The LungsHow air becomes oxygen in the blood, and the numbers behind a breath.Body & healthOne breath, from nose to bloodstream.1Nose and mouthAir is warmed, moistened and filtered before it goes further.2Trachea and bronchiThe windpipe splits into two bronchi, then branches about 23times.3BronchiolesThe narrowest airways. Asthma constricts these.4AlveoliAbout 300 million tiny sacs, one cell thick, wrapped in capillaries.5ExchangeOxygen diffuses in, carbon dioxide diffuses out, driven bypressure differences alone.THE NUMBERS12–20 breaths per minute at restAbout 500 ml per breathAlveolar surface area: roughly 70 m²The diaphragm does the work. It contracts and flattens, lowering thepressure so air is pulled in.The Lungslearnposters.com
The Lungs — printable health wall chart from LearnPosters. Free vector PDF, US Letter and A4.

The Lungs, step by step

One breath, from nose to bloodstream.

  1. Nose and mouthAir is warmed, moistened and filtered before it goes further.
  2. Trachea and bronchiThe windpipe splits into two bronchi, then branches about 23 times.
  3. BronchiolesThe narrowest airways. Asthma constricts these.
  4. AlveoliAbout 300 million tiny sacs, one cell thick, wrapped in capillaries.
  5. ExchangeOxygen diffuses in, carbon dioxide diffuses out, driven by pressure differences alone.

The numbers

  • 12–20 breaths per minute at rest
  • About 500 ml per breath
  • Alveolar surface area: roughly 70 m²

The diaphragm does the work. It contracts and flattens, lowering the pressure so air is pulled in.

Questions about the The Lungs poster

What’s on the The Lungs poster?
5 numbered steps, with a full worked run-through. One breath, from nose to bloodstream. Nose and mouth — Air is warmed, moistened and filtered before it goes further.; Trachea and bronchi — The windpipe splits into two bronchi, then branches about 23 ti…; Bronchioles — The narrowest airways. Asthma constricts these.; Alveoli — About 300 million tiny sacs, one cell thick, wrapped in capillaries.; Exchange — Oxygen diffuses in, carbon dioxide diffuses out, driven by pressure differ…. The diaphragm does the work. It contracts and flattens, lowering the pressure so air is pulled in.
Who is the The Lungs poster for?
The Lungs belongs to the Body & health section rather than to a school year, because health is not something one grade owns. Anyone learning anatomy can pin it up — a beginner, a student mid-course, or someone revising years later.
When should you use the The Lungs poster?
The exchange happens in the alveoli. Everything above them is plumbing. A wall chart earns its place by being glanceable from where the work is happening, so The Lungs belongs on the wall where that health work actually happens, within glancing distance, rather than filed away.
What other posters go with The Lungs?
Blood, Blood Types and The Body Systems sit alongside The Lungs in the Body & health section. Printed together they make a wall rather than a single sheet, which is how a reference set actually gets used.BloodBlood TypesThe Body Systems
Is the The Lungs poster free to download and print?
Yes. The Lungs downloads as a free PDF with no account, no email and no watermark, like everything else in the Body & health section. Print as many copies as you like for a home, a classroom, a library or a tutoring group; reselling the file is the only thing the licence rules out.Read the licence
What size does the The Lungs poster print at?
The Lungs is a vector PDF laid out for US Letter, and prints on A4 with Fit to page — the same file, no separate download. Because every mark on it is drawn rather than photographed, it stays sharp enlarged to A3, A2 or A1 at a copy shop. Colour carries emphasis only, so a greyscale print of The Lungs loses nothing.Printing guide

Related posters

Charts that sit alongside The Lungs on the same wall.

Browse every Body & health poster, or start from the full catalogue.