A resting membrane potential is the voltage difference between the cell body and the dendrites. An action potential is a graded potential. The voltage difference across the membrane reverses. Potassium gates close. Sodium gates open.
Potassium rushes into the neuron.
Early researchers studied neuron function by recording the effects of stimulation on the giant axon of a species of sea slug. A myelin sheath is a type of neuron. It causes degeneration of the myelin sheaths. It prevents the release of ACh by presynaptic cells. It prevents the removal of dopamine from the synaptic cleft.