Which statement about the structure of skeletal muscle is true?
A) The light bands of the sarcomere are the regions where actin and myosin filaments overlap.
B) When a muscle contracts,the A bands of the sarcomere lengthen.
C) The actin filaments are anchored by titin molecules to the Z lines.
D) When a muscle contracts,the H zone of the sarcomere shortens.
E) The sarcoplasm of the muscle cell is contained within the sarcoplasmic reticulum.

Question

Quizplus · Accepted Answer

When a muscle contracts, the H zone of the sarcomere, which is the region where only myosin filaments are present, shortens. The A band, which contains both actin and myosin filaments, remains the same length. The light bands, also called the I bands, contain only actin filaments and shorten during muscle contraction as well. The actin filaments are anchored by the Z lines, not titin molecules, and the sarcoplasm is the cytoplasm of the muscle cell and is separate from the sarcoplasmic reticulum, which is an organelle involved in the storage and release of calcium ions for muscle contraction.

Which Statement About the Structure of Skeletal Muscle Is True