Describe various types of epithelial tissues with the help of labelled diagrams.
Explanation The thin lining of cells that forms the covering of surfaces of the body or lines the different cavity of the internal body surface, all these linings are composed of epithelium cells. Skin, mouth, and nasal cavity, even the inner lining of the gastrointestinal tract, are made up of epithelium cells. These epithelium cells perform different functions, such as protection, absorption, secretion, and many more. Based on the arrangement of cells, epithelium tissue is classified into two types, Simple epithelial tissues, and compound or stratified epithelial cells. (i) Simple epithelial tissue: As the name suggests, a single layer of cells functions as a lining for various body cavities and ducts. The simple Epithelium is also classified based on structural modification of cells into three types such as squamous, cuboidal, and columnar. Squamous epithelium: It forms the lining of blood vessels and air sacs of lungs. Cuboidal Epithelium: The lining of the kidney tubule and many duct glands such as thyroid glands, ducts of sweat glands are composed of cuboidal epithelium cells. Cuboidal Epithelium is a single layer of cube-like cells that have equal height and width. Columnar Epithelium: The lining of the stomach, gall bladder, and intestine are made up of these cells. A single layer of tall and slender cells with nuclei located at the base is known as the columnar Epithelium. (ii) Compound or stratified Epithelium consists of more than two layers of cells stacked upon each other. The stratified Epithelium is a multilayer cell that protects against chemical and mechanical stresses. The dry surface of the skin, the moist surface of the buccal cavity, and pharynx are composed of stratified epithelium cells. The stratified epithelium is further classified as stratified squamous epithelial, stratified cuboidal, and stratified columnar epithelium cells.
