Respiratory System For Kids - How do we breathe?

How do we breathe?

As you breathe, your chest moves in and out, and up and down.
Inside your chest, there are two flexible, sponge like organs on either side of your heart.

These are your lungs. 

When we inhale (take in air), we breathe in oxygen, a gas which helps to give us energy.
When we exhale (expel air), we breathe out carbon dioxide, a harmful waste gas.
When you breathe in, your lungs fill with air and become larger.
When you breathe out, your lungs become smaller as gas is squeezed out of them.

Breathing in

You inhale air through your nose and mouth.
Inside your nose are tiny hairs that catch dust from the air.
There is also a sticky liquid called mucus that warms and moistens the incoming air and catches many of the germs you breathe in.
The air you breathe in goes down a pipe called the trachea, also known as your windpipe.
From your windpipe, air enters each lung through two tubes called bronchi. 
Each bronchus divides into smaller and smaller tubes, which eventually lead to tiny, elastic sacs called alveoli. 
There are many millions of alveoli in each lung.
When air enters the alveoli, they blow up like tiny balloons. Then oxygen from the air passes through the walls of the alveoli into capillaries, which are very tiny tubelike vessels through which blood flows.

Breathing out

At the same time as oxygen enters your blood, a waste gas passes from the blood into the alveoli.
The air you exhale contains less oxygen and more carbon dioxide.
This is the waste gas your body produces as oxygen breaks apart the chemicals in your food.
When you breathe in, the alveoli in your lungs blow up like tiny balloons.
Oxygen passes into your capillaries. At the same time, carbon dioxide is passed out.

How do we breathe?

You have muscles in your chest that make you breathe.
Some are fixed to your ribs and make your rib cage move in and out. Below your lungs is a strong, flat sheet of muscle called the diaphragm.

 As you breathe in, your diaphragm moves downwards and your rib cage moves out, or expands.
This makes a bigger space for the air that enters your lungs.
As you breathe out, your rib cage and diaphragm squeeze your lungs into a smaller space again.