The covering or protective tissue in the animal body are epithelial tissues. Epithelial tissue cells are tightly packed and form a continuous sheet. They have only a small amount of cementing material between them and almost no intercellular spaces. Epithelium covers most organs and cavities within the body. It forms a barrier to keep different body systems separate. The skin, the lining of the mouth, the lining of blood vessels, lung alveoli and kidney tubules are all made of epithelial tissue.
Functions of epithelial tissue:
(i) Epithelial cells protect the underlying cells from drying, injury and chemical effects. protect the body from viral or bacterial infections.
(ii) It helps in the absorption of water and nutrients.
(iii) It performs secretary function by secreting useful chemicals like sweat, saliva, enzymes from the food, etc., in the body.
