Define the reflex arc and state its components.
Reflex arc:
It is a shortest pathway for an impulse to travel from the receptor organ via central nervous system to the effector.
Components of the reflex arc:
Stimulus→ Receptor(through sensory neurons)→ brain or spinal cord→ (through motor neuron)effector → response.
Hence, reflex arc is the pathway of an impulse to the effector via the central nervous system which includes a receptor, a sensory neuron, a motor neuron, brain and spinal cord and an effector.