MUSCLE PHYSIOLOGY

Detailed explanation-1: -The bipolar thick filament is formed of approximately 300 myosin molecules and their associated proteins (Craig & Offer, 1976; Luther, Munro, & Squire, 1981). It has a strictly uniform dimension of 1.6 µm in length and 15 nm in diameter, which is independent of the type of muscle fiber (Huxley, 1963).

Detailed explanation-2: -The thick filament, myosin, has a double-headed structure, with the heads positioned at opposite ends of the molecule. During muscle contraction, the heads of the myosin filaments attach to oppositely oriented thin filaments, actin, and pull them past one another.

Detailed explanation-3: -In vertebrate striated muscles, the assembly of myosin molecules is arranged in such a way as to form bipolar filaments, with a central bare zone or M-region, where there are no myosin heads, corresponding to the centre of the sarcomere (Figure 5a).