What characterizes the reflex arc?

The reflex arc is characterized by the interaction between sensory and motor neurons, making the correct answer focus on this relationship. The reflex arc is a neural pathway that mediates a reflex action, and it typically consists of at least one sensory neuron transmitting a signal from a sensory receptor to the spinal cord, where it connects directly to a motor neuron. This motor neuron then sends a signal to an effector, such as a muscle, to elicit a response, such as pulling away from a hot surface.

While the reflex arc primarily operates at the spinal level and does not necessarily involve higher brain functions for immediate responses, this does not mean the brain is irrelevant in all reflexes; the brain can be involved in processing reflexive actions later. The involvement of sensory and motor neurons is crucial because it allows for the quick and efficient response to stimuli without the delay required for brain processing, emphasizing the interconnectedness of these components in forming a functional reflex arc.