What happens when I breathe?

When you breathe in, the air first travels into your mouth and nose. From there it goes into your trachea—also called your windpipe—and then travels through tubes called airways, all the way down into your lungs. Air contains oxygen, and once inside the lungs, the oxygen can travel through the bloodstream to wherever in the body it’s needed.

When you breathe, the air enters the body through the nose or the mouth. It then travels down the throat through the larynx (voice box) and trachea (windpipe) and goes into the lungs through tubes called main-stem bronchi.

One main-stem bronchus leads to the right lung and one to the left lung. In the lungs, the main-stem bronchi divide into smaller bronchi and then into even smaller tubes called bronchioles. Bronchioles end in tiny air sacs called alveoli.

Intermountain Registered Dietitians
Nutrition & Dietetics Specialist

When you breathe, you absorb oxygen from the air. You also get rid of carbon dioxide, a gas that’s produced when your body’s cells use up oxygen. This exchange takes place in your lungs, two sponge-like organs in your chest.

  • When you take a breath in, air flows down your throat and windpipe (trachea).
  • From the trachea, air flows into two large, tubular airways (bronchial tubes). The bronchial tubes branch as they extend into your lungs.
  • From the bronchial tubes, air goes deeper into the lungs through smaller and smaller branches. These smaller airways are called bronchioles.
  • At the end of this maze of little branches are tiny air sacs called alveoli. These sacs take oxygen from the air you breathe and pass it into your bloodstream. They also collect carbon dioxide from the bloodstream for you to breathe out.
  • When you breathe out, air—now carrying carbon dioxide—travels out of your lungs the way it came in.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.