The electrical signal in neurons is called what?

• A. Neural impulse
• B. Electrical current
• C. Impulse
• D. Action potential

Answer: (D)

The electrical signal in neurons is the action potential. It is a rapid, transient change in the neuron's membrane potential that travels along the axon. When the membrane depolarizes to a threshold, voltage-gated sodium channels open and Na+ rushes into the cell, making the inside more positive. This is followed by the opening of potassium channels and the efflux of K+, which brings the membrane potential back toward negative. This sequence is regenerated along the length of the axon, so the signal propagates without diminishing strength (an all-or-none event). Action potentials are the precise mechanism that converts electrical activity into the chemical signaling that occurs at synapses, triggering neurotransmitter release. Other terms like neural impulse, impulse, or electrical current are less specific or describe more general concepts, whereas action potential uniquely identifies the neuron’s signaling event.