18. Long answer question III

 

The reflex arc describes the path taken by the nerve impulse electrical impulse as it travels from the neuron to the affectoreffector organ, which generates and shows the response.

 

The stimulus is prick (touch) pain, which is perceived by photo and chemoreceptorstouch or pain receptors  in the skin of our hand when the hand is pierced by a needle. This input in the tum causes a motor neuron sensory neuron  to release an impulse. The message is transmitted or conveyed to the spinal cord brain by the sensory neuronmotor neuron. The stimulation is interpreted by the spinal cord, and the impulse is sent to the sensory neuronrelay neuron, which in turn sends the signal to the relay neuronmotor neuron. The spinal cord skin send signal to our arm via motor neurons. Our arm muscle contracts, and we quickly pull our hand away from the needle prick. The effectoraffector organ that has responded to the puncture is muscle.