(1) IONIC BASIS OF RESTING MEMBRANE POTENTIAL

• Na+ is actively transported out of the cell and K+ is actively transported in
• K+ diffuses back out of the cell due to its concentration gradient, while Na+ diffuses back into the cell
• At rest, the membrane is more permeable to K+ than Na+, leading to a greater passive efflux of K+ compared to the influx of Na+
• The membrane is impermeable to most anions in the cell, so the efflux of K+ is not balanced by an equal influx of anions
• This imbalance maintains the membrane in a polarized state, with the interior of the cell negatively charged and the exterior positively charged