Tissues — Science STD 9 — Question

Epithelium is the simplest tissue. It is the protective tissue of the animal body in which the cells are tightly packed having no intercellular matrix. Epithelial cells lie on a delicate non-cellular basement membrane which contains a special form of matrix protein, called collagen. These tissues perform the function of excretion, secretion and absorption. Depending upon the shape and functions of the cells.

The epithelial tissue is of various types:

1. Squamous: The cells are flat and polygonal and are arranged as tiles. These tissues occur in skin, lining of alveoli of lungs, blood vessels etc. Its function includes protection, diffusion and osmosis.

2. Cuboidal: The cells are cube like. These occur in glands, germinal layer of ovary, kidney tubules etc. Its function is secretion and absorption.

3. Columnar: The cells are pillar or column like resting on a thin membrane. Such tissues occur in the lining of stomach, intestine etc. Its function includes protection, absorption and secretion.

4. Ciliated: It has cuboidal, columnar cells with fine hair like structures called cilia. It is present in the lining of respiratory tract, fallopian tube, nephron etc. Its function is protection, spreading of mucus and motion of gases and liquids by cilia.

5. Glandular: The cells are cubical. These can be branched or unbranched. Such tissues are present in glands. Its main function is secretion.