When Muscle Is Stimulated Directly to Contract, Does the Rising

Multiple Choice

When muscle is stimulated directly to contract, does the rising phase of the twitch begin immediately? If not, why not?

A) No, the rising phase occurs only after a substantial number of muscle fibers have contracted.
B) No, electrical and chemical changes at the muscle membrane must occur before contraction.
C) No, the falling phase of the twitch must occur first.
D) Yes, it does begin immediately.