how is an ation potential generated?

An action potential is generated within the axon of a neuron via a series of steps:1) the inside of the neuron at rest is negative (-70mV), called the resting potential2) Na ion channels open and inside of the neuron becomes less negative (-55mV)3) at -55mV lots more Na channels open causing depolarisation (+40mV)4) potassium ion channels open which lets K diffuse out of the neuron making the inside less negative, called repolarisation (-80mV)5) K channels stay open longer than necessary causing the inside of the neuro to become more negative- hyperpolarisation6) back to resting potential, Na/K pump catches up to resting level