Medicine & Health
How do the lungs work?
The lungs work by bringing air in so oxygen can pass into the blood and carbon dioxide can leave it. You breathe in, air fills millions of tiny sacs, and gases swap across their thin walls into and out of nearby blood vessels.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how the lungs works.
Step by step
- 1Breathing in pulls air down into the lungs' tiny sacs (alveoli).
- 2Oxygen passes through the thin sac walls into the blood.
- 3Carbon dioxide passes the other way, to be breathed out.
- 4The diaphragm muscle drives the in-and-out motion.
Frequently asked questions
- How do lungs get oxygen into the blood?
- In the tiny alveoli, oxygen diffuses across thin walls into blood vessels while CO₂ diffuses out.
- What is the diaphragm?
- A dome-shaped muscle below the lungs that contracts to pull air in and relaxes to push it out.
- Why do we breathe out carbon dioxide?
- It's the waste gas from cellular respiration, carried back to the lungs and exhaled.