MUSCLE PHYSIOLOGY

Detailed explanation-1: -During muscle contraction, chemical energy is converted to mechanical energy when ATP is hydrolysed during cross-bridge cycling. This mechanical energy is then distributed and stored in the tissue as the muscle deforms or is used to perform external work.

Detailed explanation-2: -ATP prepares myosin for binding with actin by moving it to a higher-energy state and a “cocked” position. Once the myosin forms a cross-bridge with actin, the Pi disassociates and the myosin undergoes the power stroke, reaching a lower energy state when the sarcomere shortens.

Detailed explanation-3: -The contraction of myosin’s S1 region is called the power stroke (Figure 3). The power stroke requires the hydrolysis of ATP, which breaks a high-energy phosphate bond to release energy. Actin (red) interacts with myosin, shown in globular form (pink) and a filament form (black line). The model shown is that of H. E.

Detailed explanation-4: -The myosin head moves toward the M line, pulling the actin along with it. As the actin is pulled, the filaments move approximately 10 nm toward the M line. This movement is called the power stroke, as it is the step at which force is produced.