Question

‘You open the test and page to the short answers.’ Doing so demands fine motor control. Select the correct statement about muscle action:

A. Both the contracting and the relaxing of the sarcomere in a muscle cell requires energy.

B. An action potential in a muscle cell, triggers the release of sodium from the sarcoplasmic reticulum in the muscle cell, which induces contraction of the sarcomere.

C. The contraction of a muscle depends on the physical interaction of protein filaments.

D. When the myosin molecules of the thick filaments shorten, the muscle contracts.