Editing Threshold potential (section)

{{Short description|Critical potential value}}
[[Image:Action potential vert.png|thumb|350px|'''A.''' A schematic view of an idealized action potential illustrates its various phases as the action potential passes a point on a [[cell membrane]]. '''B.''' Actual recordings of action potentials are often distorted compared to the schematic view because of variations in [[electrophysiology|electrophysiological]] techniques used to make the recording.]]
In [[electrophysiology]], the '''threshold potential''' is the critical level to which a [[membrane potential]] must be [[depolarization|depolarized]] to initiate an [[action potential]]. In [[neuroscience]], threshold potentials are necessary to regulate and propagate signaling in both the [[central nervous system]] (CNS) and the [[peripheral nervous system]] (PNS).

Most often, the threshold potential is a membrane potential value between –50 and –55 [[volt|mV]],{{sfn|Seifter|Ratner|Sloane|2005|page=55}} but can vary based upon several factors. A [[neuron]]'s resting membrane potential (–70 mV) can be altered to either increase or decrease likelihood of reaching threshold via [[sodium]] and [[potassium]] ions. An influx of sodium into the cell through open, [[voltage-gated sodium channel]]s can depolarize the membrane past threshold and thus excite it while an efflux of potassium or influx of [[chloride]] can [[hyperpolarization (biology)|hyperpolarize]] the cell and thus inhibit threshold from being reached.