What is Epithelial Tissue Class 9

Epithelial tissue is a special type of tissue that forms the outer covering of the body (skin), and it also lines the internal organs, such as the mouth, lungs, blood vessels, and intestine. It is made up of closely packed cells with little space between them.

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It acts as a protective barrier against the entry of germs and helps to reduce the excess water loss. It also helps in the absorption, secretion, and movement of substances.

You can read more on the testbook of the Class 9 NCERT book.

Function of Epithelial Tissue

Epithelial tissue performs many important functions in our body and also helps to coordinate with organs.

1. It helps in the rapid diffusion of liquid and gases in our body. For example, the lining of tissue in the blood vessels and lungs.

2. It acts as a protective underlying tissue from an injury and friction and prevents the entry of pathogens microorganism.

3. Secretion: It produces and secretes mucus, enzymes, hormones, and sweat on the skin and saliva on the mouth.

4. Sensory: It helps us to perform sensory functions like smell, taste, and sound.

5. Absorption: It balances the uptake of nutrients, water balance, etc.

Structure of Epithelial Tissue

1. It is a single layer of thin, flat cells. It is composed of many layers of cells. The outer cells are flat and tightly packed.

2. Those cells are specialized for producing and releasing many substances, like the salivary gland produce saliva. Sweat glands produce sweat, and the stomach produces mucus.

3. These cells, or specialized receptor cells, look like hair-like cilia. For example: nostrils in the nose and taste buds on the tongue.

4. Some epithelial tissue is a single layer of tall, pillar-like cells of a hair-like structure. For example: lining of the small intestine.

Types of Epithelial Tissue

According to NCERT class 9, there are 5 types of epithelial tissue that are found in our body and perform different functions.

Type	Shape	Main Function	Example
Simple Squamous	Flat	Diffusion and filtration	Alveoli, blood vessels
Cuboidal	Cube-shaped	Secretion and absorption	Kidney tubules
Columnar	Tall	Absorption and secretion	Small intestine
Ciliated Columnar	Columnar with cilia	Movement of mucus or eggs	Trachea, Fallopian tube
Stratified Squamous	Many layers	Protection	Skin, mouth
Glandular	Secretory cells	Produces hormones and enzymes	Sweat glands, salivary glands