Structure of Skeletal Muscle

Structure of Skeletal Muscle - two types of filaments,...

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Structure of Skeletal Muscle A muscle fiber (cell) has special terminology and distinguishing characteristics:  •   The  sarcolemma,  or plasma membrane of the muscle cell, is highly invaginated by transverse  tubules (T tubes) that permeate the cell.  •   The sarcoplasm, or cytoplasm of the muscle cell, contains calcium-storing sarcoplasmic  reticulum, the specialized endoplasmic reticulum of a muscle cell. •   Striated muscle cells are multinucleated. The nuclei lie along the periphery of the cell, forming  swellings visible through the sarcolemma. •   Nearly the entire volume of the cell is filled with numerous long myofibrils. Myofibrils consist of 
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Unformatted text preview: two types of filaments, shown in Figure 1: Thin filaments consist of two strands of the globular protein actin arranged in a double helix. Along the length of the helix are troponin and tropomyosin molecules that cover special binding sites on the actin. Thick filaments consist of groups of the filamentous protein myosin. Each myosin filament forms a protruding head at one end. An array of myosin filaments possesses protruding heads at numerous positions at both ends....
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