The tight covering
Epithelial tissue covers and lines the body.
A wall with gaps
Suppose a boundary wall around a school has big gaps between the bricks.
What would a body covering with big gaps between its cells let through?
What this lesson covers
The idea
Epithelial tissue covers the body and lines internal organs; its closely packed cells, with very little space between them, prevent entry of germs, reduce water loss and help in absorption, secretion and movement of substances.
A wall with gaps
Suppose a boundary wall around a school has big gaps between the bricks.
What would a body covering with big gaps between its cells let through?
- Germs and water
- Nothing at all
- Only air
Close the gaps
Germs are falling on the cells. Slide the cells together to close the gaps.
Epithelial tissue
Epithelial tissue forms the outer covering of the body (skin) and lines the internal organs such as the mouth, lungs, blood vessels and intestine. It is made of closely packed cells with very little space between them. This structure prevents the entry of germs, reduces water loss, and also helps in the absorption, secretion and movement of substances.
Notes
Epithelial tissue covers the body and lines internal organs. Its closely packed cells keep out germs and reduce water loss; they also help in absorption, secretion and movement of substances.
Check yourself
Epithelial tissue…
Why are epithelial cells closely packed?
Which of these is not done by epithelial tissue?
- carries messages along long fibres. That is nervous tissue.
- makes the body move. That is muscular tissue.
- covers the body and lines internal organs — correct. Yes.
- It keeps germs out and reduces water loss — correct. Yes.
- It lets germs pass easily. The opposite is true.
- It makes the tissue hard like bone. Bone is hard because of its matrix.
- Absorption of substances. Epithelial tissue helps in absorption.
- Secretion of substances. Epithelial tissue helps in secretion.
- Carrying messages along nerves — correct. Yes. That is nervous tissue.