205textnotes08 - as K+ leaves cell, along its concentration...

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as K + leaves cell, along its concentration gradient, the inside becomes more negative; moving towards its Nernst potential. Nernst Potential: V = (RT/F) ln ([ion] out / [ion] in ) R = Universal gas constant (8.314 joules / °K · mol) T = temperature in °K F = Faraday's constant (96,000 coulombs / mol) [ion] = ion concentration (in or out of cell). Sodium's Contribution to the Resting Membrane Potential : - as Na + enters cell down concentration gradient, it makes the cell more positive inside; moving towards its Nernst potential. permeability of the cell membrane, at rest, is much higher (50-75 times) for K + than for Na + . This is a reflection of the larger number of open channels for K + compared to Na + . The resting potential of a neuron is therefore negative at approximately -70 mV. (NOTE: Most neurons are permeable to Cl - so that the ion distributes itself passively across the cell membrane.) The Na-K pump: The dissipation of ionic gradients is prevented by a Na-K pump. The pump moves 3 Na
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This note was uploaded on 12/26/2011 for the course KIN 205 taught by Professor Blaber during the Fall '09 term at Simon Fraser.

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