Summarise muscle contraction (7)

Motor neuron = releases Ca ions from SP reticulum Ca binds to trop causes tropomyo to move = exposes binding sites for myosin heads actin + myosin form crossbridge that is broken by ATP ATP hydrolysis causes myosin to swivel and change position moved heads binds to actin Returns to original position (Releases ADP + P) Moves the actin to the center of the sarcomere actin sliding = shortens sarcomere = muscle contraction