How can an action potential be described?

An action potential is characterized by a large, rapid change in the electrical charge across a neuron’s membrane, transitioning from a negative internal charge to a positive one. This occurs when a neuron is stimulated beyond a certain threshold, causing voltage-gated sodium channels to open. Sodium ions flood into the cell, shifting the membrane potential from a resting state (typically around -70mV) to a peak positive value (around +30mV).

This drastic change is crucial for the transmission of electrical signals along neurons, allowing them to communicate with one another, as well as with muscle cells and glands. The action potential is an all-or-nothing response; once the threshold is reached, the potential will always change in a similar and predictable manner, regardless of the strength of the stimulus as long as that threshold is surpassed.

In contrast, the other options do not adequately describe this phenomenon. A small change in electrical charge may refer to local potentials rather than action potentials. Stability in electrical charge implies a lack of significant change, which is not the case with action potentials. A fluctuation in cellular potential could imply varying changes that do not necessarily characterize the specific and distinct process of an action potential.