myosin and actin

An impulse is received by the neuromuscular junction

This is carried across the myofirbils via T tubules, Calcium ions are released from the endoplasmic reticulum.

The calcium ions bind to the troponin changing its shape so the troponin displaces the tropomyosin.

This has been blocking the actin filament. Now the myosin heads can bind the the actin filament. (forms a cross bridge)

ADP and Pi are released by the myosin head.

The myosin head then moves causing the actin filament to slide along the myosin filaments.

ATP is released which detaches the myosin head from the actin and then returns it to its original position, by moving ti forward. (energy)

The myosin head can then become reattached further down the filament.