Biology 449 - Animal Physiology

Spring 2006

Final Exam

200 points total

Fill in your scantron form as follows:

· Write and bubble in your name in the upper left, last name first.

· Follow any additional instructions provided in class.

· Sign your form in the upper right.  By so signing, you are indicating that you have followed Creighton’s policy on academic honesty in taking this test.

Multiple choice:   As always, choose the best answer for each multiple-choice question.  If you are uncertain about the nature of the question, please ask!  Answer on your scantron form.  Each question is worth 3 points.

1. Which of the following would not be classified as a physiologically regulated variable?  (Hint: Think carefully about what is meant by “regulated” in this context.)

a. Blood calcium levels

b. Blood pH levels

c. Body temperature

d. Heart rate

e. Total extracellular fluid volume

2. In an investigation into renal function, you find that whenever extra-cellular potassium levels decrease, the level of a newly identified compound in the blood increases.  This compound has a chemical structure similar to cholesterol.  If you inject a dose of the compound into someone, less potassium appears in his urine.  Based on this information and your knowledge of physiology, the compound is probably acting as a(n) ____________ in a negative feedback loop.

a. sensor

b. integrating center

c. efferent pathway

d. effector

e. regulated variable

3. Consider two solutions separated by a semi-permeable membrane.  Solution A contains 1.0M NaCl, while solution B contains 1.0M KCl.  The membrane is permeable to water and Na⁺ only.  If you wished to keep Na⁺ from diffusing from solution A to solution B, which of the following strategies would likely be most effective?

a. Making the membrane permeable to K⁺.

b. Making the membrane permeable to Cl^-.

c. Making the membrane impermeable to water.

d. Adding additional KCl to solution B.

e. Creating a positive charge on the B side of the membrane.

4. In a neuron, action potentials are usually seen in the

a. axon.

b. dendrites.

c. soma.

d. Two of the above.

e. All of the above.

5. The main difference between the Nernst and Goldman equations is

a. the Nernst equation considers only one ion, the Goldman more than one.

b. the Nernst equation does not consider the permeability of the membrane to ion(s), while the Goldman  does.

c. the Nernst equation does not consider the valance of the ion(s), while the Goldman  does.

d. Two of the above.

e. All of the above.

6. Consider an axon to which two substances have been applied – one of these prevents the inactivation gates of the voltage-gated sodium channels from closing, while the other blocks the opening of voltage-gated potassium channels.  If the membrane is depolarized above threshold potential, what would be the expected outcome?

a. no further increase in potential would take place, and the membrane would slowly return to normal resting potential.

b. the membrane would rapidly depolarize and stay depolarized indefinitely.

c. the membrane would rapidly depolarize and then slowly return to normal resting potential.

d. the membrane would rapidly depolarize and then rapidly return to normal resting potential.

e. the membrane would rapidly depolarize and then rapidly hyperpolarize, before returning to normal resting potential.

7. The release of neurotransmitter from a presynaptic neuron depends on the action of

a. ligand-gated calcium channels.

b. voltage-gated calcium channels.

c. ligand-gated sodium channels.

d. voltage-gated sodium channels.

e. G-proteins.

8. In order to be detected by the sensory system, an environmental variable must ultimately bring about

a. a change in cell membrane potential.

b. mechanical deformation of the cell membrane.

c. activation of ligand-gated ion channels.

d. activation of G-protein complexes.

e. the up- or down-regulation of mRNA synthesis.

9. Sensory cells that show rapid adaptation to a change in stimulus intensity are referred to as

a. mechanoreceptors.

b. nociceptors.

c. proprioceptors.

d. phasic receptors.

e. tonic receptors.

10. The number of different types of receptors in the olfactory system of mammals is

a. about five.

b. about a dozen.

c. about a hundred.

d. about a thousand.

e. millions.

11. The transduction of sound from vibrations to action potentials in the mammalian ear occurs in/at the

a. tympanic membrane

b. middle ear.

c. oval window.

d. organ of Corti.

e. round window.

12. A neurohormone is a chemical messenger that

a. affects the central nervous system.

b. affects peripheral neurons.

c. is released by a special class of neurons.

d. triggers the release of other hormones.

e. is released in response to other hormones.

13. The presence of Ca²⁺ in a sarcomere is normally necessary for cross-bridge cycling to occur because

a. Ca²⁺ causes tropomyosin to move away from the myosin binding sites on actin.

b. Ca²⁺ activates the myosin binding sites on actin.

c. Ca²⁺ activates myosin ATPase.

d. Ca²⁺ allows myosin to dissociate from actin after its power stroke.

e. The presence of Ca²⁺ is not normally necessary for cross-bridge cycling to occur.

14. If we say a muscle is shortening, which of the following will normally be occurring?

a. The muscle’s length is decreasing.

b. The muscle is producing force.

c. The muscle is exhibiting cross-bridge cycling.

d. Two of the above.

e. All of the above.

15. A tetanic contraction in a muscle results from

a. a single, short action potential.

b. a single extended action potential.

c. two action potentials.

d. multiple action potentials at high frequency (> 10 per second).

e. multiple action potentials at low frequency (< 1 per second).

16. The muscle fibers in a single motor unit of a human

a. are all the same fiber type.

b. are innervated by multiple neurons.

c. are activated in sequence, with new fibers initiating contracting as old ones fatigue.

d. are fused together into a single super-cell.

e. Two of the above.

17. During a heartbeat, the atrioventricular valves open when

a. the blood pressure in the atria first exceeds pressure in the ventricles.

b. the blood pressure in the ventricles first exceeds pressure in the atria.

c. the blood pressure in the arteries first exceeds pressure in the ventricles.

d. the blood pressure in the ventricles first exceeds pressure in the arteries.

e. There are no atrioventricular valves.

18. A number of different mechanisms can bring about an increase in the stroke volume of the mammalian heart.  One thing all of these mechanisms have in common is that

a. they increase the volume of blood in the heart at the start of systole.

b. they are triggered by the sympathetic nervous system.

c. they are triggered by the parasympathetic nervous system.

d. they involve chemical messengers.

e. they increase the force of contraction by the ventricles.

19. In comparison to all capillaries combined, the aorta has

a. the same blood flow per minute, higher blood velocity and higher blood pressure.

b. higher blood flow per minute, higher blood velocity and higher blood pressure.

c. higher blood flow per minute, the same blood velocity and higher blood pressure.

d. the same blood flow per minute, higher blood velocity and the same blood pressure.

e. higher blood flow per minute, higher blood velocity and the same blood pressure.

20. One of the effects of emphysema is to make the lungs less compliant (that is, less stretchable and thus more resistant to expansion).  At the end of a two liter inspiration, how would the intrapleural pressure of an individual with this disease compare to that of a healthy person?

a. The emphysematic would have a lower (more negative) intrapleural pressure than the healthy person.

b. The emphysematic would have a higher (less negative) intrapleural pressure than the healthy person.

c. The emphysematic would have the same intrapleural pressure as the healthy person.

d. The intrapleural pressure in the emphysematic would become positive.

e. Mr. T says: “Smoking is for fools!”

21. Breathing through a snorkel or other tube effectively increases a person’s anatomical dead space.  If a person were snorkeling and the resulting total dead space (true anatomical + snorkel) was 300 ml, what would be the effect on the alveolar ventilation rate?

a. It would increase by about 100%.

b. It would decrease by about 40%.

c. It would decrease by about 50%.

d. It would be reduced to zero.

e. It is impossible to say without additional information.

22. In comparison to oxygen and carbon dioxide partial pressures in the alveoli, partial pressures in systemic arterial blood are

a. lower for oxygen and higher for carbon dioxide.

b. lower for oxygen and lower for carbon dioxide.

c. higher for oxygen and lower for carbon dioxide.

d. higher for oxygen and higher for carbon dioxide.

e. about the same in both locations for both gases.

23. The regulation of CO₂ in the bloodstream and alveoli depends on the detection of which of the following by peripheral and central chemoreceptors?

a. CO₂

b. H⁺

c. HCO₃^-

d. H₂O

e. O₂

24. Which of the following is not associated with the gastrointestinal tract?

a. Absorption of food

b. Digestion of food

c. Excretion of waste products

d. Motility

e. All of the above are associated with the GI tract.

25.  Which of the following statements about digestive enzymes is true?

a. Amylase is activated by saliva.

b. Trypsin is activated by enterokinase.

c. Lipases are activated by bile salts.

d. Two of the above are true.

e. All of the above are true.

26. During the post-absorptive phase, the switch to fatty acid metabolism seen in most tissues is triggered directly by

a. increasing insulin levels.

b. decreasing insulin levels.

c. increasing glucagon levels.

d. decreasing glucagon levels.

e. decreasing glucose levels.

27. In healthy humans, the rate of glomerular filtration is roughly

a. 1 ml/min.

b. 10 ml/min.

c. 100 ml/min.

d. 1000 ml/min.

e. 10,000 ml/min.

28. One substance that is normally completely reabsorbed in the proximal tubule of the nephron is

a. glucose.

b. sodium.

c. urea.

d. water.

e. More than one of the above is completely reabsorbed in the proximal tubule.

29. In a person lacking an adrenal gland and thus unable to produce aldosterone, increased renin release would be able to bring about

a. an increase in sodium reabsorption but not blood pressure.

b. an increase in blood pressure but not sodium reabsorption.

c. an increase in both sodium reabsorption and blood pressure.

d. an increase in neither sodium reabsorption nor blood pressure.

e. tuberculosis.

30. Which of the following does not tend to cause a drop in arterial blood pressure?

a. a decrease in heart rate.

b. a decrease in stroke volume.

c. a decrease in blood volume.

d. a decrease in vasoconstriction.

e. All of the above tend to cause a drop in blood pressure.

31. Which of the following is a human secondary sexual characteristic that results from the presence of estrogen?

a. Appearance of the oviducts.

b. Appearance of pubic and axillary hair.

c. Development of the breasts.

d. Painted fingernails.

e. Two of the above.

32. In males, the highest levels of testosterone are found in the

a. bloodstream.

b. brain.

c. interstitial fluid.

d. prostate gland.

e. testes.

33. In males, luteinizing hormone directly promotes activity of the

a. Leydig cells.

b. Sertoli cells.

c. spermatogonia.

d. spermatocytes.

e. spermatozoa.

34. Spermatozoa develop from __________ cells and are supported by __________ cells during this process.

a. Leydig … Sertoli

b. Sertoli … Leydig

c. Leydig … spermatogonia

d. spermatogonia … Leydig

e. spermatogonia … Sertoli

35. The different components that make up semen are mixed together in which part of a male’s reproductive tract?

a. Epididymus

b. Ejaculatory duct

c. Seminal vesicle

d. Urethra

e. Vas deferens

36. In men, erection of the penis is initiated by increased activity of the ___________ and ejaculation is initiated by increased activity of the ___________.

a. parasympathetic nervous system … parasympathetic nervous system

b. parasympathetic nervous system … sympathetic nervous system

c. parasympathetic nervous system … somatic nervous system

d. sympathetic nervous system … parasympathetic nervous system

e. sympathetic nervous system … sympathetic nervous system

37. In human females, oocytes begin the process of meiosis

a. during fetal development.

b. shortly after birth.

c. at the onset of puberty.

d. immediately prior to ovulation.

e. upon fertilization.

38. During the follicular phase of the menstrual cycle, theca cells

a. are stimulated by follicle stimulating hormone.

b. produce androgens.

c. produce estrogen.

d. produce inhibin.

e. are not present.

39. In women, a significant portion of the endometrial layer of the uterus dies each month in direct response to

a. glucose insufficiency.

b. internal timing mechanisms.

c. infection by microorganisms.

d. lack of blood supply.

e. thickening of the cervical mucus.

40. During pregnancy in mammals, estrogen and progesterone are produced

a. first by the corpus luteum, then by the placenta.

b. first by the trophoblast, then by the corpus luteum.

c. by the corpus luteum throughout.

d. by the trophoblast and then the placenta.

e. Estrogen and progesterone levels are low during pregnancy

Short answer:   Write a concise answer to each of the following questions.  Your answers should fit in the spaces provided.  Each question is worth 8 points.  When appropriate, you are welcome to use a diagram in your answer, but be sure all events and processes are made clear. 

41. Provide a brief definition and an example of permeation, primary active transport and secondary active transport.  For each example, indicate a cell type or organ where it occurs.

42. The following two questions apply to myelinated axons.

a. Explain how presence of myelin increases the propagation velocity of action potentials along the axon.

b. What would be the likely effect on propagation if the myelin were continuous along the axon, with no breaks?

43. The following questions apply to synaptic transmission.

a. Briefly define spatial and temporal summation.

b. Consider a post-synaptic neuron with one excitatory and one inhibitory presynaptic neuron.  On the graph below, show the expected change in membrane potential in the postsynaptic neuron for a single excitatory postsynaptic potential, a single inhibitory postsynaptic potential, spatial summation, temporal summation, and a combination of spatial and temporal summation.  For the last three, indicate which presynaptic neuron(s) you chose to use and the number of action potentials occurring at each.

44. The following questions apply to growth hormone:

a. Diagram or describe the hormonal pathway(s) related to growth hormone.  Include the names of relevant organs or tissues, and indicate the effects of each secreted substance.

b. At what time of day is the level of growth hormone normally maximal?  At what time of life is it maximal?

45. The following questions relate to the electrical activity (i.e. action potentials) of the heart:

a. Describe the pattern of electrical activity that occurs in the heart during a normal heartbeat cycle.  You do not need to discuss the particular channels or ions involved in changing membrane potentials or the mechanical results of this activity.

b. If the heart was damaged, and there was no electrical connection between the atria and ventricles, what sort of electrical activity, if any, might you see in the ventricles?

46. The graph below shows the oxygen saturation curves for myoglobin (left curve) and hemoglobin (right curve).  Use it to answer the following questions:

a. What is the partial pressure of oxygen at which

Hemoglobin is 50% saturated?

Myoglobin is 50% saturated?

b. If the partial pressure of oxygen in the muscle is 15 torr

What percentage of oxygen does the hemoglobin unload, assuming it was saturated to start with?

How saturated will the myoglobin be?

c. If the myoglobin is 80% saturated after it equilibrates with the hemoglobin, how saturated is the hemoglobin?

d. In muscles at rest, is the myoglobin an important source of oxygen?  Why or why not?

47. Describe the hormonal control of the activity of the stomach.  You may use diagrams to show the pathways, but be certain to indicate organs or tissues involved, specific promoters and effects, etc.

48. Discuss the events in the loop of Henle.  What happens to the urine as it passes through, and why?  What purpose does the loop of Henle serve in terms of overall kidney function?

49. Explain the process by which the presence or absence of the Y chromosome leads to the development of male or female internal reproductive organs.

50. Shown below is a blank graph of hormone levels during the menstrual cycle in women.  Use it to answer a and b below.

a. Draw in the hormone levels for luteinizing hormone, estrogen and progesterone over the 28 day cycle. Be sure to label the lines.

b. Indicate when ovulation and menstruation occur.

c. During the early follicular phase, what is the source and what is the effect of inhibin?

Extra credit question – 4 points

Modern birth control pills generally consist of a dose of progesterone, resulting in blood progesterone levels approximating those seen in the luteal phase.  How might this prevent ovulation from taking place?