Action potential travels as what kind of signal along the axon?

• A. Electrical signal
• B. Chemical signal
• C. Magnetic signal
• D. Gravitational signal

Answer: (A)

An action potential travels along the axon as an electrical signal—a rapid, self-propagating change in membrane potential driven by voltage-gated ion channels. During this process, positively charged ions flow into and out of the neuron membrane, creating a wave of depolarization that moves from one segment of the axon to the next. This propagation is electrical because it’s the membrane potential itself that changes and spreads along the membrane, not a chemical substance moving along the axon. The signal can travel quickly and without decreasing in strength, especially in myelinated fibers where the impulse hops between nodes of Ranvier in a process called saltatory conduction. Outside the axon, communication between neurons at synapses occurs via chemical signals (neurotransmitters) or, less commonly, electrical gaps, but the conduction along the axon itself is fundamentally electrical. The other options describe signals that do not account for how the action potential moves along the axon.