How does an action potential propagate?

a stimulus depolarises the membrane potential above the threshold level e.g. -40 mvthis causes voltage gated Na+ ion channels to open- resulting in an influx of Na+ into the cellthis depolarises the membrane to +40 mvthen voltage gated K+ ion channels open resulting in an efflux of K+ out of the cell- this hyper polarises the cellthe Na-K pump restores the membrane potential