BIOL 260 Human Physiology, Fall 2010, Prof. Stark
First Hourly Exam, September 24, Short Answer

1. An equivalent circuit for the membrane, shown in the first lecture, plotted an exponential decrement of voltage as a function of distance. Name one of the electrical components that was shown in that model.

esistor, capacitor, battery

2. Using an expression that relates to constructive metabolic reactions and the chemical nature of the compounds, what are the testosterone-like drugs that some athletes abuse?

anabolic steroids

3. It's winter and it is cold outside, and your home heating system serves as a model of homeostasis. A furnace provides heat, "feedback" in the homeostasis model. Temperature is monitored by a thermometer. What is the other critical component in this model of homeostasis?

the set-point on the thermostat, a comparator

4. Why are the various types of insensible water loss (recall that dogs and humans were used as examples) so effective and critical in temperature regulation?

sweating or panting

5. Near the kidney is an endocrine gland that surrounds the adrenal medulla. Answer one of the following: (1) What is the name (abbreviation will suffice) of the pituitary peptide that regulates a major hormone (cortisol) from this gland? (2) What kind of chemical is this gland's hormone (cortisol)?

ACTH, steroid

6. "Hormones are not very efficient because they get diluted by the entire volume of the blood stream." Why are releasing hormones (releasing factors) from the hypothalamus different?

They travel by the portal system directly to the pituitary

7. Hypertrophy of the thyroid gland Answer one of the following: (1) results from insufficiency of what dietary substance? (2) results from insufficiency of what hormone? (3) is called (what)? (4) is referred to as endemic (why)?

iodine, thyroxine (T3 or T4), goiter, happened inland, not in coastal areas

8. "In an isotonic milieu like the blood stream, a red blood cell's shape remains unchanged." To make red blood cell ghosts, Gorter and Grendel Answer one of the following: (1) They moved the cells from an isotonic solution to what kind of solution? (2) What famous membrane transport process mediated the net influx of water into the cell?

hypotonic (distilled water), osmosis

9. In the third lecture, the importance of G protein coupled receptors (GPCR) was introduced. Where, in the ultrastructural anatomy of either a rod cell or a cell involved in phosphoinositide signaling, would you find a GPCR?

membrane disks in rod, on the plasmalemma (cell membrane

10. How much energy, delivered by ATP, is used by the GLUT-1 transporter to get glucose into the cell?


11. In contrast with the G protein coupled receptor, why is the nicotinic receptor more direct?

an ion channel is more direct than a signal transduction cascade

12. In addition to glycolipids and cholesterol, what is the major lipid constituent of the cell membrane?


13. In addition to the receptor, in receptor-mediated endocytosis, what famous protein is seen in transmission electron micrographs that gives coated pits and coated vesicles their names?


14. How much ATP would a cell use to open and close the nicotinic receptor?


15. In a simple circuit with a battery connected to the resistor, what is the slope of the line if amperes are plotted on the ordinate (Y-axis) and volts are plotted on the abscissa (X-axis)?

conductance (Siemens)

16. An exponential change in membrane voltage as a function of time is caused by what electrical property of the membrane?


17. Voltage arises from either a battery (a source of electromotive force) or (what)?

current flowing through an impedance (such as a resistor)

18. What is assumed about the total energy (chemical AND electrical) on one side of the membrane vs. on the other side of the membrane to allow Nernst equation to be derived?

the two energies are assumed to be the same

19. Suppose, with a given set of permeabilities and the standard concentrations, the Goldman equation approximated the resting potential. What would you need to change to calculate the peak of the action potential from the Goldman equation?

increase sodium permeability

20. In salutatory (leaping) conduction, the action potential jumps from where to where?

one node of Ranvier to the next

21. How is the direction that the action potential travels along the axon regulated by the refractory period of the action potential?

the refractory period keeps it from going backward (back to where it had already been)

22. For post-polio syndrome (worsening symptoms in middle age), according to a paper discussed in class, why is there (answer either) (1) a recovery after the initial infantile paralysis, or (2) the worsening symptoms in middle age?

spinal motor neurons sprout to connect to abandoned muscle fibers, these sprouts go away

23. What is the molecular mechanism for channel inactivation?

a stopper formed by amino acids near the n-terminus plugs the channel

24. For stretch of the extensor to mediate contraction of the extensor, there is a monosynaptic reflex arc. What needs to be added to this circuit for there to be a corresponding inhibition of the flexor?

an inhibitory interneuron

25. "Vagus-stuff slows the heart." Answer one of the following. (1) What major subdivision of the autonomic nervous system does vagus-stuff come from? (2) What chemical is vagus-stuff?

parasympathetic, acetylcholine

26. After calcium ions come into the synaptic terminal, what do they do to assist in vesicle release?

binds to synaptotagmin, a vesicle protein, fugure also shows calcium activating calmodulin

27. For EITHER the bacterium that causes tetanus or the bacterium that causes botulism, what is the significance of that bacterium being anaerobic?

would thrive in improperly canned goods or in deep puncture wounds

28. What molecule does malathion INHIBIT (leading the heart to stop)?


29. Chemically, what is the RELATIONSHIP of the dark pigmentation of the substantia nigra and the neurotransmitter made by the substantia nigra?

melanin and dopamine have l-DOPA as a common precursor

30. Are channels (ionotropic receptors), G protein coupled receptors (metabotropic receptors) or both used in the parasympathetic nervous system?

both, nicotinic at ganglion, muscarinic at effector

31. Which part of the autonomic nervous system utilizes a chain of connected ganglia near the spinal cord?


32. An eye care professional (for ophthalmoscope examination) [or a "beautiful woman", for cosmetic purposes] puts atropine in the eye. Answer either (1) What component of the nervous system is affected? Or (2) What is the pharmacological name of the receptor that is blocked?


33. Before they knew the chemical identity (NO = nitric oxide) they used an operational name (EDRF = endothelial derived relaxation factor). Answer either (1) What is housed in endothelial cells to make NO? or (2) What is it that was made to relax by this factor?

eNOS (endothelial Nitric Oxide Synthase), smooth muscle in arterioled to the corpus cavernosum

34. A muscle protein is deficient in Duchenne muscular dystrophy. Describe the location or function of this protein.

near the membrane, cytoskeleton or structure

35. How do you explain the shape of the length - tension curve for striated muscle?

wearke when the overlap of actin and myosin is too low or too high

36. "Power stroke causes filaments to slide; ADP is released." Answer either (1) What was released just before the ADP was released? (2) ADP was released from what molecule? Or (3) What comes in to fill the empty pocket where the ADP had been?

phosphate, myosin, ATP

37. If muscle is not "supposed to" contract (i.e. it has not been activated by an action potential), what molecule keeps myosin from binding to actin?


38. Say something (else) about the properties of the type of muscle fiber that is sometimes called fast twitch.

white meat, anaerobic, strong but not enduring

39. The action potential is carried on the sarcolemma by sodium channels. For either (1) the T(transverse)-tubules or (2) the sarcoplasmic reticulum, what channels are important?

calcium (for both)

40. You write a proposal to SLU's animal care committee for surgical research on mice. You propose to anesthetize animals with a nicotinic receptor antagonist and you justify this choice because the animal is unresponsive to a painful stimulus. The committee flatly rejects your proposal. Why?

curare or the like would paralyze the animal, not prevent pain

41. In addition to ATP interconversion with ADP plus inorganic phosphate, what other substance that interconverts between phosphorylated vs. non-phosphorylated forms is present as a small energy store in muscle?

creatine - creatine phosphate (phosphocreatine)

42. In muscle, hemoglobin would offload oxygen to myoglobin. Explain in terms of the oxyhemoglobin dissociation curve.

since the myosin curve is to the left of the hemoglobin curve, it means that myoglobin has a higher affinity for oxygen

43. What does Ca2+-calmodulin activate to make smooth muscle contract?

myosin light chain kinase (MLCK)

44. Three fatty acids bound to glycerol by a dehydration synthesis (condensation reaction). What is this molecule?

fat = triglyceride

45. Salts of cholesterol - answer either (1) Why are they useful in digestion? Or (2) Where do they come from?

emulsify fats, liver

46. Why is the liver essential in getting rid of wastes generated by getting energy from amino acids?

that is where the reaction to make urea takes place

47. After glucose is chopped into two pieces, on the way to making two molecules of pyruvate, two ATPs are generated on each of the two reactions. Why is the value given for the number of ATPs made by glycolysis less than this value (this value equals 2 x 2 = 4)?

Two ATPs must be used

48. Name something other than pyruvic acid that can feed in to make acetyl CoA at the entrance to the Kreb's cycle.

amino acids, fatty acids, ketone bodies

49. "In other words, H is split into H+ plus (what?)".

an electron

50. Upon binding insulin, the insulin receptor, an enzyme, forms a dimer. Then what does this enzyme do?

it phosphorylates itself, it phosphorylates another protein

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