This is true as long as you aren't injecting current through a microelectrode. The sum Ii + Ic = Im, the total membrane current, and Im must equal the injected current Iinj. If Iinj is 0, Ii = -Ic.Bill Connelly wrote:A statement I read all the time is the "total membrane ionic current must be equal and opposite to the total membrane capacitive current"
First, step back from the problem and recall that the voltage across a capacitor is proportional to the charge stored in the capacitor. The charge stored in a capacitor is the integral of Ic. So if current flows through membrane capacitance, membrane potential changes.if at any point of time I-membrane = -I-cap then wouldn't there be no change in membrane voltage?
Bill Connelly wrote:I-ion + I-cap = 0
I-mem = I-ion + I-cap
I-m = 0
No transmembrane current, no change in membrane voltage.
True.Bill Connelly wrote:it is the current that flows across the capacitor that changes the membrane potential
True.then Ii doesn't change the membrane potential? It just supplies current to charge?
No. Here's how to think about it.isn't the direction of current flows across the capacitor in the wrong direction?
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