Question

multiple choice question

which occurs during the relaxation phase of a myogram?

• internal tension increases.
• muscle tension declines.
• external tension increases.

Explanation:

Define the phases of a muscle twitch

Using the Myogram and Muscle Twitch knowledge points, a muscle twitch consists of three distinct phases:

1. Latent period: The delay between the stimulus and the onset of contraction.
2. Contraction phase: Muscle tension rises to a peak as cross-bridges form.
3. Relaxation phase: Calcium ions are pumped back into the sarcoplasmic reticulum, cross-bridges detach, and muscle tension declines back to baseline.

Analyze the relaxation phase

Using the Skeletal Muscle Relaxation knowledge point, during the relaxation phase, active transport pumps actively return calcium to the sarcoplasmic reticulum. This decrease in sarcoplasmic calcium concentration prevents myosin from binding to actin. Consequently, the muscle fibers release their tension, causing the overall muscle tension to decline.

Evaluate the given options

• Internal tension increases: Incorrect, as tension is decreasing during relaxation.
• Muscle tension declines: Correct, as the muscle relaxes and returns to its resting length.
• External tension increases: Incorrect, as external tension decreases along with internal tension.

Answer:

• Internal tension increases.
• Muscle tension declines. (Correct answer)
• External tension increases.