BIOL 2600 Human Physiology, Fall 2016, Prof. Stark
First Hourly Exam, Friday October 28, Short Answer

1. Why would the vitreous of the eye become less transparent after long-term diabetes.

leakage from blood vessels created by angiogenesis

2. Suppose there were a new substance, a potential drug or poison, that depolarized all the beta cells in your islets of Langerhans. What do you expect would happen if you tested this substance on an animal?

more insulin release, lower blood glucose, maybe coma

3. Cyclic AMP binds to an inhibitory subunit. When a cell is activated by glucagon, what enzyme gets activated as a result?

protein kinase (PKA=A-kinase)

4. There are two peptides in the insulin molecule. ANSWER EITHER (1) What holds the two chains together? OR (2) How did there come to be two chains from the pro-hormone?

1-disulfide bonds between the cysteines, 2- a chunk was chopped out of the middle

5. Why do the textbook artists color the pulmonary arteries blue?

they carry blood low in oxygen and high in carbon dioxide

6. There are many layers in an artery. Only one of these layers of cells is present in a capillary. What is this type of cell called?

endothelial cell

7. Chordae tendineae, answer either (1) What do they connect to? OR (2) Why are they important?

from ventricular papillary muscles to tricuspid and bicuspid (AV) valves, to reinforce valves so that ventricular pressure does not blow them out into the atria

8. "Most of the blood pressure is lost by the time blood reaches the small veins (venules), after traversing the capillaries." Then what propels blood back toward the heart through veins?

valves prevent back flow, striated muscles squeeze the veins

9. The first few moments of ventricular contraction fail to move blood into the arteries. Why?

isovolumetric contraction is because semilunars remain closed until ventricular pressure is higher than arterial pressure

10. In the atria, all that was needed to propagate the electrical signal was the connections from one myocardial cell to the next. For the ventricles, why was it important to have the added feature for propagation (bundle of His and bundle branches)?

to start the contraction at the "apex" (bottom), to send the action potential quickly

11. There is a family of curves for different amounts of sympathetic nerve stimulation where stroke volume in ml is plotted as a function of ventricular end-diastolic volume in ml. Answer either (1) What is this called? (2) In what way does this distinguish the properties of cardiac vs striated muscle as a function of length? or (3) What effect does sympathetic stimulation have on these curves?

Frank-Starling law, cardiac muscle does not get weaker as a function of length, it moves them up and to the left

12. Describe the voltage as a function of time to explain the pacemaker action of the cells in the SA node.

during diastole, the voltage depolarizes from its most hyperpolarized level down to the threshold for the action potential

13. Congestive heart failure ANSWER EITHER (1) would be diagnosed if there were a low number on what reading? OR (2) could be treated by what drug (EITHER what is it called OR what does it do)?

ejection fraction (amount of ventricular emptying) would be low, say less than 1/2, on echocardiogram, treated with sodium pump inhibitor (digitalis toxin) that increases calcium in the heart increasing contractility

14. Three "leads" describe 3 different ways both wrists might be fed in for measuring the ECG. Why might different people have differences in how the ECG looks with the 3 leads?

orientation of heart (axis) can differ, abnormalities like murmurs might create an asymmetry in heart muscle

15. What would have to happen to the shape of the action potential of a ventricular myocardial cell to compensate for the increased heart rate that accompanies heavy exercise?

the long duration action potential would get shorter

16. Re-entry of excitation - Why might myocardial cells have an action potential that occurs too early, i.e. before the next heart beat that originates from the SA node?

an action potential going from cell to cell around an area with non-conducting tissue resulting from damage would arrive at cells that are no no longer refractory sooner than the next SA trigger would arrive

17. Regarding Eindhoven's triangle: Why doesn't the distance from the wrists and ankle to the heart interfere with recording the ECG?

the huge extracellular space has virtually no resistance

18. Why is asbestos more of a problem for smokers?

their cilia are paralyzed and cannot remove asbestos by the mucus elevator

19. Epinephrine would help a person having an asthma attack. What completely different approach could be used, in this case to control inflammation?

antileukotriene like Singulaire

20. The partial pressure of oxygen in alveoli is much lower than in the inspired air. Why?

water and carbon dioxide, virtually zero in inspired air, is much higher in alveoli, also not all the air exchanges

21. "You have less surface area for gas exchange." What disorder am I discussing here?


22. Give either the approximate number or the value relative to atmospheric pressure of the intraplural space during inhalation.

book says 754 mm Hg, the point is that it is slightly less than lungs which are slightly less than atmospheric

23. The partial pressure of carbon dioxide in the pulmonary vein is 40 mm Hg. What is the partial pressure of carbon dioxide in the systemic arteries?

duh! there was no gas exchange between the two

24. Why do chemoreceptors in the medulla react more to high carbon dioxide than those of the carotid and aortic bodies?

there are no buffers in the cerebrospinal fluid

25. Why do premature infants have trouble breathing?

type 2 alveolar cells mature around the time of birth and without surfactant, the surface tension of water tends to close the alveoli

26. Why is it advantageous for some animals to use uric acid rather than urea in their excretory systems?

less water is lost

27. Where (answer either cellular location or molecule) is energy used to resorb glucose across a cell in the kidney tubule?

basolateral surface, sodium pump

28. In addition to fenestrated endothelium, what structural specialization contributes to glomerular filtration?

pedicels of podocytes make a sieve

29. The vasa recta (peritubular capillaries) are "wired" in series with what capillary tuft?


30. People with gout have high levels of what substance?

uric acid

31. Salt appetite, ANSWER EITHER (1) A hormone from (what endocrine gland?) is associated with salt appetite? (2) That hormone affects (what specific part of the nephron?)? OR (3) What is the name of this hormone?

1-adrenal cortex, 2-ascending loop of Henle. 3-aldosterone

32. ADH (antiduretic hormone, alias vasopressin). Answer (1) What channels are regulated by ADH? or (2) Where (specifically) does ADH have its effects?

water channels (aquaporins), collecting duct

33. We discussed many different blood vessels in the nephron. Which regulates the angiotensin system?

afferent arteriole

34. What, if any, type of polymer would be broken into monomers if given enough time in the presence of salivary amylase?


35. Chief cells: answer EITHER (1) What is the name of the zymogen (precursor) in the granules of these cells. (2) Acid secreted (from what cell?) helps to form the active enzyme from this precursor?

pepsinogen, parietal

36. In a healthy person, urobilinogen is eliminated via the urine and (how else?).

in the feces

37. What is the source of material that neutralizes acidity as stomach contents move to the small intestine?

bicarbonate comes from the pancreas

38. "Therefore, I suggest that you keep a few bottles of Gatorade around the house, because you are not going to want to run to the store to buy it." This recommendation came after talking about a cAMP cascade's function in the small intestine. Say something else (fill in something between cAMP and my recommendation) about this story.

cholera toxin disrupts water resorption, an electrolectrolyte coctail with glucose facilitates rehydration when dehydrated

39. Amino acids stimulate G cells to release gastrin. State one of the secretions that result from this.

one cell (ECL cell) puts out histamine causing parietal cell to put out HCl

40. Facilitated by bile salts and catalyzed by lipase, triglyceride plus two water molecules is converted into (what three molecules?) in the intestinal lumen?

a monoglyceride plus two fatty acids

41. Regarding oxytocin and ADH, the portal system connecting the hypothalamus to the pituitary is not utilized. Elaborate.

neurosecretions from axon terminals in the posterior pituitary, cell bodies in the hypothalamus

42. "In women, oxytocin affects smooth muscle in the mammary gland for the ejection of milk." Where else, or in what other circumstances, do women have smooth muscle controlled by oxytocin?

in the uterus for labor and delivery

43. "The follicle includes a 'rind' of cells and the egg enclosed in this rind." What does this rind do?

secretes estrogen

44. Fertility is blocked by the pill...answer one of these: (1) How is fertility blocked? or (2) Why would there still be menstruation every month?

no ovulation (b/c no LH or FSH [b/c of steroids in the pill]), steroids build up endometrium, then lack of steroids let it break down

45. In addition to initiating the formation of the corpus luteum, a burst of LH does what?

leads to ovulation

46. After implantation, what happens to the progesterone level?

maintained (but now by HCG instead of LH)

47. Vitamin D has effects more similar to (which?) calcitonin or parathormone. Explain (justify).

increase blood calcium like parathormone

48. Cretinism is from shortage of what hormone at what phase in life?

thyroxine neonatally

49. Sunlight on the skin is involved in the activation of what hormone?

vitamin D, specifically conversion of 7-Dehydrocholesterol to vitamin D3

50. If you did not have sufficient glucocorticoid secretion ANSWER EITHER (1) What is this disease called? OR (2) Why might a person with this disease, like President Kennedy, look like he has a nice sun tan?

addison's disease, there is too much ACTH from decreased feedback and ACTH is similar to melanocyte stimulating hormone

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last updated Oct 21, 2016