In its resting state, a neuron is at -70mV, this is called resting membrane potential. When the nerve is stimulated an action potential is created. An action potential is generally triggered at 30mV. Once an action potential is triggered it can not be stopped. The action potential travels only in one direction, towards the next neron. The action potential creates an impulse that travels down the axon. If the axon is myelinated the impulse will travel faster. The axons ends in axon terminals which end in synapses. Once the impulse gets to the synapse it will trigger the release of neurotransmitters which starts a chain reaction that will pass the impulse to the next neuron.