Asked by james P-Val on May 05, 2024
Verified
Which part of a muscle twitch occurs when the sarcomere distance is decreasing?
A) latent period
B) contraction period
C) relaxation period
D) refractory period
E) expansion period
Sarcomere Distance
The length between two Z lines in a muscle fiber, defining the fundamental unit of muscle contraction.
Muscle Twitch
Single contraction of a muscle fiber; typically lasts only a fraction of a second.
Contraction Period
The phase during muscle activity where the muscle fibers shorten, generating force.
- Explain the mechanisms behind muscular contraction and detail the biochemical reactions facilitating muscle contraction and relaxation.
Verified Answer
SG
Sonya GonsalezMay 11, 2024
Final Answer :
B
Explanation :
The contraction period is when the sarcomere distance is decreasing as the actin and myosin filaments slide past each other, causing the muscle fiber to shorten and generate force. The latent period is the brief delay between the stimulus and the start of the contraction, during which the action potential spreads along the sarcolemma and calcium ions are released from the sarcoplasmic reticulum. The relaxation period occurs when the sarcomere distance is increasing again as the muscle fiber returns to its resting length and tension decreases. The refractory period is the time during which the muscle fiber cannot be stimulated again, due to the closure of voltage-gated ion channels. There is no such thing as an expansion period in muscle twitch.
Learning Objectives
- Explain the mechanisms behind muscular contraction and detail the biochemical reactions facilitating muscle contraction and relaxation.