A reflex arc is a neural pathway that mediates a reflex action, which is an automatic response to a stimulus that is not under conscious control. The sensory nerve of a reflex arc carries information from the receptor cell to the Central Nervous System (CNS), which is made up of the brain and the spinal cord. The sensory nerve fibers terminate in the spinal cord, where the synapse with interneurons transmit the information to motor neurons that control the effector organ.