Question

multiple choice question

which occurs during the contraction phase of a muscle twitch?

it is is depolarized.
it generates tension, pulling on its attachments.
it lengthens, releasing the pull on its attachments.

Explanation:

Define the phases of a muscle twitch

Using the Muscle Twitch and Myogram knowledge points, a single muscle twitch consists of three distinct phases: the latent period, the contraction phase, and the relaxation phase.

Analyze the contraction phase

During the contraction phase, cross-bridges form between actin and myosin filaments, leading to active sliding of the filaments. This molecular action generates active tension within the muscle fiber, causing it to shorten and pull on its connective tissue attachments.

Evaluate the given options

• "It is is depolarized.": Depolarization of the sarcolemma occurs during the action potential, which takes place during the latent period before physical tension begins.
• "It generates tension, pulling on its attachments.": This directly describes the contraction phase where cross-bridge cycling produces measurable force.
• "It lengthens, releasing the pull on its attachments.": This describes the relaxation phase, during which calcium is pumped back into the sarcoplasmic reticulum and tension declines.

Answer:

• It is is depolarized.
• It generates tension, pulling on its attachments. (Correct answer)
• It lengthens, releasing the pull on its attachments.