What is meant by resting membrane potential?

Explanation

Resting membrane Potential: The electrical potential difference across the plasma membrane of a resting neuron is called the resting potential during which the interoro of the cell is negative due to greater efflux of `K^+` outside the cell than `Na^+` influx into the cell. When the axon is not conducting any impulses i.e. in resting condition, the axon membrane is more permeable to `K^+` and less permeable to `Na^+` ions, whereas it remains impermeable to negatively charged protein ions.

The axoplasm contains high concentration of `K^+` and negatively charged proteins and low concentration of `Na^+` ions. In contrast, fluid outside the axon (ECF) contains low concentration of `K^+` and high concentration of `Na^+`, and this forms a concentration gradient. This ionic gradient across the resting membrane is maintained by ATP driven Sodium-Potassium pump, which echanges `3Na^+` outwards for `2K^+` into the cells. In this state, the cell membrane is said to be polarized. In neuron, the resting membrane potential ranges from –40mV to –90mV, and its normal value is –70mV. The minus sign indicates that the inside of the cell is negative with respect to the outside.