Contraction of muscle can be caused by
Release of noradrenaline
Release of acetylcholine
Release of serotonin
Release of histamine
The process by which the contraction of muscle is brought about is a sliding of the thin filaments over the thick filaments. STEPS INCLUDE: Discharge of motor neuron.Release of transmitter (acetylcholine) at motor end-plateIncreased Na+ and K+ conductance in end-plate membraneGeneration of end-plate potential.Inward spread of depolarization along T tubulesRelease of Ca2+ from terminal cisterns of sarcoplasmic reticulum and diffusion to thick and thin filaments Formation of cross-linkages between actin and myosin and sliding of thin on thick filaments, producing movement.(REF.GANONG'S REVIEW OF MEDICAL PHYSIOLOGY -23rd EDITION. Page No-100)
General physiology