Textbook Question
Smooth muscle has some unique properties, such as low energy usage, and the ability to maintain contraction over long periods. Tie these properties to the function of smooth muscle in the body.
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9. Muscle Tissue
Steps of Muscle Contraction
Multiple Choice
When does the sarcoplasmic reticulum release calcium during muscle contraction?
A
During the hyperpolarization of the muscle fiber membrane
B
During the depolarization of the muscle fiber membrane
C
During the repolarization of the muscle fiber membrane
D
When the muscle fiber is at rest
Verified step by step guidance1
Understand the role of the sarcoplasmic reticulum (SR) in muscle contraction: The SR stores calcium ions (Ca²⁺) and releases them to initiate muscle contraction.
Recognize the phases of the muscle fiber membrane potential: depolarization, repolarization, and hyperpolarization.
Identify that during depolarization, the muscle fiber membrane potential becomes less negative, which is a signal for the SR to release calcium ions.
Know that the release of calcium ions from the SR into the cytoplasm of the muscle cell is crucial for the interaction between actin and myosin, leading to muscle contraction.
Conclude that the release of calcium from the SR occurs during the depolarization phase of the muscle fiber membrane, not during hyperpolarization, repolarization, or when the muscle is at rest.
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