Skeletal Muscle Contraction

What is the sequence of events that occurs at the neuromuscular junction (motor end plate)

1) a motor neuron fires an action potential down its axon

2) the motor neuron's axon terminal releases its ACh into the synaptic cleft

3) ACh binds to receptors on the junctional folds of the sarcolema

4) ACh binding sites causes a local depolarization called and end plate potential

What happens after the sequence of events at the neuromuscular junction

Muscle fiber excitation - The localized depolarization triggers an AP in the adjacent sarcolema

What happens after muscle fibers excitation

1) AP in sarcolema travels down the T-Tubules

2) sER release calcium ions

3) Calcium binds to troponin, which pulls tropomyosin, which uncovers the active site ion actin and allows for myosin heads to bind

How does contraction occur

Via cross bridge cycling; a result of the repeating cycle of steps that cause myofilaments to slide relative to each other