So at this point, they open up and this causes the depolarization of our membrane. So basically, as the sodium ions move down their electrochemical gradient and as they move into the cell, that causes the inside to go from negative to positive and the outside to go from positive to negative, as shown in this diagram. And that basically increases our cell voltage from negative 70 millivolts to about positive 45 millivolts. And this process is known as depolarization. Now, when we reach the positive 45 millivolt value, the sodium channels will close, they will become inactivated while the potassium channels will begin to open. And now no longer will the sodium move outside, but the potassium no longer will the sodium move inside, but the potassium will begin to move outside.