BIOL 260 Human Physiology, Fall 2010, Prof. Stark
Second Hourly Exam, October 27, Short Answer

1. Insulin is made from a prohormone. State one of the things that are done to make insulin from this prohormone.

A peptide fragment is removed from between the 2 that are part of insulin and these are linked by 2 disulfide bonds

2. The long term health of a person with type 1 diabetes is best if the right amount of insulin is given, keeping the person's blood sugar just above the level that would result in coma. What would happen if less than that amount of insulin were injected one time?

the blood glucose would not be quite as low, that's all

3. Answer either (1) for gluconeogenesis, where did the glucose come from? Or (2) for ketogenesis, where did the ketone bodies come from?

1 from amino acids, 2 from triglycerides

4. 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

5. For the atrial beat, answer either (1) Why does it contribute only minimally to ventricular filling? Or (2) What would keep the blood from flowing backward into the veins coming into the atria?

1 blood goes from atria to ventricles even before the beat, 2 nothing except those valves that are in veins

6. 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 afterial pressure

7. You feel chest pain so you take nitroglycerine. How did this save you from a heart attack?

relaxation of smooth muscle in coronary arteries would alleviate the block (that likely resulted from a thrombus or an embolism in an artery already partially occluded from atherosclerosis)

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

they carry blood low in oxygen and high in carbon dioxide

9. Why can you hear the brachial artery below the blood pressure cuff when the cuff pressure is between the systolic and diastolic levels?

Korotkoff sounds are when blood flow is turbulent from partly closed artery

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. 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 asymetry in heart muscle

12. What would the sympathetic nervous system do to the shape of a myocardial cell's action potential?

shorten that prolonged spike

13. A person drops over and has no pulse. To keep him or her alive until medical equipment and personnel arrive, (answer either) (1) What is the name of the procedure you would perform? Or (2) How would this keep the victim alive?

CPR, it keeps the brain alive

14. "Re-entry of excitation:" After recovering from a heart attack, why might some myocardial cells be excitable (no longer refractory), and be triggered to fire, before the appropriate time (that appropriate time being the time synchronized from the SA and AV nodes)?

a pathway of myocardial cells around the scar might be long

15. Why was a reminder of the process of receptor-mediated endocytosis by clathrin-coated pits relevant in the context of heart attacks?

LDL is removed by that process

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

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

17. Pick one: (1) A drug that specifically affects beta-2 adrenergic receptors (terbutaline), or (2) a drug that blocks leukotriene action (Singulair). What is the specific action that would help in asthma?

1 open airways by mimicing adrenalin or the sympathetic nervous system, 2 decrease inflammation

18. The partial pressure for oxygen in the atmosphere is atmospheric pressure times the fraction of the atmosphere that is oxygen. What are the major reasons that the partial pressure for oxygen in the alveoli is much lower?

there are higher proportions of water vapor and carbon dioxide

19. You have a subject and a spirometer. What value, a portion of total lung capacity, cannot be obtained?

residual volume

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

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

21. Why does a premature baby have trouble breathing?

type 2 alveolar cells mature late and without surfactant, water pressure impedes alveolar opening

22. Where, other than the medulla oblongata, are chemoreceptors located that feed by nerves to the respiratory control centers?

aortic and carotid bodies

23. Relative to curve where % oxygen saturation is plotted as a function of partial pressure for oxygen for adult hemoglobin, how would you place the curve for fetal hemoglobin?

fetal oxyhemoglobin dissociation curve is to the left of the adult

24. Why does chloride come out of red blood cells in the lungs?

so bicarbonate can come in for the generation of carbon dioxide to be exhaled

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

less water is lost

26. "Upwelling of nutrients off the coast of Peru." Answer either (1) What ocean current helps with this? Or (2) What is the climate abnormality that disrupts current and upwelling?

Humboldt current, El Nino

27. Non-steroidal anti-inflammatory drugs (NSAIDS) inhibit the formation of what mediator of inflammation?


28. Peritubular capillaries (the vasa recta) form part of the kidney's portal system. Where is the other capillary bed?

the glomerulus

29. A basement lamina separates two components of the glomerular sieve. Name one of these two cellular components.

podocyte's foot processes and fenestrated capillary

30. Facilitated diffusion for glucose takes place on the basolateral surface of a proximal tubule cell. For EITHER of the other two essential components of glucose transport in this cell type, give BOTH the membrane transporter PLUS the location of the membrane.

cotransport-apical, sodium pump-basolateral

31. What function does it serve to have salt but not water transport in the ascending limb from the loop of Henle?

to increase the osmolarity of the interstitial fluid

32. Elimination of what hormone from your body would make you crave salt?


33. ACE=angiotensin converting enzyme: Answer EITHER (1) What hormone from the kidney activates ACE? Or (2) For what disorder might you want to inhibit ACE?

renin, hypertension

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 the precursor?

pepsinogen, parietal

36. A SEVERE stomach disorder was once attributed to excess stomach acid. A further elucidation of this disorder was worthy of the 2005 Nobel prize in medicine (awarded to Marshall and Warren). Answer either (1) What disorder? Or (2) What was the cause of the disorder they discovered?

ulcer, bacterium (Helicobacter pylori)

37. Enzyme activity as a function of pH: describe the graphs for pepsin vs. salivary amylase.

peaks are at 2 and 7 respectively

38. Say something about how or where trypsin is activated.

trypsin is activated in the intestinal lumen by chopping a fragment from the zymogen under the influence of enderokinase on the brush border (or by trypsin that has already been activated)

39. In reference to lipase in the intestinal lumen, tell me either (1) What is the source of lipase? Or (2) What are the products when it acts on a triglyceride?

pancreas, monoglyceride plus two fatty acids

40. Why is the function of the hepatic portal vein so important?

It delivers materials absorbed from the intestines to the liver for detoxification

41. 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

42. Using the correct terminology about the drug's affect on appetite (hunger), tell me about amphetamine.

it is anorexogenid (it causes anorexia)

43. In its effects in the mammary gland and uterus, what kind of cell is affected by oxytocin?

smooth muscle

44. If a body builder abuses growth hormone, what is likely to happen to his or her bones?

they will grow in thickness

45. What is a general term that takes into account the trophic influence for both males and females of FSH, LH, ICSH and HCG?


46. What happens if there is too little thyroid hormone during an infant's development?

brain development is compromised (cretinism)

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

secretes estrogen

48. "There is a surge of LH." Answer one (1) Where did this LH come from? (2) What kind of molecule is that LH? Or (3) Name one of the effects that has on the ovary.

pituitary, peptide, convert flooicle to corpus luteum, cause ovulation

49. Would the endometrium build up and break down in women who are taking the pill? (Include in your answer why or why not.)

yes, steroids would cause build up and duds (without steroids) would allow break down

50. What happens to the corpus luteum after implantation?

It is maintained and continues to secrete progesterone under the influence of HCG

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