by Ms. Perry
The Four Types
A tissue is a group of cells that perform a specific function in the body. There are four main types, epithelial tissue, connective tissue, muscle tissue, and neural tissue.
Epithelial tissue has four main functions. They are to provide physical protection, control permeability, provide sensation, and provide specialized secretions.
Epithelial cells can be specialized to do a number of different things. These include: 1) the movement of fluids over the epithelial surface, therefore providing protection and lubrication. 2) the movement of fluids through the epithelium, to control permeability; and 3) the production of secretions that provide physical protection or act as chemical messengers.
Epithelia has many different specialized types. These can be determined based on the cell shape and the number of cell layers between the base and the exposed surface of epithelium. The classifications of epithelial tissue are simple squamous epithelium, simple cuboidal epithelium, simple columnar epithelium, stratified squamous epithelium, stratified cuboidal epithelium, and stratified columnar epithelium.
Epithelium can be found in many locations in the body. Some of these include the surface of the skin, the lining of ventral body cavities, the lining of the stomach, intestines, and the linings of the nasal cavity, trachea, etc.