How do the sodium and potassium ions maintain the resting potential of the neuron?

The plasma membrane of the neuron when at rest maintains an electric potential difference among its external and internal surfaces. This voltage is known as resting potential. The resting potential about -70 mV indicates that the interior is more negative than the exterior (negative polarization). This condition is maintained by transport of potassium and sodium ions across the plasma membrane.

The membrane is permeable to potassium ions but not to sodium ions. At rest the positive potassium ions exit the cell in favor of the concentration gradient as within the cell the potassium concentration is higher than in the extracellular space. The positive sodium ions cannot however go into the cell. As positive potassium ions exit the cell with not sufficient compensation of positive ions entering the cell, the intracellular space becomes more negative and the cell stays polarized.