muscle contraction definition | Psychology Dictionary

muscle contraction

a shortening of the muscle fibers in response to electrical stimulation from a motor neuron by which a muscle exerts force on the tissues to which it is attached. This stimulation initiates an electrochemical sequence in which myosin filaments, powered by ATP (adenosine triphosphate), detach from a nearby actin filament, swing forward to reattach further along the actin filament, and then swing back causing the actin and myosin filaments to slide in opposite directions. When this process is repeated in many muscle fibers, the overall muscle becomes shorter but thicker. See isometric contraction; isotonic contraction.

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muscle contraction

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