Epi=surface
Thelial=
The epithelium vapor forms the tissue covering of external and internal surface of the body. There are two types of epithelia tissue: simple and compound epithelium
a.Simple Epithelium
It is made up of a single layer of identical cells which located on the surfaces of absorptive and secretory cells. They are:
It has thin flatten cells with little cytoplasm that surround the nucleus
Location: key red tube; alveda lining of lung; endothelium
Function: diffusion of materials on the basement membrane that links to connective tissue. It replace the new epithelium from the old one since it carries out mitosis. It covers other tissues and protect them from injuries.
It also consists of a single layer of cuboidal cells whose free surface is polygonal in shape. These cells fit together like a honey comb
Location: they from the linings of many ducts such as the salavary, pancreatic, mammary and collecting ducts. Their cells are non secretory.
Function: they help mainly in absorption of micro molecule and transport of fluid.
There are also made up of a single layer of cells which are narrow and elongated with each nucleus located at the basal end. They may also contain secretory goblet cell
Location: they line the stomach and secrete nucleus from the goblet cells which protect the stomach from auto digestion. It also lines the intestines and contains microvilli at the surface of each cell which increase the surface area of absorption and secretory
Function: they are important for absorption and secretion of material
- Pseudo-stratified epithelium
It looks stratified because the nuclei are located at one or more level within the cells of the tissue. These cells vary in shape and lay on the same basement membrane. The cells also have cilia which beat and move
Location: found in the urinary tract and trachea
Functions: the goblet cells contain and secrete mucus which traps dust particles and microbes from the inhaled air.
