Mon Prof Augmenté
How We Breathe In
Age 13 · Biology
When you breathe in, the diaphragm under your lungs tightens and flattens while your ribs lift up and out. This makes your chest bigger, so the pressure inside your lungs drops and air rushes in.
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Age 13: open this week
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In the picture
- Windpipe (trachea): the tube that carries air down to the lungs
- Lungs: they expand and fill with air as the pressure inside them falls
- Ribs: lifted up and outward by the muscles between them, widening the chest
- Diaphragm: contracts, flattens and moves down, making the chest deeper
Examples
- Before diving underwater, you take a deep breath and can feel your chest rise and your belly push out.
- When you pull the plunger of a sealed syringe back, the space gets bigger and air rushes in through the tip, just like air entering your lungs.
Key takeaways
- Breathing in: diaphragm contracts and flattens, ribs move up and out, chest volume increases.
- Bigger volume means lower pressure in the lungs, so air flows in from outside.
Quiz: How We Breathe In (Age 13)
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When you breathe in, what does your diaphragm do?
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When your chest gets bigger, what happens to the pressure inside your lungs?
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How do your ribs move when you breathe in?
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