Muscles contract in response to which of the following?

Question

Quizplus · Accepted Answer

Muscles produce movement by contracting in response to nervous stimulation.
Muscle cells contain protein filament. Each muscle cell consists of myofibrils, which in turn are made up of still smaller units called sarcomeres. These are both parts of the muscle cell, but not what causes a muscle to contract.
 Movement in muscles is produced due to contraction. Is it the response, not the cause.

Muscles Contract in Response to Which of the Following