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๐ฌ Think about it
Your skin covers you on the outside, and a lining covers your mouth, lungs and intestine on the inside. The same kind of tissue does both. How can one tissue protect, absorb and sense? Let us see.
What is epithelial tissue?
- It forms the outer covering of the body (skin).
- It also lines internal organs like the mouth, lungs and intestine.
- Its cells are closely packed with very little space between them.
- It protects, and helps in absorption, secretion and movement of substances.
What are the different types of epithelial tissue?
- Different epithelia are shaped for different jobs.
- Some allow exchange, some protect, some secrete.
- Some help in sensing, and some help in absorption.
| Function | Structure | Location in the body |
|---|---|---|
| Exchange: helps rapid diffusion of liquids and gases | Single layer of thin, flat cells | Lining of blood vessels and lungs |
| Protection: protects underlying tissues from injury, friction and microbes | Many layers of cells; outer cells flat and tightly packed | Skin, mouth and oesophagus |
| Secretion: produces and secretes mucus, enzymes, hormones, sweat, saliva | Cells specialised to release substances; cuboidal or columnar | Salivary glands, sweat glands and stomach lining |
| Sensory functions: smell, taste, sound and balance | Specialised receptor cells with hair-like cilia | Nostrils, taste buds and inner ear |
| Absorption: efficient uptake of nutrients, water, etc. | Single layer of tall, pillar-like cells, often with hair-like structure | Lining of small intestine |
Important Points
- Epithelial tissue covers the body and lines internal organs.
- Its cells are tightly packed, with little space between them.
- Different shapes suit exchange, protection, secretion, sensing and absorption.
โ Test Yourself
-
Where is epithelial tissue found?
View Answer
As the outer skin and as the lining of internal organs. -
Which epithelium suits gas exchange in the lungs?
View Answer
A single layer of thin, flat cells. -
Why are epithelial cells tightly packed?
View Answer
To stop germs entering and to protect underlying tissues. -
Which epithelium lines the small intestine for absorption?
View Answer
A single layer of tall, pillar-like cells.
Important Definitions
- Epithelial tissue — the tissue that covers the body and lines its internal organs.
๐ NCERT Question 3 — Why are the epithelial
Why are the epithelial tissues lining internal organs usually only one or a few cells thick?
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๐ NCERT Question 6 — In each of the
For the given assertion–reason cases (A–D), choose the correct option.
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