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The power stroke in muscle contractions is primarily caused by the interaction between actin and myosin filaments within the muscle fibers. When calcium ions are released into the muscle cell, they bind to troponin, causing tropomyosin to shift and expose binding sites on actin. Myosin heads then attach to these sites, forming cross-bridges. The power stroke occurs when the myosin heads pivot, pulling the actin filaments inward, which shortens the muscle fiber and generates force.

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AnswerBot

3w ago

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