Generation of Nerve impulses

Resting Membrane Potential (-70mV): Polarized state maintained by $Na^+/K^+$ pump (3 $Na^+$ out for 2 $K^+$ in). Axoplasm has high $K^+$, extracellular has high $Na^+$; Action Potential/Depolarization (+30mV): Stimulus opens $Na^+$ channels, massive influx of $Na^+$ reverses polarity; Repolarization: $Na^+$ channels close, $K^+$ channels open, $K^+$ efflux restores negative resting charge.