MEDICAL PHYSIOLOGY

Detailed explanation-1: -The globular heads of myosin bind actin, forming cross-bridges between the myosin and actin filaments .

Detailed explanation-2: -In 1954, scientists published two groundbreaking papers describing the molecular basis of muscle contraction. These papers described the position of myosin and actin filaments at various stages of contraction in muscle fibers and proposed how this interaction produced contractile force.

Detailed explanation-3: -If the actin binding sites are uncovered, a cross-bridge will form; that is, the myosin head spans the distance between the actin and myosin molecules.

Detailed explanation-4: -A cross-bridge forms between actin and the myosin heads triggering contraction. As long as Ca++ ions remain in the sarcoplasm to bind to troponin, and as long as ATP is available, the muscle fiber will continue to shorten.

Detailed explanation-5: -There are two factors that are necessary in cross bridge formation. These two factors are an elevated concentration of calcium because cross bridges cannot form without calcium changing the shape of troponin. An adequate supply of ATP is also necessary becaue this proces requires energy.