What is the Function of Epithelial Tissue?

Introduction

There are four types of tissues found in animals, viz., Epithelial, Muscular, Connective and Nervous tissue. This article focuses on the types and functions of the epithelial tissues.

Epithelial tissue, commonly referred to as epithelium, is made up of compactly packed cells with very little intercellular matrix. The primary function of the epithelium is to line the outer and inner surfaces of the body.

Types of Epithelial Tissue

The epithelial tissue can be simple or compound. The simple epithelium is a single layer of cells that has the function of lining ducts and cavities. The compound epithelium is multilayered and mostly performs protective function.

The epithelial tissues can be classified on the basis of their cell shapes and functions. The three types of epithelium are –

• Squamous: These are flattened cells with irregular boundaries found mainly in the air sacs of lungs and walls of blood vessels.
• Cuboidal: These are cube shaped cells that are found in the nephrons of kidneys and the ducts of glands.
• Columnar: These are slender and tall cells that have microvilli on their surface. Their nuclei are located at the base of the cell. It is mostly found in the inner linings of the stomach and intestines.

Functions of Epithelial Tissue

Following are the functions of the epithelial tissues:

• Diffusion: The epithelial cells form a diffusion boundary through which exchange of substances keeps taking place between the internal and external environment. The epithelial cells also gain nourishment for themselves through diffusion from the underlying connective tissues.
• Protection: The epithelial tissue lines almost all the surfaces of our body. It protects the bodily tissues from mechanical and physical injury, toxins, radiation and invasion by microorganisms.
• Absorption: The microvilli found on the surfaces on columnar epithelium cells helps in absorption of nutrients and water through the length of the digestive canal.
• Secretion: The columnar and cuboidal cells get specialised for secretion and are then referred to as glandular epithelium.
• Sensation: The sensory cells of the nose, eye and ear that help us in smelling, hearing and seeing are all specialised epithelial cells.

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Also Read:

• Epithelial Tissue and Connective Tissue
• Types Of Plant Tissue System & Their Function
• Tissues – An Overview of Tissues, Its Types and Functions