Contraction

Contraction occurs by the mechanism of the sliding filament theory. This refers to the overlapping of actin and myosin protein filaments. Myosin heads bind to the myosin binding sites on the actin filament and push the actin filaments towards the centre of the sarcomere, this is the power stroke and results in muscle contraction. the myosine head will detatch from the actin binding site when ATP is present. The hydrolysis of ATP rotates the myosine head so that it is able to bind back to the actin filament. Rigamortis occurs due to no ATP being synthesised. thus the myosine head doesnt detatch from the actin filament and the muscles remain contracted.