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N5315 Advanced Pathophysiology Action Potentials I.Nerve Impulse a.Let us begin by reviewing some basic terms so that my explanation action potentials will make a little more sense. i.An action potential- is the membrane potential of an active neuron. One that is conducting an impulse. The process of conducting an impulse (action potential) involves a stimulus that activates the neuron → the neuron depolarizes → then repolarizes. ii.The refractory periodis a period of time during which the axon’s membrane resists stimulation and it cannot depolarize. 1.The absolute refractory periodoccurs when the membrane will not respond to ANYstimulus no matter how strong. 2.The relative refractory periodoccurs when the membrane is repolarizing and will only respond to a very strong stimulus. iii.Threshold Potential- is the point at which depolarization must reach in order to initiate an action potential. Otherwise the action potential will not occur.