What will you do if someone pricks yourhand with a needle? Elucidate the pathway of response with a neat labelled diagram.

Explanation

The pathway taken by nerve impulse to accomplish reflex action is called reflex arc.
(a) When the hand is pricked by a needle, the stimulus is the prick (touch) pain, which is sensed by receptor called as touch or pain receptors in the skin in our hand. This stimulus inturn triggers an impulse in sensory neuron.
(b) The sensory neuron transmits or conveys the message to the spinal cord.
(c ) The spinal cord interprets the stimulus and the impulse is passed on to the relay neuron, which inturn transmits it to a motor neuron.
(d) Motor neurons carry command from spinal cord to our arm.
(e) Muscle in our arm contracts and we withdraw our hand immediately from the needle prick. Muscle is the effector organ which has responded to the prick (pain).