BIOL 2600 Human Physiology, Fall 2016, Prof. Stark
Third Hourly Exam, Friday December 5, Short Answer

1. "Androgenic alopecia" ANSWER EITHER (1)Why is it not called a sex-linked trait? OR (2) Why was it called a sex-limited trait?

1-sex linked means on the X chromosome, 2-limited to men

2. Obviously, a steroid hormone does not bind to a response element. How does a steroid hormone affect a response element?

a steroid hormone binds a steroid hormone receptor and the receptor binds the response element

3. "Seven-year-old boys and girls behave differently, and this is probably due to circulating testosterone levels." Refute the last half of this sentence and discuss whether and how testosterone may be responsible for the difference.

there is no testosterone in boys that age but there was neonatal testosterone which had organizing effects on the brain

4. T4 (one of the thyroxine molecules) comes up to a cell's membrane in the company of a carrier protein; eventually thyroxine binds a receptor that binds a response element. Give another detail to complete the story of how it activates transcription of a gene.

turns to T3, retinoic acid binds another receptor that binds an adjacent response element

5. You are studying mitochondrial DNA in humans. Was that inherited from the father, the mother, or both?

only the mother

6. "PGI2 mediates antiplatelet aggregation." How does this information lead to a common drug treatment?

people, mostly elderly, take aspirin to prevent heart attacks

7. If you have elective surgery coming up, why would you be told to refrain from taking NSAIDS (non-steroidal anti-inflammatory drugs) a few weeks in advance?

they are anticoagulants and you would bleed

8. What is the PSA test?

for prostate specific antigen, test for prostate cancer

9. "Then it implants into the endometrium." EITHER (1) name or (2) describe what it is that implants.

blastocyst, ball of cells with inner cell mass, trophoblast and blastocyst cavity

10. In 2006, while George W. Bush was President, the famous actor Michael J. Fox, who has Parkinson's disease, came to Missouri to support McCaskill, the democrat running for senate. Answer either (1) Why would he have been so interested (in embryonic stem cell research)? or (2) Why has interest in the issue of embryonic stem cell research decreased so much since then?

such stem cells might eventually be used in treatments to replace the degenerated neurons but now embryos might not be needed since skin cells can be made into pluripotent stem cells

11. A sperm is just about to fertilize an "egg" but it has not quite yet. Answer either (1) What is this prefertilization egg called? OR (2) Where in the process of meiosis, is this "egg?"

secondary oocyte has finished first meiotic division but not second

12. Many women want to bear their children before the age of 40 because of an increased likelihood of (what is the most famous disorder here)?

trisomy-21 (Downs syndrome)

13. Under the influence of a gene on the Y chromosome, "indifferent gonads" turn into a structure that produces Mullerian Inhibiting Factor (MIF) plus (what?).

the testes also produce testosterone

14. A neutrophil arrives at the site of the injury. Answer either (1) What does it do when it gets there? or (2) What do they call the process of its attraction to move to that site?

phagocytosis, chemotaxis

15. Macrophage: ANSWER EITHER (1) Why does the word end in "phage?" OR (2) What type of white blood cell is it derived from?

1-it eats (phagocytoses) bacteria, 2-monocyte

16. Why, in the early days of AIDS, were hemopheliacs particularly susceptible?

blood banks were not safe, and clotting factor was produced from multiple donors

17. A naïve B cell is exposed to an antigen. Describe the constituents of the clone of cells that develops from this cell.

plasma cells make antibody, memory cells preserve the information

18. Why would blood cells be expected to agglutinate for a type B transfusion into a type A recipient?

the Y shaped antibody molecule can hold two red blood cells together.

19. In 1796, Jenner exposed people to cowpox to give them immunity to smallpox. What did Lady Montague do 3/4 of a century earlier to make people immune to smallpox?

she exposed them to smallpox itself

20. Independently, you develop two different antibodies to the same antigen molecule. I contend that there is a vanishingly low possibility that these antibodies are the same. Why would I say such a thing?

they are specific to any 5-15 amino acid subset of the entire protein

21. In the news: Why do you think they gave a blood product from an ebola survivor to an ebola patient?

passive immunity from gamma globulin

22. "Class-2 MHC molecules are expressed on macrophages and B cells." By contrast, where are class1 MHC molecules expressed?

lots of cells

23. "The Pacinian corpuscle has rapid adaptation." How does that relate to its particular function?

that means it responds to vibration and is useful for active feeling (moving your fingertips) touch

24. In the 1800's, Broca delineated a brain area critical for speech. How did he do this?

after death, looked at brains of patients whose speech had been damaged by stroke

25. "An enzyme at the site of injury converts a precursor into bradykinin." What does this tell us about the somatosensory system?

nociceptors are actually chemoreceptors

26. Lemniscal system. ANSWER EITHER (1) Where is the tract in the spinal cord? (2) Which side of the spinal cord is it in (relative to where the receptor is)? OR (3) What is the function of this submodality?

1-dorsal columns, 2-same side (ipsilateral), 3-fine touch (as opposed to pain)

27. You all have the protein coded for by the gene involved in Huntington's disease. And yet you do not have Huntington's disease (hopefully). What is the difference for people who do, in fact, have Huntington's disease?

they have more CAG repeats (coding for glutamine)

28. 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)

29. Why would a lesion (an injury) halfway across the spinal cord cause an ipsilateral loss of fine touch below the injury but a contralateral loss of pain below the injury?

the decussation in the lemniscal system is in the medulla while the decussation in the anterolateral system is at the site of entry to the spinal cord

30. Where is the first synapse in the taste projection?

at the base of the receptor cell

31. "cAMP acts as a ligand in olfactory receptors." Say something to elaborate this point.

the G protein cascade has cAMP as the "second messenger" and cAMP opens the channel in the cell membrane, and so this ligand acts on the channel from inside the cell

32. The chemoreceptive part of the olfactory cell is in the nasal cavity. Where is the synapse?

in the olfactory bulb (first cranial nerve) of the brain

33. There are 3 semicircular canals plus (name one other component) in the vestibular system.

utricle, saccule

34. The endolymph fluid in the cochlear duct (scala media which bathes the stereocilia) is unusual (for an extracellular fluid) in that it contains a high concentration of (what?)


35. In what way is the very low number (0.0002 dynes per square centimeter) fundamental in human hearing?

the standard pressure (denominator) in the definition of dB

36. In terms of either what is in the membrane OR how an extracellular protein assists, say how transduction in hair cells works.

a mechanoreceptive channel, tip links

37. One tuning fork clearly had a higher pitch than the other. How did you know that they differed by only a few Hz?

you could hear just a few beats per second when listening to both simultaneously

38. There are four or five synapses in the auditory pathway. Where are the terminals of the cells in the thalamus (that receive synaptic input from "further down, the inferior colliculus)?

on the auditory part of the cerebral cortex

39. If the ciliary muscle is contracted, what happens to... (answer one of these) (1) the suspensory ligaments, or (2) the shape of the lens, or (3) your eyesight?

they become slack, it gets rounder, for near vision

40. In an eye exam, they check your eye pressure. If it is too high, answer either (1) Which cells die? OR (2) Which portion of the eye does not drain properly?

ganglion cells, aqueous humor (anterior chamber)

41. Fixating on an X with your right eye, there is a place off to the right where you are blind. Reconcile that fun "blind spot" demonstration with my statement that the optic nerve exits the eye on the nasal side.

off to the right means on the temporal visual field, and, because the image is inverted, that is the nasal retinal field

42. "My optic bench features a mercury arc lamp and a grating monochromator." How do I change the intensity of the visual stimulus?

put in neutral density filters where each 0.3 log units cuts the light in half

43. Which portion of the nervous system connects to the iris to mediate the constriction of the pupil elicited by a light stimulus?

parasympathetic, occulomotor nerve (#3), from ciliary ganglion

44. I suggested that a gene duplication on the X chromosome could be used to explain how the superfamily of G protein coupled receptors evolved. Which two proteins are made by the two duplicated X chromosomal genes I am referring to?

the genes for red- and green-absorbing rhodopsins

45. Other than serving as the "black paint" that keeps light from reflecting around the eye, state another function of the retinal pigment epithelium.

phagocytose shed rod disks, chemical reactions to replenish 11-cis-retinal

46. Why would we use the term "tunnel vision" for the blindness in retinitis pigmentosa?

rods in a circle around the point of fixation degenerate

47. Why are you unable to see ultraviolet light (while I can)?

the lens blocks UV, I had a lens removed

48. In phototransduction, the heterotrimeric G protein's alpha subunit activates an enzyme. For EITHER Drosophila OR humans, what is that enzyme?

phospholipase C or cGMP" PDE

49. "Vitamin A is the chromophore of rhodopsin." We get this vitamin A from what dietary precursor?

carotenoids like beta carotene

50. Say something about the garbage that accumulates in cells of the aging human eye.

called lipofuscin, autofluoresces yellow, in retinal pigment epithelium cells, from shed photoreceptor tips

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last updated Nov. 28, 2016