whats the physiology of an Action Potential and how it leads

what\'s the physiology of an Action Potential and how it leads to a muscle contraction.

key words :Sodium, Stimulus, Neurotransmitter (Acetylcholine), Permeable Cell membrane, calcium

Solution

A nerve stimulus triggers muscle contraction. When the neuronal signal reaches neuro-muscular junction, chemical Acetylcholine is released, which opens the chemical gated channels on the sarcolemma surface. Sodium ions present in the extracellular surface of sarcolemma travel through the voltage gated sodium ion channels into the intracellular space. This de-polarizes the membrane. Build up of sodium derived positive charge inside, makes potassium ions flow out via the voltage gated potassium-ion channels. Potassium ions outside the membrane help repolarize the membrane. Sodium and potassium ions come to their original levels via sodium-potassium ATPase pump.