Reflex action: Reflex actions are automatic responses to stimuli. These actions are not under the control of the animal. They are of definite and mechanical type. Peripheral nervous system and spinal cord both control certain action and the brain is not in action.
Some examples of reflex actions are:
- Pupil becomes narrow when strong light falls on it.
- The aroma of the food makes the mouth watering.
- The hand is withdrawn as we touch the hot plate.
- Flow of bile from the gall bladder into the duodenum.
- A loud thud may lead to opening of the mouth.
In a reflex action brain is not involved, removing the hand on touching a hot plate is a reflex action. The impulse of heat goes from the hand to the spinal cord and the order is sent back to the muscles of the hand to remove the hand from the hot plate.