1. A nerve impulse arrives at the neuromuscular junction.
2. The sarcoplasmic reticulum releases calcium ions, which diffuse through the sarcoplasm.
3. The calcium ions attaches to a troponin molecule which causes it to move.
4. This causes the tropomyosin to move on the actin and reveal the myosin head binding site on the actin.
5. The myosin head binds to this binding site, forming a cross bridge. This uses ATP which then releases ADP and a phosphate ion.
6. The myosin then changes shape which leads to the myosin head nodding foreward and it pulls the actin over itself.
7. ATP then attaches to the binding site which causes it to dettatch. Then the ATPase on the myosin head hydrolyses the ATP into ADP and a phosphate ion.
8. The hydrolysis causes the myosin head to change shape again and leaves it in an upright position.
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