What are the four steps in the contraction and relaxation of a skeletal muscle?
The four key steps are:
A skeletal muscle must be activated by a nerve, which releases a neurotransmitting chemical.
Nerve activation increases the concentration of calcium in the vicinity of actin and myosin, the contractile proteins.
The presence of calcium permits muscle contraction.
When a muscle cell is no longer stimulated by a nerve, contraction ends.