And the way that that takes place is via these special proteins that passively pump these ions. Now, this means that if we move positive charge from the outside of the cell to the inside of the cell, this inside will become slightly more positive, that is, slightly less negative. So this value of negative 87 millivolts will become more positive because this membrane is slightly permeable to our sodium. And so some of these sodiums will be brought to the inside, and so this will become more positive. And that's exactly why the actual value for the voltage difference of the rustic membrane is around negative 70 millivolts. Because the membrane is not only permeable to our potassium, it's also slightly permeable to our sodium.