Question

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

Answer 1

Reflex action and its pathway

The pathway taken by nerve impulses to accomplish reflex action is called the reflex arc.

• When the hand is pricked by a needle, the stimulus is the prick (touch) pain, which is sensed by a receptor called touch or pain receptors in the skin in our hand. This stimulus in tum triggers an impulse in a sensory neuron.
• The sensory neuron transmits or conveys the message to the spinal cord.
• The spinal cord interprets the stimulus and the impulse is passed on to the relay neuron, which in tum transmits it to a motor neuron.
• Motor neurons carry commands from the spinal cord to our arms.
• The muscle in our arm contracts and we withdraw our hand immediately from the needle prick. The muscle is the effector organ that has responded to the prick (pain).