Name: Nabila Hana Zahirah Amri
Exercise 2: Skeletal Muscle Physiology: Activity 2: The Effect of Stimulus Voltage on Skeletal Muscle Contraction Lab Report
Pre-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.
1. Skeletal muscle fibers are innervated (stimulated) by You correctly answered: c. motor neurons.
2. A single action potential propagating down a motor axon results in
You correctly answered: d. a single action potential and a single contractile event in the muscle fibers it innervates.
3. In resting skeletal muscle, calcium is stored in You correctly answered: c. the sarcoplasmic reticulum.
4. During the latent period for an isometric contraction
You correctly answered: c. the cellular events involved in excitation-contraction coupling occur.
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10/29/23 page 2 Experiment Results
Predict Question:
Predict Question: As the stimulus voltage is increased from 1.0 volt up to 10 volts, what will happen to the amount of active force generated with each stimulus?
Your answer : a. The active force will continually increase.
Stop & Think Questions:
What do you see in the active force display when the stimulus voltage is set to 0.0, and why does this observation make sense?
You correctly answered: a. 0.00 g; there was no activation of skeletal muscle fibers by this stimulus.
What is the lowest stimulus voltage that induces active force in the skeletal muscle?
You correctly answered: b. threshold voltage
6. Enter the threshold voltage for this experiment in the field below and then click Submit Data to record your answer in the lab report
You answered: 0.8 volts
12. Enter the maximal voltage for this experiment in the field below and then click Submit Data to record your answer in the lab report.
You answered: 8.5 volts Experiment Data:
Voltage Length Active Force Passive Force Total Force
0.0 75 0.0 0.0 0.0
0.2 75 0.0 0.0 0.0
0.8 75 0.02 0.0 0.02
1.0 75 0.15 0.0 0.15
1.5 75 0.43 0.0 0.43
2.0 75 0.66 0.0 0.66
2.5 75 0.87 0.0 0.87
3.0 75 1.04 0.0 1.04
3.5 75 1.19 0.0 1.19
4.0 75 1.32 0.0 1.32
4.5 75 1.42 0.0 1.42
5.0 75 1.51 0.0 1.51
5.5 75 1.59 0.0 1.59
6.0 75 1.65 0.0 1.65
6.5 75 1.70 0.0 1.70
7.0 75 1.74 0.0 1.74
7.5 75 1.78 0.0 1.78
8.0 75 1.81 0.0 1.81
8.5 75 1.82 0.0 1.82
9.0 75 1.82 0.0 1.82
9.5 75 1.82 0.0 1.82
10.0 75 1.82 0.0 1.82
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10/29/23 page 11 Post-lab Quiz Results
You scored 100% by answering 6 out of 6 questions correctly.
1. Motor unit recruitment refers to
You correctly answered: a. an increase in the number of active muscle fibers to increase the force developed in a muscle.
2. Active tension (or force) in a skeletal muscle fiber results from
You correctly answered: a. activation of cross bridge cycling via increased intracellular calcium levels.
3. The ________ is the minimal stimulus needed to cause a depolarization of the muscle plasma membrane (sarcolemma).
You correctly answered: d. threshold voltage
4. By definition, the ________ is the amount of stimulus required to successfully recruit all the muscle fibers into developing active force.
You correctly answered: c. maximal voltage
5. Why was a maximal voltage observed in this experiment?
You correctly answered: b. At the maximal voltage, all the muscle fibers contained in this muscle are depolarized and they all develop active force (that is, they were all successfully recruited).
6. A sufficiently strong electrical stimulus applied to an isolated, mounted skeletal muscle induces the development of muscle force, or muscle tension. Which of the following statements concerning this observation is true?
You correctly answered: c. The electrical stimulus mimics acetylcholine release at a neuromuscular junction
10/29/23 page 12 Review Sheet Results
1. 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? How well did the results compare with your prediction?
You did not answer this question.
2. How is this change in whole-muscle force achieved in vivo?
You did not answer this question.
3. What happened in the isolated skeletal muscle when the maximal voltage was applied?
You did not answer this question.
