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[Neuroscience] Re: membrane voltage equations which one

r norman via neur-sci%40net.bio.net (by r_s_norman from comcast.net)
Mon Sep 6 07:34:14 EST 2010


On Sun, 5 Sep 2010 20:13:26 -0700 (PDT), Bill
<connelly.bill from gmail.com> wrote:

>On Sep 6, 11:07 am, Bill <connelly.b... from gmail.com> wrote:
>
>> where I = Ó Gx (Ex-V)
>
>That "Ó" was supposed to be a SIGMA... sum of all Gx(Ex-V) across all
>ions

This is a better account of what is really happening in the cell.

My simplified equation represented the membrane as a simple RC
circuit, something useful in computing cable properties for example.

Bill's addition expands the ionic current into the separate sodium,
potassium, and other components reflecting the way that ohmic current
really crosses the membrane and also accounting for the fact that each
separate ionic current involves a reversal potential or Nernst
equilibrium.

It only lacks the inclusion of current derived from, for example, an
external stimulus, but that is easily added to the sum.



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