MUSCLE PHYSIOLOGY

Detailed explanation-1: -Sliding-filament model of muscle contraction. The actin filaments slide past the myosin filaments toward the middle of the sarcomere .

Detailed explanation-2: -Actin filaments slide inward on myosin, drawing the Z-lines toward the center of the sarcomere and shortening the muscle fiber. As actin slides over myosin, the H-zone and I-band shrink. The flexion of myosin cross-bridges pulling on actin is responsible for the movement of the actin filament.

Detailed explanation-3: -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.

Detailed explanation-4: -The sliding filament theory describes the mechanism that allows muscles to contract. According to this theory, myosin (a motor protein) binds to actin. The myosin then alters its configuration, resulting in a “stroke” that pulls on the actin filament and causes it to slide across the myosin filament.

Detailed explanation-5: -Actin filaments (F-actin) are linear polymers of globular actin (G-actin) subunits and occur as microfilaments in the cytoskeleton and as thin filaments, which are part of the contractile apparatus, in muscle and nonmuscle cells (see contractile bundles).