When a sarcomere contracts and thin filaments move over thick filaments you would expect to see ________.
A) the H zone to appear wider
B) the I bands to appear smaller
C) the I bands to appear wider
D) the A band to appear darker

Question

Quizplus · Accepted Answer

During sarcomere contraction, the distance between the Z lines decreases as thin filaments slide over thick filaments, causing the I bands to appear smaller. The H zone also appears smaller, while the A band remains the same width but appears darker due to the overlap of thin and thick filaments. The correct answer is B because the I bands are the only structures directly involved in the sliding filament model of muscle contraction that change in size.

When a Sarcomere Contracts and Thin Filaments Move Over Thick