One of the simplest animal tissues is epithelium. Epithelium is a lining tissue. The covering or protective tissues in the animal body are epithelial tissues. Epithelium covers most organs and cavities within the body. Epithelial tissues forms a barrier to keep different body systems separate. Epithelial tissue cells are tightly packed and form a continuous sheet. They have only a small amount of cementing material between them and almost no intercellular spaces (Watch Epithelial Tissues Video to learn more).
Different types of epithelial tissues are :
(a) Squamous epithelium (b) Cuboidal epithelium
(c) Columnar epithelium (d) Ciliated epithelium
(e) Cuboidal epithelium (f) Glandular epithelium
Epithelial tissue can be divided into two groups depending on the number of layers of which it is composes. Epithelial tissue which is only one cell thick is known as simple epithelium. If it is two or more cells thick such as the skin, it is known as stratified epithelium.
Different epithelia show differing structures that correlate with their unique functions. For example, in cells lining blood vessels or lung alveoli there is a simple flat kind of epithelium. This is called the simple squamous epithelium. Simple squamous epithelial cells are extremely thin and flat and form a delicate lining. The oesophagus and the lining of the mouth are also covered with squamous epithelium. The skin, which protects the body, is also made of squamous epithelium. Skin epithelial cells are arranged in many layers to prevent wear and tear. Since they are arranged in a pattern of layers, the epithelium is called stratified squamous epithelium.
Where absorption and secretion occur, as in the inner lining of the intestine, tall epithelial cells are present. This columnar epithelium facilitates movement across the epithelial barrier. These cilia can move, and their movement pushes the mucus forward to clear it. This type of epithelium is thus ciliated columnar epithelium. Cuboidal epithelium forms the lining of kidney tubules and ducts of salivary glands, where it provides mechanical support.
Epithelial Tissues Video
Useful for CBSE, ICSE, NCERT & International Students
Grade : 9
Subject : Biology
Lesson : Tissues
Topic: Epithelial Tissue Video
Visit www.oztern.com to find personalized test preparation solutions for Pre Medical – AIPMT, AIIMS, JIPMER, State, Pre Engineering – IIT JEE, JEE MAIN, BITSAT, State and Foundations – Class 6 to 10.