MUSCLE PHYSIOLOGY

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

Detailed explanation-2: -This process is known as myosin-actin cycling. As the myosin S1 segment binds and releases actin, it forms what are called cross bridges, which extend from the thick myosin filaments to the thin actin filaments. The contraction of myosin’s S1 region is called the power stroke (Figure 3).

Detailed explanation-3: -The muscle contraction cycle is triggered by calcium ions binding to the protein complex troponin, exposing the active-binding sites on the actin. As soon as the actin-binding sites are uncovered, the high-energy myosin head bridges the gap, forming a cross-bridge.

Detailed explanation-4: -Actin is a thin contractile protein found in the muscle cells, whereas myosin is a thick contractile protein found in muscle cells. The heads of actin and myosin form a cross-bridge, generating muscle contraction. Muscle contraction occurs when the thin actin and thick myosin filaments slide past each other.

Detailed explanation-5: -So, the correct answer is ‘Binding of ATP to the myosin head’.