ANATOMY

Detailed explanation-1: -The cross bridge cycle is the sequence of events in the thick and thin filaments of a muscle that result in its contraction. It starts with the myosin head binding and hydrolysing ATP into ADP and phosphate.

Detailed explanation-2: -The ATP is hydrolyzed into ADP and inorganic phosphate (Pi) by the enzyme ATPase. The energy released during ATP hydrolysis changes the angle of the myosin head into a “cocked” position, ready to bind to actin if the sites are available. ADP and Pi remain attached; myosin is in its high energy configuration.

Detailed explanation-3: -Following the release of the myosin head from actin, hydrolysis of the ATP to ADP + Pi causes the myosin head to become re-cocked from the 45-to the 90-degree position, and the cross-bridge cycle begins again.

Detailed explanation-4: -The motion of muscle shortening occurs as myosin heads bind to actin and pull the actin inwards. This action requires energy, which is provided by ATP. Myosin binds to actin at a binding site on the globular actin protein.

Detailed explanation-5: -Actin-myosin cross-bridge is formed when actin and myosin heads become linked together. In general, a myosin head flexes and delivers a power stroke when it binds to an actin filament. The force which is generated from the power stroke is due to the moving of the actin filament past the myosin.