Resting Membrane Potential

1. At resting state, effectively the only open channels are |K+| channels; other ions have no available channels, therefore experience infinite resistance and no current.

2. |K+| is actively pumped into the cell, so that there is much more |K+| inside than outside the cell.

3. |K+| can follow its concentration gradient by diffusing from the cell through open channels to the extracellular fluid. As these + ions leave, the cell membrane becomes more negative.

4. |Na+| is actively pumped out of the cell, but cannot flow back in until |Na+| channels open. Likewise, |Cl-| cannot leave the cell.

5. |K+| will continue to leave the cell until the membrane is so negatively charged that the electrical force balances the driving force of the electrical gradient.