Physiolab 9.0 Exercise 2

2165 Words Nov 8th, 2012 9 Pages
NAME Rachel Brockhuis
LAB TIME/DATE _______________________
Exercise 2
Skeletal Muscle Physiology

The Muscle Twitch and the Latent Period
1. Define the terms skeletal muscle fiber, motor unit, skeletal muscle twitch, electrical stimulus, and latent period. Motor unit- single α-motor neuron and all of the corresponding muscle fibers it innervates; all of these fibers will be of the same type
Skeletal muscle fiber- long and narrow cells that often span the entire length of a muscle
Skeletal muscle twitch- an activation of a muscle by firing a motor neuron
Electrical stimulus- the application of an electric current by means of a prosthesis to stimulate and restore partial function to a muscle disabled by neurologic lesions
Latent period-a
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Describe the force of contraction with each subsequent stimulus. Are these results called treppe or wave summation? When stimulating the isolated skeletal muscle multiple times in a short period with complete relaxation between each stimuli the amount of force between each stimulus increased progressively in step like form to a maximum peak in which a plateau of the force occurred. This is known as treppe.

3. How did the frequency of stimulation affect the amount of force generated by the isolated skeletal muscle when the frequency of stimulation was increased such that the muscle twitches did not fully relax between subsequent stimuli? Are these results called treppe or wave summation? How well did the results compare with your prediction? When the stimulation frequency was increased to the point in which muscle relaxation did not occur the amount of force progressively increased with each stimulus. When muscle twitches overlap, no muscles relax, and stimuli occurs one after another in a short amount of time, the muscle contraction is higher than if a single stand alone contraction had occurred

4. To achieve an active force of 5.2 g, did you have to increase the stimulus voltage above 8.5 volts? If not, how did you achieve an active force of 5.2 g? How well did the results compare with your prediction? No, I did not have to increase the stimulus voltage above 8.5 volts. In order to achieve an active force of 5.2g the stimuli needed to be…