Breathing is what we do to get oxygen into our blood and take carbon dioxide from it.

Breathing happens through the lungs, the bones in our chest and a flexible rubbery sheet called the diaphragm.

When we breathe in, the diaphragm moves down and the chest moves out, creating a kind of vacuum in the lungs. This sucks air in from nose and mouth. The surface of the lungs then extracts oxygen from the air, while carbon dioxide seeps from the walls of the lungs into the air. We never take all of the oxygen from the air, by the way, which is why you can give mouth-to-mouth resuscitation.

Then we breathe out (exhale) by bringing the diaphragm up and pulling the chest bones in. This pushes the air out ready for the cycle to begin all over again.