Reflex action is a fast, involuntary unplanned sequence of actions that occurs in response to a particular stimulus, e.g., closing the eyelids when dust falls in the eyes, withdrawing hand on touching a hot pan. It is brought about by the spinal cord. The nervous elements involved in carrying out the reflex actions constitute a reflex arc.
Reflex arc-has:-
1. Sensory receptors: It is a sensory structure that responds to a specific stimulus.
2. Sensory neuron: This neuron takes sensory impulse to the grey matter of the spinal cord through the dorsal root of the spinal cord.
3. Interneurons: one or two intemeurons serve to transmit impulses from the sensory neuron to the motor neuron.
4. Motor neuron: It transmits impulse from the central nervous system to the effector organ.
5. Effector organs: It may be a muscle or gland which responds to the impulse received.
