Describe what happens once acetylcholine is released from the synaptic end bulb into the neuromuscular junction....

Describe what happens once acetylcholine is released from the synaptic end bulb into the neuromuscular junction. Your explanation should explain everything that occurs during the muscle contraction.

Expert Solution

STEPS THEREAFTER:

Acetylcholine in NM junction binds to Nm receptor on motor end plate.

Propagation of action potential in the motor axon.

Release of acetylcholine that generates action potential in the sarcolemma

Inward spread of depolarization along T-tubules into the muscle

Dihydropyridine or DHP receptor sensors the action potential on T-tubules and relays it to RyR or Ryanodine receptor present on Terminal Cisternae (Sarcoplasmic Reticulum)

Ryanodine receptors provide a channel for release of calcium from sarcoplasmic reticulum into sarcoplasm.

Calcium enters the sarcoplasm and binds to Troponin-C.

Conformational change in troponin-tropomyosin complex.

Tropomyosin moves aside revealing myosin binding site on actin.

Myosin head binds to actin.

Increase ATPase activity of myosin head.

Release of Pi and energy.

Powerstroke which pulls thin filament towards the centre of sarcomere.

Muscle contraction with shortening of muscle (sarcomere).

Release of ADP from myosin which now remains bound to actin.

A new ATP binds with myosin after it detaches from actin.

The cycle continues till the motor signal persists.

Sydney Mullin answered 1 year ago

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