1. The latent period of the skeletal muscle that was tested in this lab simulation was
a. about 1 second.
b. less than 1 msec.
c. between 2-3 msec.
d. variable, depending on the voltage that was applied to it.
2. True or False: Another name for a muscle cell is “myofibril.”
3. The largest active force that could be generated in the muscle is Activity 1 was _______ grams.
4. Define the terms skeletal muscle fiber, motor unit, skeletal muscle twitch, electrical stimulus, and latent period.
5. What is the role of acetylcholine (ACh) in a skeletal muscle contraction?
6. Describe the process of excitation-contraction coupling in skeletal muscle fibers.
7. Describe the three phases of a skeletal muscle twitch.
8. Does the duration of the latent period change with different stimulus voltages?
9. At the threshold stimulus, do sodium ions start to move into or out of the cell to bring about the membrane depolarization?
ACTIVITY 2: The Effect of Stimulus Voltage on Skeletal Muscle Contraction
10. The threshold voltage for the muscle in this lab simulation was ________ volts. When that voltage was used to stimulate the muscle, ________ grams of active force were generated.
11. True or False: In a resting skeletal muscle cell, most of the calcium ions freely move through the cytoplasm of the cell.
12. Describe the effect of increasing stimulus voltage on isolated skeletal muscle. Specifically, what happened to the muscle force generated with stronger electrical stimulations and why did this change occur?
13. How is this change in whole-muscle force achieved in vivo (eg. in the human body)?
14. What happened in the isolated skeletal muscle when the maximal voltage was applied?
ACTIVITY 3: The Effect of Stimulus Frequency on Skeletal Muscle Contraction
15. True or False: There is no limit to the amount of force that a skeletal muscle can generate if it is stimulated by a high enough voltage at a very high frequency.
16. The chemical ion or molecule that is primarily responsible for initiating the contraction of a muscle fiber is
a. Na+
b. K+
c. Ca2+
d. ADP
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