How is an action potential generated?

An action potential is the propagation of the reversal of charge across a membrane voltage gated Na+ ion channels sense a change in membrane potential causing them to open Na+ moves down its concentration gradient and into the axon seeing it become more positive (depolarisation)this continues until action potential is reached (+40mV) where the Na+ ion channels close voltage gated K+ channels open K+ moves down concentration gradient and out of axon seeing the membrane become more negative (repolarisation)once resting potential (-70mV) is reached there is a delay in the closing of K+ channels (hyperpolarisation)the Na/K ATPase pump restores resting potential (at -70mV) by pumping 3Na+ in and 2K+ out