But now we wanna talk about how resting membrane potential is established.
So, one thing we know is that we need to establish the electrochemical gradient,
and that the sodium potassium ATPase is going to do that.
And when it does that, it's going to move three sodiums outside of the cell and
bring in two potassiums inside the cell.
So that's going to establish our gradient, but you'll notice that is sending out
three positive charges and only bringing back in two positive charges.
So the sodium potassium ATPase is going to establish a little bit
of a charge difference, which is going to cause a little bit of a negative membrane
potential because of that difference in numbers of positive ions that it's moving.
The other issue is what channels are open at rest.
So we said if only sodium channels are open, then the membrane potential is gonna
become the equilibrium potential for sodium.
If we open only potassium channels, then the membrane potential is
going to become the equilibrium potential for potassium.
If we open them up, sodium and potassium channels, so
that their membrane is permeable equally to those two ions,
then the membrane potential will reside in between the two equilibrium potentials.
So it will be proportional to whichever ion is most permeable.
And if the membrane is equally permeable to sodium and potassium,
then the membrane potential will reside between their equilibrium potentials.