In a reflex action, sensory neurons and relay neurons meet at a synapse within the central nervous system, specifically in the spinal cord. When a sensory neuron detects a stimulus, it sends an electrical impulse to the spinal cord, where it forms a synapse with a relay neuron (also known as an interneuron). This relay neuron then processes the stimulus information and passes the signal to a motor neuron, which carries the impulse to an effector such as a muscle to produce a rapid response. This synapse between the sensory neuron and the relay neuron in the spinal cord allows quick and automatic reflex actions without involving the brain directly.
Thus, the meeting point of sensory and relay neurons in a reflex arc is the synapse inside the spinal cord gray matter, enabling the fast processing of stimuli and immediate motor response.
