How do neurons transmit signals?

• A. By releasing neurotransmitters
• B. By propagating action potentials
• C. Through muscle contractions
• D. By generating spontaneous action potentials

Answer: (B)

Neurons transmit signals primarily by propagating action potentials. An action potential is a rapid change in the electrical charge of the neuron's membrane, which occurs when a neuron is stimulated above a threshold level. This change in voltage allows the signal to travel along the axon toward the synaptic terminals, where the neuron can communicate with other neurons or tissues.

As the action potential travels down the axon, it triggers the opening of voltage-gated sodium channels, allowing sodium ions to flow into the neuron and further depolarizing the membrane. This depolarization then leads to the opening of adjacent sodium channels, propagating the action potential along the length of the axon. Ultimately, this process allows for efficient and rapid transmission of nerve impulses over long distances, enabling complex signaling in the nervous system.

While neurotransmitters do play a crucial role in neuronal communication by crossing synapses and conveying signals between neurons, the question specifically asks about how signals are transmitted, which centers on the propagation of action potentials within individual neurons. Generating spontaneous action potentials can occur in certain types of neurons but is not the primary process used for signal transmission in response to stimulation. Muscle contractions are not directly involved in neuronal signal transmission but are a response mediated by neurons, particularly in