Lungs and Breathing

Core Idea

You breathe in air to get oxygen, which your body needs to make energy. Your lungs are two spongy organs in your chest that take oxygen from the air and put it into your blood. When you breathe out, you push out a waste gas called carbon dioxide. You breathe all day and all night without even thinking about it.

How It's Best Learned

Take deep breaths and notice your chest rising and falling. Breathe on a cold window or mirror and see the fog (that is water and carbon dioxide from your lungs). Count how many breaths you take in one minute at rest, then after exercise. Compare the numbers.

Common Misconceptions

• Children may think they breathe in only oxygen (air is mostly nitrogen; oxygen is about 21%).
• Some children think they breathe out oxygen too (they breathe out mostly carbon dioxide and nitrogen).
• Children may not realize that breathing happens automatically even when they are not thinking about it.

Explainer

Take a deep breath right now. Feel your chest rise as air flows in through your nose or mouth, down your throat, and into your lungs. Your lungs are two spongy, balloon-like organs inside your rib cage, one on each side of your heart. Their job is to get oxygen out of the air and into your blood.

Here is how it works. The air you breathe in contains a gas called oxygen. Your body needs oxygen the way a fire needs air — without it, your cells cannot make energy. When air fills your lungs, oxygen passes through the thin walls of tiny air sacs and enters your blood. Your heart then pumps that oxygen-rich blood to every part of your body.

While your body uses oxygen, it produces a waste gas called carbon dioxide. Your blood carries carbon dioxide back to your lungs, and when you breathe out, you push that waste gas out of your body. So breathing is really a swap: oxygen in, carbon dioxide out. Every breath you take makes this trade.

The amazing thing is that you do not have to think about breathing. Your brain handles it automatically. Right now, while you are reading this, your brain is telling your lungs to breathe in and out about 15 to 20 times per minute. When you run or play hard, your brain speeds up your breathing because your muscles need more oxygen. When you rest or sleep, your brain slows it down because your body needs less. You can choose to hold your breath for a little while, but eventually your brain will take over and make you breathe again — because breathing is too important to leave to chance.