BIOL 1003 Lecture Notes - Skeletal Muscle, Depolarization, Myofibril
14 Jan 2013
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Document Summary
Gross and microscopic structure of skeletal muscle including ultrastructure of a myofibril. Skeletal muscle is joined to bone by inelastic tendons: muscle contraction / pulls on tendons / bone moves. Each muscle is made of bundles of muscle fibres surrounded by connective tissue. Roles of actin, myosin, calcium ions and atp in myofibril. Striations in skeletal muscle are caused by filaments of two protein actin. Actin filament / thinner than myosin lighter striations. Myosin filament / thicker than actin filament darker striation. Distance between 2 adjacent z lines: sarcomere / actin filament is attached to z lines and extended into sarcomeres on either side. Striation of actin alone i band. Striation of myosin alone h zone. Central thickening of each myosin filament m line. Actin filament: 2 actin strands twisted around each other: troponin-tropomyosin-actin complex blocks binding site for myosin.
