Final answer:
Action potentials cannot stop abruptly or reverse direction because they are an all-or-none event that progresses to completion once initiated. A refractory period follows an action potential, preventing the immediate initiation of another one. Potassium and sodium ion pumps aid in resetting the resting potential.
Step-by-step explanation:
No, the action potential cannot stop abruptly nor reverse direction once it has started. An action potential is an all-or-none event; this means that once the threshold of excitation is reached and the action potential begins, it travels all the way down the axon until it reaches the terminal buttons.
During an action potential, a cell undergoes depolarization due to the influx of Na+ ions, followed by repolarization as K+ ions flow out of the cell. This process is tightly controlled by voltage-gated ion channels. While an action potential is underway, a refractory period sets in, which includes two phases: the absolute refractory period, where no new action potential can be initiated due to the inactivation of Na+ channels, and the relative refractory period, which requires a stronger stimulus to initiate another action potential due to the continuing efflux of K+ ions.
The role of potassium and sodium ion pumps is also crucial as they help to reset the resting potential after an action potential has occurred, which enables the neuron to become ready for another signal transmission.