muscle contraction

 The sliding filament theory describes how muscle contraction occurs 

• An action potential travels into the muscle fibre via T tubules, causing release of calcium ions from the sarcoplasmic reticulum. The calcium ions bind to the tropomyosin molecules and cause them to move, exposing the myosin binding site on the actin filament. Myosin attaches to actin forming a actin-myosin cross-bridge. ATPases hydrolyse ATP to detach…