Explain the terms “vasodilation” and “vasoconstriction”. How do these processes contribute in the regulation of the body temperature?

How does our skin provide protection to our body against the following?

a) Entry of germs

b) Excessive loss of heat in severe cold

c) Entry of harmful ultra-violet rays.

Given below is a diagrammatic sketch of the vertical section of human skin.

(a) Label the parts numbered 1 to 9

(b) State one main function of each of the following parts:

1. Part 2.
2. Part 3.
3. Part 4.
4. Part 9.

(c) Name any one of the above parts which has at least three functions.

(d) Part 4 may add to one's good appearances or the "figure". State one example of this function which may be common to both men and women.

The figures A and B given below represent the ways of heat regulation in our body with the help of blood vessels. Study the figures and answer the following questions.

(a) Name the process/condition shown in figures A and B.

(b) During what climatic conditions, do these processes occur in our body?

(c) What colour change do we see in the facial appearance of a person during these situations?

(d) Do these situations occur due to emotional causes? If yes, name them.