Answer:
The general mechanism of muscle contraction involves the sliding filament theory. This theory states that muscle contraction occurs when the thin actin filaments slide over the thick myosin filaments, causing the sarcomere to shorten. The contraction is initiated when an action potential travels along a motor neuron to the neuromuscular junction, where it triggers the release of acetylcholine. This neurotransmitter then binds to receptors on the muscle cell membrane, which causes the release of calcium ions from the sarcoplasmic reticulum. The calcium ions then bind to troponin, which moves tropomyosin aside, exposing the binding site on the actin filament. The myosin head then binds to the actin filament, forming a cross-bridge. ATP is used to power the sliding of the myosin filament over the actin filament, causing muscle contraction. Finally, when the action potential ceases, the calcium ions are pumped back into the sarcoplasmic reticulum, allowing the muscle to relax.
Step-by-step explanation:
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