The path of air
Breathe in slowly through your nose. Air then moves along a short path inside you.
- Nostrils: hairs and mucus catch dust.
- The throat leads to the windpipe.
- Rings of cartilage, a firm bendy tissue, keep the windpipe open.
- In the lungs, the tubes branch again and again.
- Each tiny tube ends in alveoli.
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Lift the ribs and flatten the diaphragm. Watch the air arrow.
The rule
Air passes through the nostrils, throat and windpipe. Then it passes down smaller and smaller tubes to the alveoli.
The alveoli are tiny sacs at the ends of the tubes. They are where gases swap with the blood.
Breathing needs muscles. The ribs and the diaphragm make the chest cavity bigger and smaller. The diaphragm is a sheet of muscle under the lungs. The chest cavity is the space inside the ribs.
When you breathe in, the ribs lift and the diaphragm flattens. The cavity gets bigger, so air flows in. When you breathe out, the ribs return and the diaphragm curves up. The cavity gets smaller, so air flows out.
| Ribs | Diaphragm | Chest cavity | Air | |
|---|---|---|---|---|
| In | Lift | Flattens | Bigger | Flows in |
| Out | Return | Relaxes and curves up | Smaller | Flows out |