Lab 2 - Lab 2 1. Basic anatomy: What is a skeletal muscle...

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Lab 2 1. Basic anatomy: What is a skeletal muscle fiber? Present a diagram that demonstrates the interaction between actin and myosin during contraction. What is the role of calcium, troponin and tropomyosin? Skeletal muscle fiber – single, multi-nucleated cylindrical shaped muscle cell. Many of these are bundled together by connective tissue to create a skeletal muscle fiber. Main structural feature is myofibrils, consisting of thick and thin filaments. Thick filaments are myosin and thin filaments are actin. A sarcomere is the basic contractile unit. Muscle Contraction AP arrives at bouton Ca2+ channels open and Ca2+ enters Ca2+ influx triggers release of Ach by exocytosis Ach diffuses across neuromuscular junction and binds to receptors on motor end plate Cation channels open Na+ enters and some K+ leaves This triggers end plate potential Current flow opens Na+ ion channels in membrane Na+ ion reduces threshold and initiates AP in muscle fiber and propagates to T-tubule AP in T-tubule releases Ca2+ from the SR Ca2+ binds to troponin on the actin filaments Movement of tropomyosin, which is connected to troponin, exposes actin molecules to form cross bridges with myosin Actin and myosin cross bridges bind and pulls thin filament inward, leading to a contraction (ATP is required)
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Lab 2 - Lab 2 1. Basic anatomy: What is a skeletal muscle...

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