Monday, February 29, 2016
ANIMAL TISSUES- EPITHELIAL TISSUE-TEXT
On the basis of their function, animal tissues are of four major types. They are epithelial tissue, connective tissue, muscle tissue and nervous tissue.
Let us examine the structure the structure and functions of these four kinds of tissues in animals ( including man).
Epithelial tissue: epithelial tissue forms a covering over the surface of the body as well as on the outside and inside of several internal organs example skin is an epithelial tissue on the outer side of the body. Lining of the digestive tract is a covering of epithelial cells on the internal organ.
Epithelial cells perform several functions- they offer protection, produce structure like hair, nails, feather and horns, in the form of gland cells, they secrete a variety of chemical and may involve in receiving external stimuli.
Cells in the epithelial are very close to each other and are joined together by a cementing substance. Epithelial cells occur in various shapes, flat, cube like, long and cylindrical.
Epithelialcells lining the digestive and respiratory system of several animals have hair like projections called cilia. They help in moving the food particles or mucus.
Epithelial cells may be present in a single layer or may occur in multiple layer stratified epithelium.