Page 28 - ICSE Science 3 : E-book

The hair and the mucus trap dust particles and germs that enter our nose during
breathing in. This prevents the entry of dust and germs into the lungs.

Windpipe: It is an air passage in the body that carries air from the nose to the

lungs. Windpipe is also called throat or trachea.

Lungs: These are the main organs of the respiratory
Did You Know!
system. We have a pair of lungs located in the chest
The left lung of a human
cavity. These are the spongy bag-like structures body is slightly smaller than

protected by the ribcage. They absorb oxygen from the right lung.
the inhaled air and remove carbon dioxide through

the exhaled air.

Process of breathing

Breathing is the process of
taking in oxygen into the lungs ribs move ribs move
outwards inwards
and giving out carbon dioxide.
When we breathe in through

our nose, the air moves down
through the windpipe and

reaches the two lungs. In diaphragm diaphragm
moves moves
the lungs, the oxygen gets downwards upwards

absorbed from the inhaled air inhalation exhalation
and carbon dioxide is exhaled. Mechanism of breathing in humans

As we breathe in and out, a special organ called diaphragm moves up and down

below the lungs. The diaphragm helps our lungs to expand and contract while we

inhale and exhale, respectively.

ACTIVITY TIME
Working Model of the Respiratory System

Aim:
To observe and learn the functioning of lungs and diaphragm during the process of
inhalation and exhalation
You Need:
A two-litre empty soft drink bottle with a cap, 1 large balloon, 2 small balloons, tape, a
Y-shaped glass tube or a hose connector, scissors, string, rubber bands

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