Define a gland. What are the three kinds of glands ? Give one example of each kind.

Explanation

A cell, a tissue, or an organ which secretes certain useful chemical compounds required for particular functions is called a gland.
Three kinds of glands are :
(i) Exocrine glands (e.g., liver). (ii) Endocrine glands (e.g., thyroid). (iii) Heterocrine glands (e.g., pancreas).