The structural unit of striated muscle, with several found in each fiber. They are, in fact, long, contractile cells with many nuclei, of which striated muscle is formed. the structural unit of striatedmuscle, a basic rod-like unit, several being found in each fiber, themyofibrils are made up of thick (composed mainly of the protein myosin) andthin (composed mainly of the protein actin) myofilaments, which give skeletalmuscle its striped appearance (see figure below). They are,in fact, long, fine contractile cells with many nuclei, of which striatedmuscle is formed, its fibers having long myofibrils running parallel long itslength. Actin and myosin form a complexprotein referred to as actomyosin. Thesemyofilaments repeat along the length of the myofibril in sections referred toas sarcomeres. Muscle contraction occursby sliding thin (actin) and thick (myosin) along each other during which theybind temporarily to each other before releasing. In effect, actin forms a ladder-likestructure when polymerized into filaments, which myosin filaments then ‘climb’to generate a contraction. Muscles contract is due to by the interaction actin and myosin by sliding the thin (actin) filaments and the thick (myosin) filaments along each other during which they briefly bind to each other.
