Question

A person walks across a room in barefeet and puts his foot on a drawing pin lying on the floor. He lets out a cry. Explain what happens in his nervous system in bringing about this response.

Answer 1

It is an example of reflex action. The stimulus here is drawing pin lying on the floor. The pain is  sensed by the receptors in the skin which triggers and impulse in a sensory neuron and transmits the message to the spinal cord. The impulse is passed onto a relay neuron, which in turn, passes it to the motor neuron. The motor neuron passes the impulse to a muscle in the feet. The muscle then contracts and pulls our feet away from the drawing pin.