Muscular System

Muscle Function

What are the four steps in the contraction and relaxation of a skeletal muscle?

The four key steps are:

  1. A skeletal muscle must be activated by a nerve, which releases a neurotransmitting chemical.

  2. Nerve activation increases the concentration of calcium in the vicinity of actin and myosin, the contractile proteins.

  3. The presence of calcium permits muscle contraction.

  4. When a muscle cell is no longer stimulated by a nerve, contraction ends.


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