Epithelial tissue is the tissue that covers surface areas of the body. There are three different types of epithelial tissue. Taken together they are called the epithelium. In any given region of the body, the epithelial tissue is arranged in certain ways, with varying layers of cells. The aggregate is collectively referred to as the epithelium.

The three types of epithelial tissue are: covering and lining tissue, glandular tissue, and sensory tissue. The covering and lining epithelia are associated with, as in these three examples, the skin, the lining of the Gastrointestinal tract, and the lining of the respiratory tract. Their location determines the function of these cells. Again using the above examples, the skin epithelia is a protective layer, the epithelial tissue of the Gastrointestinal tract is concerned with the absorption of nutrients, and the epithelial tissue of the lung alveoli...