How do nerve impulses cause muscle contraction?
Skeletal muscle is under voluntary control. Nerve impulses that originate in the central nervous system cause muscles to contract. Both neurons and muscle tissue conduct electrical current by moving ions across cellular membranes. A motor neuron ends in a synapse with a muscle fiber. The neuron releases acetylcholine and transfers the action potential to the muscle tissue. The signal will travel through the tissue and trigger the contraction of individual sarcomeres. One synapse generally controls an entire muscle fiber. One motor neuron usually controls several adjacent muscle fibers. A group of fibers under the control of a single motor neuron is known as a motor unit. View the animation below, then complete the quiz to test your knowledge of the concept.
