What is happening at 1 and 2 ? (b) Which nerve carried the impulse to the point marked 3?

Question

Observe the figure carefully and as per the numbers in that figure, answer the following questions.

(a) What is happening at 1 and 2 ?

(b) Which nerve carried the impulse to the point marked 3? In which direction is it conducting the impulse?

(c) Which is the nerve shown by 4?

(d) Which is the organ marked as 5?

(e) At 6, which nerve is conducting the response impulse?

(f) At 7, where has the impulse reached? What is its effect?

Answer 1

(a) At 1 stimulus of heat is received by thermoreceptors in the skin. At 2, the hand is withdrawn instantly.

(b) Sensory nerve carried the impulse to the point marked 3. The impulse is conducted from the skin towards the spinal cord.

(c) The nerve shown by 4 is association neuron. It is present in the gray matter of the spinal cord. It receives the sensory impulse, interprets it and generates impulse.

(d) Spinal cord.

(e) Motor nerve.

(f) At 7, the impulse has reached the muscles of the hand. As a result, the muscles contract and the hand is withdrawn instantly in response to the stimulus of heat.