Threshold potential 598586 218458556 2008-06-10T19:12:11Z Bradv 6262758 Reverted to revision 166016627 by [[Special:Contributions/Richard001|Richard001]]; Restoring older version. ([[WP:TW|TW]]) [[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.]] The [[threshold potential]] is the [[membrane potential]] to which a membrane must be [[depolarization|depolarized]] to initiate an [[action potential]]. It often can be between −40 and -55 [[volt|mV]], but it can vary based upon several factors. If [[ion channel]]s are available, that will move the potential in the direction of the equilibrium potential for that ion: * [[sodium ion channel]]: Na+ is approximately +60mV * [[potassium channel]]: K+ is approximately -95mV * [[chloride channel]]: Cl- is approximately -70mV Therefore, [[resting ion channel]] for sodium will [[depolarization|depolarize]] and thus excite, while channels for potassium or chloride will [[hyperpolarization (biology)|hyperpolarize]] and thus inhibit. ==External links== * {{eMedicineDictionary|threshold+stimulus}} * {{GeorgiaPhysiology|1/1ch4/s1ch4_8}} * [http://www.cameron.edu/~gabrielr/PHYCH4/sld013.htm Description at cameron.edu] * [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mcb.figgrp.6213 Diagram at nih.gov] {{neuro-stub}} [[Category:Electrophysiology]] [[de:Schwellenpotential]] [[pl:Potencjał progowy]]