ANATOMY

Detailed explanation-1: -The main component is the actin filament, which is formed from the polymerization of globular actin molecules. Each globular actin monomer contains a binding site for the globular myosin head. Along the entire length of the thin filament, actin monomers spiral around a structural protein called nebulin.

Detailed explanation-2: -The thin filaments contain actin, tropomyosin, troponins C, I, and T and nebulin. The thick filaments are composed of myosin with the globular heads forming cross-bridges with thin filaments. Myosin-binding proteins, including MyBP-C, are associated with the thick filaments.

Detailed explanation-3: -Actin. The thin filament consists of two intertwined bands of actin monomers. Both skeletal and cardiac forms of actin are present during human cardiac development. In the early embryonic heart the skeletal form predominates (more than 80%).

Detailed explanation-4: -Most of the cytoplasm consists of myofibrils, which are cylindrical bundles of two types of filaments: thick filaments of myosin (about 15 nm in diameter) and thin filaments of actin (about 7 nm in diameter).

Detailed explanation-5: -There are about 300-400 globular actin molecules attached from end to end to form the helical strands of the thin filament, now called F actin (being fibrous). Each actin molecule has a binding site for a myosin cross bridge or head during the process of contraction.