The entire process of response to a peripheral nervous stimulation, that occurs involuntarily effort or thought requiring the involvment of a part of the central nervous system is called a reflex action.

The reflex pathway comprises of:

i. One afferent neuron (receptor) at least one.
ii. One efferent (effector or excitor) neuron appropriately arranged in a series

The afferent neuron receives signal from a sensory organ and transmits the impulse through the dorsal nerve root into the CNS at the level of spinal cord. The efferent nueuron carries signals from CNS to the effector. The stimulus and response thus forms a reflex arc .