Phys Ex

Topics: Skeletal muscle, Acetylcholine, Muscle Pages: 2 (330 words) Published: October 31, 2012
Exercise 2: Skeletal Muscle Physiology: Activity 1: The Muscle Twitch and the Latent Period Lab Report Pre-lab Quiz Results
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page 1

Experiment Results
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Experiment Data:


page 2

Post-lab Quiz Results
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page 3

Review Sheet Results
1. Define the terms skeletal muscle fiber, motor unit, skeletal muscle twitch, electrical stimulus, and latent period. Your answer:
Skeletal Muscle Fiber: composed of myofibrils, elongated, multinucleated Motor unit: a single motor neuron and muscle fibers that neuron activates Skeletal muscle twitch: contraction of small muscle units by impulses in the neurons supplying it electrical stimulus: an electrical current used to cause a single muscle or a group of muscles to contract latent period: delay between recieving a stimulus and the response 2. What is the role of acetylcholine in a skeletal muscle contraction? Your answer:

Ach is the chemical signal used to send to the muslce to cause contraction. 3. Describe the process of excitation-contraction coupling in skeletal muscle fibers. Your answer:
Ach is released at the neuromuscular jxn, Ach attaches to the receptors on the postsynaptic membrane, which opens the ion channels that allows for depolarization that leads to an AP that contracts muscles. 4. Describe the three phases of a skeletal muscle twitch.

Your answer:
Latent: delay between the stimulus and muscle contraction
Contraction: Muscle fibers shorten
Relaxation: muscles lengthen to their relaxed position
5. Does the duration of the latent period change with different stimulus voltages? How well did the results compare with your prediction?
Your answer:
No, the latenet period does not change with different stimulus voltages. 6. At the threshold stimulus, do sodium ions start to move into or out of the cell to bring about the membrane...
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