Epithelial Tissue: (Structure, Classification and Functions)
(Structure Classification and Functions of Simple and Compound Epithelium)
What is Epithelium?
Ø Epithelium is a tissue system in animals.
Ø Epithelium constitutes the outer layer of body surfaces, linings of the alimentary canal and the walls of hollow structures.
Ø It covers the internal or external surfaces of the body.
Ø Epithelial cells are held together by carbohydrate based cementing materials.
Ø They also possess special junctions between the cells.
Ø The bottom layer of epithelium is rest on the basement membrane.
Ø The basement membrane composed of a network of fibrous proteins particularly rich in collagens.
Ø Epithelial layers are NOT provided with any blood vessels.
Ø The cells of the epithelium obtain nutrients and oxygen by diffusion from the lymphatic vessels.
Ø Nerve endings occur in the epithelial tissues for receiving stimuli.
What are the Functions of Epithelial Tissue?
Ø Epithelium provides protection to the underlying structures.
Ø Protect organs from injuries by external agencies or pressure.
Ø Prevent infection by microorganisms.