What other analogy can you use to describe the conduction of action potentials and activation of neurotransmitters?
I think of the action potential much as an electric roller coaster. Both require positive and negative polarity to propel an object. The roller coaster uses a combination of positive and negative charges to propel the cars, and the action potential is propelled by the positive and negative charges of sodium and potassium ions to propel the pulse down the Axon. Once the impulse is propelled to the next point on the Axon, the membrane goes into a resting state and is not capable of another impulse for a period of time, this makes it possible for the impulse to move forward, and prohibits it from moving backwards; slightly different that a roller coaster, but the effect remains the same.