Page 41 - ACTIVE SCIENCE 4 TOC

C irculatory System

Our body has many organs which help us to do different things. The circulatory
system comprises heart, blood and blood vessels which help in transporting the

substances inside our body.

Heart
The heart is about the size of a closed fist. It is located between
the lungs, a little towards the left side of the body. It is a muscular

organ which pumps blood, oxygen and other nutrients to every
little part of the body. It also receives blood from all the organs
of the body.

Blood Vessels Heart

These are thin tube-like structures that form a

network from the heart through the entire body.
These tubes carry blood from the heart to all the
parts of the body and then back to the heart again.
Heart The blood vessels are of three types:

a. Arteries : They carry oxygenated blood
from the heart to all the parts of the body.
Blood
Vessels b. Veins : They carry deoxygenated blood or
blood with carbon dioxide from different
parts of the body to the heart.
Arteries
c. Capillaries : Arteries branch out into

arterioles, i.e., smaller and thinner blood
Veins
vessels. These are further grouped into
smaller blood vessels called capillaries.

Capillaries are the smallest blood vessels
that help in the exchange of gases, water

and nutrients between the blood and
Circulatory System tissues.

Blood

Blood is a red-coloured fluid. It flows through blood vessels from the heart to all
parts of the body and then back to the heart. It transports the nutrients absorbed
from the food, oxygen, carbon dioxide and water inside the body. It also passes the

waste produced in the body to the excretory system for removal.

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