How many tissues are present

On the basis of their functions, animal tissues are classified into four major types – epithelial tissues, muscular tissues, connective tissues and nervous tissue.

1. Epithelial Tissue:

It is the simplest tissue and protective in nature. The cells of this tissue are tightly packed and they form a continuous sheet. They contain a very little or no intercellular space. It covers most organs and cavities within the body. The skin, the lining of the mouth, the lining of blood vessels, lung alveoli and kidney tubules are all made of epithelial tissue. Anything entering or leaving the body crosses at least one layer of epithelium. As a result, the permeability of the cells of various epithelia plays an important role in regulating the exchange of materials between the body and the external environment and also between different parts of the body. All the epithelium is usually separated from the underlying tissue by an extracellular fibrous basement membrane.

ii. Connective Tissue:

Connective tissue is the binding and supporting tissue of the animal body. Matrix forms the main bulk of this tissue. The cells are loosely spaced and less in number. The matrix may be jelly like, fluid, dense or rigid. The nature of matrix differs in concordance with the function of the particular connective tissue.