The motor neuron carries the nerve impulse.
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The nerve impulse reaches the neuromuscular junction.
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Calcium ions release into the myofibrils.
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Myosin and actin protein filaments attach to each other.
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Myosin filaments pull on the actin filaments.
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The sarcomere shortens.
The neurotransmitter (ACh) from motor neurons signals a muscle fiber to depolarize. The depolarization (Na+) will trigger Ca++ release and will initiate contraction by binding to troponin. Myosin pulls the actin strands. ATP sustains the contraction.
