Which type of neuron carries impulses toward the CNS?

• A. Motor neurons
• B. Relay neurons
• C. Sensory neurons
• D. Interneurons

Answer: (C)

Direction of signal flow in the nervous system determines which neuron carries impulses toward the CNS. Sensory neurons, or afferent neurons, carry information from receptors in the body up to the brain and spinal cord, so the impulse travels toward the central nervous system. This handles sensations like touch, temperature, and pain. In contrast, motor neurons send impulses from the CNS to muscles or glands to cause a response, and interneurons (relay neurons) mainly operate inside the CNS to connect other neurons and process information. They don’t typically shuttle peripheral signals toward the CNS, which is why sensory neurons are the correct choice. For example, touching something hot sends a signal from skin receptors through a sensory neuron to the spinal cord, where it may be relayed to a motor neuron to pull the hand away.