Breathing brings oxygen to the body — Biology, 7–10 years
When we breathe in, oxygen enters the lungs and then the blood. When we breathe out, carbon dioxide leaves. This exchange helps cells release energy from food.
Air travels to the lungs
Breathing is more than moving air in and out of the nose or mouth. The lungs have many tiny air spaces surrounded by blood vessels. Oxygen crosses into the blood there, while carbon dioxide crosses out to be breathed away.
Why do cells need oxygen?
Cells need energy to move, grow and repair the body. They get much of this energy by using oxygen to break down nutrients from food. Breathing solves the problem of delivering oxygen to cells and removing the carbon dioxide made during this work.
Worked example: after running
Run for one minute, then notice your breathing. Your leg muscles are working harder, so their cells need more oxygen and make more carbon dioxide. Your brain makes you breathe faster; the lungs take in more oxygen and remove the extra carbon dioxide.
Trap: breathing is only about oxygen
Because oxygen is important, it is natural to focus only on breathing it in. But breathing out matters just as much: it removes carbon dioxide, a waste gas made by working cells. If it built up, the body would not work properly.
Breathing in daily life
Athletes watch breathing because muscles need more oxygen during exercise. Doctors measure breathing to check the lungs, and inhalers can help some people move air more easily. Clean air matters because lungs exchange gases with the air around us.
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