Which type of neurons transmit impulses to the CNS from all parts of the body?

• A. Efferent neurons
• B. Afferent (sensory) neurons
• C. Interneurons
• D. Motor neurons

Answer: (B)

Afferent (sensory) neurons are responsible for transmitting impulses from sensory receptors throughout the body to the central nervous system (CNS). These neurons play a critical role in conveying information about the body's environment, both internal and external, allowing the CNS to process and respond to various stimuli.

This type of neuron is equipped with receptors that detect sensations such as pain, temperature, touch, and proprioception. Once stimulation occurs, these neurons generate electrical signals that travel along their axons to the spinal cord and the brain, where the information is interpreted and integrated.

In contrast, efferent neurons transmit signals away from the CNS to muscles and glands, facilitating responses (like movement). Interneurons, which act as connectors within the CNS, play a role in processing information but do not directly carry sensory information from the periphery. Motor neurons specifically convey impulses that control muscle contractions and glandular secretions but are distinct from the sensory pathways that afferent neurons operate within. This distinct function and pathway underline why afferent (sensory) neurons are the correct choice.