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SUMMARY
The immense power generated
by muscular contraction is the result of the coordinated
interaction of millions of microscopic molecules.
Upon nervous stimulation, an influx of Ca2+
ions frees myosin binding sites on actin filaments,
enabling the formation of actin-myosin cross bridges.
Once cross-bridge formation is enabled, the energy
stored in cytoplasmic ATP molecules powers the
repeated cocking, attachment, flexion, and release
of the myosin heads against the actin filaments.
As this process is repeated by hundreds of millions
of myosin heads simultaneously, the resulting
contraction of millions of sarcomeres results
in the large-scale muscle contractions necessary
to cause bodily movements.
Activity
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