradient. When the thick ascending limb is reached, salt is actively transported out, ultimately resulting in a urine that is hyposmotic to the surrounding fluid.
Bonus question - No penalty for skipping this one!
65. After the death of a person (or other animal), the condition known as rigor mortis is typically observed after a few hours. This condition is a stiffness of all the muscles in the corpse that does not disappear until the tissues begin to decay. Given the clue that rigor mortis occurs when the muscle cells run out of ATP, coupled with your knowledge of muscle physiology, how might you explain this phenomenon?
Since ATP are required to break the cross-bridges between myosin and actin, once ATP stores are depleted actin and myosin will remain bound, and the sliding filaments will no longer slide. This will mean that muscles become stiff and unyielding until the myofibrils begin to break down.