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Biology 347 - General Physiology Lab - Stark and Kumar - Fall 2004
Midterm - 10/7/04 (each question is 1 point unless specified) 50 points
1. What important factors determine the strength of contraction of a muscle?
The size of the motor unit being stimulated and the number of motor units
2. What do you fill micropipette electrodes with?
Concentrated NaCl or KCl
3. When a motor neuron fires, how many muscle cells are stimulated?
All of the muscle cells that form junctions with that one neuron. (The number
of muscle cells in a motor unit can vary.)
4. How do you know whether a mouse is sufficiently anesthetized?
If it does not react to a foot pinch
5. Suppose you were trying to record an ECG (EKG, electrocardiogram). For
the purposes of this question, you need to know: (1) there are 5 components,
called P, Q, R, S, and T, (2) all 5 occur during each heart beat, (3) resting
pulse is typically 72 beats per minute, and (4) from the beginning of the
P wave to the end of the T wave might be typically 1/3 of a second. The
amplifier of the polygraph is set to direct coupled. Your subject cannot
sit still, and the trace keeps going off scale top and bottom every 5 or
10 seconds. What should you do electronically to get the line to stay on
To filter out slow "drift" and still pick up fast changes, use
a high pass filter. Or change the scale (lower sensitivity) and that would
work, though the EKG would be small.
6. What is the general function of motor units that contain only a few muscle
Precise muscle movements. (Extraocular muscles would be an example.)
7. Why does too much insulin lead to shock?
Insulin dependent tissues, like muscle, would pull too much glucose out
of the blood, leaving too little for the brain which depends on glucose.
8. What two factors affect the strength and degree of muscle movement?
The number of motor units firing and the number of muscle cells per motor
9. What are the interconnecting tubules of Ca2+-containing endoplasmic reticulum
that surround each myofibril?
10. Which part of the contractile apparatus that contains both thin and
11. When, during an action potential, is potassium permeability the greatest?
12. In neurons, which direction is the chemical force of sodium? Why?
The direction is into the cell because it has a higher concentration outside
the cell and diffuses down its concentration gradient.
13. What actually insulates myelinated axons?
The tightly wound cell membranes of Schwann cells after the cytoplasm has
been squeezed out.
14. When, during an action potential, does sodium permeability incrase rapidly?
During the rising phase.
15. What type of proteins are ion channels?
They are integral membrane proteins.
16. What anesthetic was used in the endocrine experiment?
sodium pentobarbital, (Nembutal would be acceptable)
17. What is the "synapse" between the branch of a neuron and a
muscle cell called?
18. Depletion of what chemical after death causes rigor mortis?
19. How do you avoid retyping references each time you have a different
references are in a data base, styles are used to set specifics, EndNote
20. Comparative Medicine provided a digital scale. A container was on the
scale, and the scale was tared (set to read zero with the container on the
scale). What property of this scale made it especially well-suited to weighing
stayed stable despite movement
21. The Thanksgiving turkey has dark meat and white meat. Relate these to
twitch speed and means of ATP production. (2 points)
white, fast, anaerobic; dark, slow, aerobic
22. Where is the blind spot in the human?
about 15 degrees off-fovea, nasal retina (temporal visual field), on horizontal
23. You have copied a zoom of the Chart, and you have selected a new document
on Photoshop. A question about size pops up. How do you get it right?
Photoshop defaults to the size of what has been copied
24. What is the approximate duration of an action potential?
25. Explain the function of neostigimine, and describe why it is effective
in the treatment of myasthenia gravis. (2 points)
Acetylcholinesterase inhibitor, increases acetylcholine in decrease of acetylcholine
26. Using the force transducer in the computer and muscle labs, why did
you need to do a two point conversion under units of conversion?
because the y-axis defaulted to a voltage measurement, not grams
27. Why do you draw back on the syringe before injecting IP?
if you get fluid or blood, you are in an internal organ, not ip
28. In the "good" old days, when electrophysiologists used oscilloscopes,
how did they save their records?
29. What color is the choroid?
30. In addition to duration, voltage and frequency, the stimulator has a
knob for delay. Delay between what and what?
synch and stimulus (start of oscilloscope sweep and where the stimulus shows
31. The sodium-potassium pump pumps out __3__ sodium ions for every __2__
potassium ions that are pumped into the cell.
32. You are obtaining nice twitches with electrical stimulation of the forearm
using the force transducer. How would you get tetanus?
turn up the frequency
33. There are two types of actin. Give the names of both and describe (briefly)
the way they interact. (2 points)
globular polymerizes to filamentous
34. When acetylcholine binds its channel, which ions will move, and in which
direction will they move? (2 points)
Na+ in, K+ out
35. You have a tuning fork that is exactly 1000 Hz. An old audio oscillator
knob reads about 1000, and when both are presented to one ear simultaneously,
you hear 5 beats per second. (a) What is the cause of the beats? (b) Would
you be able to tell which has a higher pitch if they are presented to one
ear sequentially? (c) Would you hear beats if one is presented to one ear
and the other to the other? (3 points)
(a) physical interference, (b) definitely, (c) no, only at low frequencies
36. What are the gaps between regions of myelination called? Why are they
important? (2 points)
Nodes of Ranvier, speed up action potential propagation by saltatory conduction
37. An inflammation of a covering of the white of the eye is called pink
eye in lay jargon. What is that membrane?
38. Your teacher is trying to calculate the standard deviation of the quiz
scores using Excel. How is that done?
STDEV(first#on list:last#on list)
39. What does "20/20" mean?
You can see, at 20 feet, what a normal person can see at 20 feet
40. On which axis do you usually plot the independent variable?
41. Accomodation in the eye is accomplished by what structures?
ciliary muscle acting on lens
42. What would an outlier do to the standard deviation?
make it huge and make it less meaningful
43. What are the two parts of the electrochemical gradient?
electrical and chemical
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