oxygen (O2) – carbon dioxide (CO2)
nostrils – mouth – lungs – diaphragm
pharynx – larynx (voice box)
trachea (windpipe) – bronchi


What is the function of the respiratory system?

The respiratory system helps us breathe.
The process of breathing is called respiration.


The air enters through the nostrils or the mouth.
The nostrils are the two external openings of the nose.

Nasal hair in the nostrils filters particles in the air.
It prevents the entry of dust, pollen, viruses, and bacteria.


We breathe in (inhale) oxygen (O2).
We breathe out (exhale) carbon dioxide (CO2).


The lungs get bigger when we breathe in.
The lungs get smaller when we breathe out.


The diaphragm is a strong muscle below the lungs.
It contracts when we breathe in.
It relaxes when we breathe out.

The pharynx opens and the air goes down the trachea.
The trachea is a tube that connects the pharynx and larynx to the lungs.

The trachea is also called the windpipe.
The larynx is also called the voice box.


The air travels down two tubes called bronchi and enters the lungs.
The lungs take in the oxygen to be carried all over the body.


The oxygen passes from the lungs into the blood.
The blood transports the oxygen to the cells.
Cells need oxygen to keep working.


Carbon dioxide passes from the blood into the lungs.


The body eliminates carbon dioxide by breathing out.
When we breathe out, the carbon dioxide leaves the lungs.

The respiratory system – The Dr. Binocs Show
What happens after we breathe?
How does the air travel inside our body?
Source | Peekaboo Kidz

Song – “When You Breathe (Lungs)”
How the lungs take in oxygen to be carried all over your body.
Source | StoryBots

What do the lungs do?
Lesson by Emma Bryce
Animation by Andrew Zimbelman
Source | TED-Ed