Biology 347 - General Physiology Lab - Stark and Kumar - Fall 2004
Midterm - 10/7/04 (each question is 1 point unless specified) 50 points total

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 being stimulated.

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 scale?

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 cells?

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 unit.

9. What are the interconnecting tubules of Ca2+-containing endoplasmic reticulum that surround each myofibril?

Sarcoplasmic reticulum

10. Which part of the contractile apparatus that contains both thin and thick filaments?

A band

11. When, during an action potential, is potassium permeability the greatest?

During repolarization.

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?

neuromuscular junction

18. Depletion of what chemical after death causes rigor mortis?


19. How do you avoid retyping references each time you have a different journal's style?

references are in a data base, styles are used to set specifics, EndNote was demonstrated

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 the mice?

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 plane

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?

1 ms

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 receptors

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 up)

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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