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The threshold potential is the membrane potential to which a membrane must be depolarized to initiate an action potential.
It often can be between −40 and -55 mV, but it can vary based upon several factors. If ion channels are available, that will move the potential in the direction of the equilibrium potential for that ion:
- sodium ion channel: Na+ is approximately +55mV
- potassium channel: K+ is approximately -75mV
- chloride channel: Cl- is approximately -67mV
Therefore, resting ion channel for sodium will depolarize and thus excite, while channels for potassium or chloride will hyperpolarize and thus inhibit.
External links
- threshold+stimulus at eMedicine Dictionary
- Physiology at MCG 1/1ch4/s1ch4_8
- Description at cameron.edu
- Diagram at nih.gov
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- This page was last modified on 17 September 2008, at 22:43.
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