Describe the physiology that occurs at the neuromuscular junction starting from

Question

Describe the physiology that occurs at the neuromuscular junction starting from the time that an action potential (nerve signal) arrives at the synaptic end bulb to the time that an action potential is initiated and propagated down the sarcolemma. You should mention at least 4 things that happen at the neuromuscular junction that you think are important. (4) Do not include the neuronal action potential or anything beyond the muscle fiber action potential in this answer.

          Explain in physiological terms what would happen to muscle contraction if the acetylcholine receptor were somehow blocked and Ach was unable to bind to the receptor. Be specific in your answer. (3)

Explain in physiological terms what would happen to muscle contraction if voltage gated sodium channels along the sarcolemma were somehow inhibited, and sodium was unable to pass through them. Be specific in your answer (3) (10 points total)

Explanation / Answer

Actions at neuromuscular junction:

1.Release of acH:

when a nerve impulse reach the synaptic bulb it triggers the release of aCH from synaptic vesicles that contain aCH

2.Activation of aCH receptors:

Motor end plate receptors onto which the free aCH binds after diffusing across the synaptic cleft

The binding of aCH to aCH receptors causes ion channels to open so that sodium ions flow across the membrane to the muscle

3.Generation of muscle action potential:

The flow of sodium ions across the membrane to the muscle generates a action potential this travels along sarcolemma and T tubule

4.Breakdown of ACH:

It occurs within synaptic cleft.The breakdown occurs by acetylcholine esterase enzyme

2.If acetylcholine is blocked muscle contraction is prevented by blocking the post synaptic action potentials

3.If sodium channels are inhibited

Some agents like lignocaine binds to voltage gated sodium channels blocks the conduction of action potential

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