Page 17 - Viva ICSE Science 5 : E-book

Functions

• The red blood cells carry oxygen from the lungs
Did You Know!
to diff erent parts of the body. They also help to
A blood clot is a thickened mass
remove carbon dioxide from the body.
of blood formed by platelets.
• The white blood cells help to fi ght infection. Clots form to stop bleeding in
case of an injury.
They destroy germs which may have entered
the body.

• Platelets help in clotting of blood.

• The liquid portion of the blood dissolves and transports nutrients and other

substances that are required by the diff erent parts of the body. Similarly, it carries
away the waste material from all parts of the body.

• Blood helps in maintaining temperature of the body and helps us survive through
various seasons.

TIME TO REVISE

Fill in the blanks.
1. ___________ system helps in digestion of food.

2. The human heart is ___________-chambered.
3. The ___________ allow the fl ow of blood in one direction only.
4. The red blood cells carry ___________ from the lungs to diff erent parts of the body.

Blood vessels

Inside the body, blood fl ows through a network of tubes and channels. These tubes and
channels are known as blood vessels.

Structure and functions of blood vessels

There are three types of blood vessels—arteries, veins and capillaries. Let us learn about
the structure and function of each type.

Arteries

The main function of the arteries is to carry oxygen-rich blood from the heart to diff erent
body parts. Arteries are deep seated except at some places like the wrist and along the
side of the neck where these are close to the skin. They have thick elastic walls. They

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