BIOL 260 Human Physiology, Fall 2010, Prof. Stark

Final Exam, December 8, Short Answer


1. How come there is heat available to allow you to regulate your body temperature at 98.6 o F?


catabolism is only about 40 % effective in useful work, the ³waste² is heat that can be used


2. ³The nucleus orchestrates the cellıs functions by [doing what?] at the level of the ribosomes?


(via mRNA) translation of proteins


3. What would vasoconstriction do to help to regulate body temperature?


Decrease heat loss


4. Used as an example of homeostasis, thyroxine was shown to have what effect on the anterior pituitary?


³inhibits responsiveness to TRH² translates to feeds back to decrease release of TSH


5. ³IP3 is a ligand for a calcium channel.² Answer one of the following: (1) Where is this Ca2+ channel? (2) Where was the precursor of IP3 (the molecule from which IP3was formed by the action of PLC [phospholipase C])?


(1) on a smooth endoplasmic reticulum, a calcium sequestering cistern [lucky you, I gave you the answer in question #13 for free] (2) PIP2 is a membrane phospholipid


6. ³Vitamin A deprivation decreases the number of bumps seen in fruit fly photoreceptor membranes (transmission electron microscopy of freeze fracture replicas).² These bumps are a visualization of what molecule?




7. Note that ATP is not used in a channel like the nicotinic receptor that can be closed or, when opened, passes K+ and Na+ (causing depolarization). Where, if at all, is ATP utilized in generating membrane potentials based on K+ and Na+?


Working in the background, the Na+ - K+ ATPase establishes Na+ and K+ gradients


8. E=IR. Answer one of these. (1) What are the units for E? (2) What are the units for I? (3) What are the units for R? (4) What is this relationship called?


(1) Volts (2) Amps (3) Ohms (4) Ohmıs law


9. After the equilibrium assumption in the derivation of the Nernst equation, the chemical gradient is shown to be equal and opposite to (what)?


Voltage (electrical gradient)


10. ³For passive spread of voltage along the axon, the time constant is independent of the axon radius.² Then how come large invertebrate axons are faster than small ones?


The space constant varies with the square root of the radius


11. Oh sure, myelin ought to be a good insulator on the basis of the many layers of resistance, but what about capacitance?


Since capacitors in series add reciprocally, the many layers decrease capacitance, also making myelin a good insulator


12. If multiple sclerosis (MS) is caused by immunity to a protein in myelin, how come everybody does not have MS?


Autoimmunity is from the immune surveillance ³seeing² a protein that is sequestered from surveillance in most people


13. What is different in the gating of Ca2+ channels involved in release of synaptic vesicles vs. when IP3 interacts with the smooth endoplasmic reticulum that acts as a Ca2+-sequestering cistern?


The voltage of the action potential gates the channels for vesicle release, whereas the inositol trisphosphate channel is a ligand-gated channel


14. ³Muscarine is an agonist for a G protein coupled receptor for acetylcholine.² Name the famous agonist for the acetylcholine receptor that is a channel.




15. When norepinephrine is the ³first messenger² activating the G protein coupled receptor, cyclic AMP has been called the ³second messenger.² Answer either: (1) What is the precursor of cAMP? Or (2) What is the enzyme that turned that precursor to cAMP?


ATP, adenylate cyclase


16. What is the interesting parallel in the actions of Viagra and caffeine?


They both inhibit a phosphodiesterase, Viagra inhibits cGMP breakdown and caffeine inhibits cAMP breakdown


17. What difference, if any, is there between the neurotransmitter used to activate beta-1 adrenergic receptors vs. beta-2 adrenergic receptors?


No difference, norepinephrine for both


18. In the middle of the sarcomereıs A band is a lighter area (H band). Why is it lighter than the rest of the A band.


There is myosin but no actin


19. What important protein of each sarcomere is missing from the following list? Titin, myosin, tropomyosin, actin.




20. In heavy exercise, and heavy exercise can only be maintained for a short duration, glucose, delivered from blood plasma, and glycogen, resident in muscle cells, are the predominant energy sources. What is the predominant energy source (and where does it come from?) for light exercise for long duration?


Free fatty acids from plasma


21. Because cardiac output limits oxygen delivery to muscleŠ (Say something about how the utilization of glucose by muscle is altered.)


this is why God gave humans anaerobic glycolysis


22. ³Nuclear chain fibers contribute to the reflex.² Answer either (1) How? Or (2) Via what type of neuron from the spinal cord?


By presetting the stretch on stretch receptors, gamma fibers


23. ³The axon ends in the axon terminal where the neuron makes a synapse onto the next cell.² Describe an exception to this geometry for an autonomic neuron affecting smooth muscle.


Instead of an axon terminal, there are numerous varicosities


24. ³Disulfide bonds hold together some places along the length of a protein.² What level of organization is this?




25. Glucose is taken up into a liver cell. During an ordinary day in your life, when does this happen?


After meals


26. For cAMP, answer either (1) How, molecularly, does it activate protein kinase? Or (2) How could you persuade that cAMP to stick around a little longer?


(1) binds to (and removes) inhibitory subunits (2) block its breakdown with caffeine


27. Suppose there were a new substance, a potential drug or poison, that increased the cytoplasmic Ca2+ level in the beta cells in your islets of Langerhans. What do you expect would happen if you tested this substance on an animal?


More insulin vesicles released, possibly leading to coma


28. Approximately what is the pressure in the left ventricle when the semilunar valve (to the aorta) opens?


At that moment it should equal diastolic pressure


29. Opening up the arteriovenous anastomoses would do what to blood flow in the capillary loops in the dermis?


It would bypass (therefore decrease) blood flow in the capillary loops of the dermis


30. The parasympathetic output to the heart affects both the SA and the AV nodes. What affect in addition to these two does the sympathetic output to he heart have?


It affects contractility in the myocardium in addition to affecting rate via the nodes


31. How would the sympathetic nervous system affect the shape of a series of action potentials recorded from a cell in the SA node?


Diastolic depolarization (pacemaker potential) would reach threshold faster (and the rate would go up)


32. Why is the expression ³referred pain² sometimes applied to the pain experienced during a heart attack?


Pain from viscera and heart is projected onto the somatosensory map, thus for the heart, classic symptoms of shooting pain in left shoulder and neck especially in men


33. Why do people with emphysema need to breathe more?


With fewer alveoli, there is less area for gas exchaqnge


34. In what way is the coating of water in the alveoli different with vs. without surfactant?


With-it has lower surface tension than without


35. For cystic fibrosis, (answer one of these) (1) A gene, mutated in cystic fibrosis, codes for what? (2) What are the symptoms? Or (3) How does the parent treat those symptoms on a daily basis?


CFTR, a chloride channel


36. What happens to ventilation when pH goes down in the cerebrospinal fluid (CSF) of the medulla oblongata at the confluence of integrating inputs from aortic and carotid bodies, the pneumotaxic center and the apneustic center?


More acidity implies more carbon dioxide, so you breathe harder


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


Uric acid


38. Many people enjoy an electrolyte replacement beverage such as Gatorade if they perspire a lot. They do not like such drinks if they pee a lot. Why the difference?


More salt is lost in sweat than in urine


39. For ADH (antidiuretic hormone = vasopressin), answer one of these (1) What does it do to the membrane to facilitate transport? Or (2) Where, in the kidney, does it have its effect?


Adds aquaporins (water channels) in the collecting duct


40. WARFarin: Answer EITHER (1) Why is a substance like this effective for poisoning rats when, otherwise, it is difficult to poison a rat? Or (2) Why might it be given, in lower than poisonous doses, to a person?


They will avoid the taste of something that makes them sick but the delayed anticoagulant action is not noticed (until it is too late), anticoagulants decrease the chance of a thrombus or an embolism


41. Absorption of what important substance from the gut is disrupted by cholera toxin?




42. Why is it useful to have a lot of mitosis in the crypts of intestinal villi?


Intestinal cells digest themselves and need to be replaced


43. ³In digestion, we break proteins down into amino acids for absorption.² How would you modify that statement for the apical membrane of intestinal epithelial cells.


Dipeptides and tripeptides also cross this membrane


44. Why is the function of the microsomal fraction of hepatocytes so important?


Detoxify drugs, alcohol, etc


45. What kind of molecules, biochemically, are the hormones released by the posterior pituitary?




46. One capillary net is in the infundibulum and receives its hormones as neurosecretions from the paraventricular and preoptic areas of the hypothalamus. Obviously, I am describing a portal system. Where is the second capillary net?


Anterior pituitary


47. Why did former President Kennedy seem to have a nice sun tan?


With low cortisol from Addisonıs disease, little feedback resulted in too much ACTH which overlaps with MSH (melanocyte SH)


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


no b/c steroids of the pill inhibit FSH and LH which would build follicle into corpus luteum


49. A gland in the neck puts out a hormone that causes the dissolution of CaPO4 from bone to increase blood calcium. Name EITHER (1) the gland, (2) the hormone, or (3) the cell that mediates dissolution of the bone.


Parathyroid, parathyroid hormone, osteoclast


50. What is the hormone from the adrenal medulla?


Epinephrine (adrenalin)


51. Why would a transdermal patch be better than oral administration for estrogen replacement therapy?


Less conversion by liver


52. A steroid hormone binds to a receptor that is located in the cytoplasm of the cell. State one of the next things that happens with this hormone-receptor complex.


Goes to the nucleus and binds response element, a place in the promoter on DNA


53. What does ³20:4² signify when referring to the precursor of prostaglandin?


Arachidonic acid, a fairly long chain fatty acid, is 20 carbons long and has 4 double bonds


54. What is the function of a signal known as ³inhibin?²


feedback on FSHıs effectiveness on seminiferous tubules


55. Answer EITHER: ³Viagra inhibits the enzyme (what enzyme?) that breaks down (what?) as a medication for erectile dysfunction.²


Phosphodiesterase, cGMP


56. How much before or after the sperm meets the egg is meiosis completed for the egg?


Pretty much simultaneous (just a moment before) fertilization


57.  What would have happened to a person who did not have Mullerian Inhibiting Factor (MIF)?


Primordial ³plumbing² would become uterus and uterine tubules


58. It was argued that Rasputin may, in fact, have been able to help Czarevitch Alexis. How?


The hemopheliacıs bleeding might might have been decreased by getting vasoconstriction by controlling his sympathetic output to arterioles


59. What type of cell do monocytes (mononuclear cells) become after they are outside the circulatory system?




60. What does type O blood have or lack that permits type O individuals to be universal donors?


Type O red blood cells lack antigens, so that blood can be transfued into any recipient regardless of whether that person has antibodies


61. A molecule on the surface of a B cell was shown in one diagram as Y-shaped; it was called a ³B cell receptor² and it was shown as binding to an antigen on a pathogen (probably a bacterium). What was this molecule? Be as specific as you can.




62. How does class-2 MHC assist a macrophage ³tell² a B cell what antigens to ³worry² about?


MHC-2 and CD4 corepressor are involved in the communication from the antigen presenting macrophage to the T cell


63. A neurosurgeon applies a gentle electrical stimulus to the postcentral gyrus of an awake patient under local anesthesia. What does the subject say (or do)?


(s)he feels something on a certain area of the body


64. A somatosensory cell has a synapse in the dorsal (and lateral) part of the spinal cord. Where does the postsynaptic cell make its synapse in the brain?


Thalamus (spino-thalamic division of the somatosensory input)


65. The basal nuclei collect information from all over the brain and send it to (where?) to achieve better coordination of motor movements.


Motor cortex (via thalamus)


66. Some taste cells depolarize in response to the appropriate chemical stimulation. What must happen, downstream of depolarization, for vesicles of neurotransmitter to be released?


Calcium ions must come in through calcium channels


67. Contrast how cAMP gates a cation channel in an olfactory receptor cell with the way acetylcholine gates the nicotinic receptor.


cAMP from inside the cell, Ach from outside, both channels are ligand gated


68. Stereocilia in human audition are bent as the basilar ³membrane² moves relative to what other ³membrane?²




69. Name one of the two differences (between sound in one ear vs sound in the other ear) that contribute to auditory localization in the human.


Time of arrival (because of distance and the speed of sound) and intensity (because of the sound ³shadow² of the head)


70. State a major difference between retinitis pigmentosa and age related macular degeneration.


Rods (as young adult) ve cones (in elderly)


71. State one of the three fundamental functions of the retinal pigment epithelium.


Black ³paint,² retinoid metabolism, phagocytosis of distal tips of rods that are shed daily


72. The aldehyde of vitamin A (retinal, formerly called retinene) is hit by light. What happens to it?


It bends [isomerizes] (it relaxes from 11-cis to all trans)


73. Under what circumstances is there lots of cGMP to open the channels in the rod outer segment?


In the dark


74. In Prof. Starkıs research seminar, a recent suggestion was that clathrin was associated in an ³import² pathway (rough endoplasmic reticulum to Golgi apparatus to the organelle where rhodopsin mediates vision). More traditionally, for many decades, clathrin was seen (in what structure?) in the transmission electron microscope.


Coated pits, coated vesicles, endocytitic structures, clearance


75. In what context is vitamin A relevant to a G protein coupled receptor?


The aldehyde of vitamin A is the chromophore that attaches to the protein rhodopsin (which is a G protein coupled receptor)