Reflex actions are automatic and rapid so they can protect the body.They do not involve the conscious part of the brain:
The pain stimulus is detected by receptors.
Impulses from the receptor pass along a sensory neurone to the
3. An impulse then passes through a relay neurone.
4. A motor neurone carries an impulse to the effector.
5. The effector (usually a muscle) responds, e.g. to withdraw a limb
away from the source of pain.