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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?
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
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)?
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)?
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)
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
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
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
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?
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
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
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
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?)".
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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