MICROANATOMY

Detailed explanation-1: -The myofilament contractile proteins consist of thick filament myosin and thin filament actin proteins. Bound to actin are a complex of regulatory proteins, which include tropomyosin and troponin-T, C, and I.

Detailed explanation-2: -Myofilaments are the three protein filaments of myofibrils in muscle cells. The main proteins involved are myosin, actin, and titin. Myosin and actin are the contractile proteins and titin is an elastic protein.

Detailed explanation-3: -The I bands contain only thin (actin) filaments, whereas the A bands contain thick (myosin) filaments. The myosin and actin filaments overlap in peripheral regions of the A band, whereas a middle region (called the H zone) contains only myosin.

Detailed explanation-4: -The myofibrils are made up of thick and thin myofilaments, which give the muscle its striped appearance. The thick filaments are composed strands of the protein myosin, and the thin filaments are strands of the protein actin, along with two other muscle regulatory proteins, tropomyosin and troponin.

Detailed explanation-5: -Skeletal muscle is composed of a repeating structure of myosin and actin fibers. Each myosin thick filament is surrounded by actin thin filaments, and each thin filament is surrounded by thick filaments. Several of these filament bundles make up the functional portion of a muscle cell.