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How your lungs work

Respiratory System

The respiratory system is a group of organs and tissues, including the lungs, that work together to help you breathe. The respiratory system’s main job is to move oxygen into your body while removing carbon dioxide.

Why lungs are important

Every cell in your body needs oxygen. Once in the lungs, oxygen moves into the bloodstream and travels through your body. At each cell, oxygen is exchanged for carbon dioxide. Your bloodstream then carries carbon dioxide back to the lungs, where it is removed from the bloodstream and exhaled. This is called gas exchange.

In addition to gas exchange, your respiratory system performs other vital functions including:

  • Warming, filtering and humidifying the air you inhale before it enters your lungs (your nose is better at this than your mouth).
  • Coughing and sneezing to protect your body from harmful substances.
  • Supporting your sense of smell.
  • Supporting your voice, as you breathe air through your vocal cords to speak.

How your lungs work

Inhaling and exhaling: To breathe in, you mainly use your diaphragm muscle, which is just below your rib cage. Your diaphragm tightens and flattens, allowing you to suck air into your lungs. Muscles between your ribs also help you breathe in. To breathe out, your diaphragm and rib cage muscles relax.

From your nose to your windpipe: You inhale air through your nose and mouth to get the oxygen your body needs. The mucus membranes in your mouth and nose warm and moisten the air and trap particles (like dirt and dust). The air passes through your throat into the windpipe (trachea). The windpipe divides into the left and right bronchi. Each bronchus divides again and again, becoming narrower and narrower.

Bunches of balloons: Your smallest airways end in the alveoli, which are small, thin air sacs arranged in clusters like bunches of balloons. When you breathe in by enlarging the chest cage, the “balloons” expand as air rushes in. When you breathe out, the “balloons” relax and air moves out of the lungs.

Oxygen in and carbon dioxide out: Tiny blood vessels surround each of the 300 million alveoli in the lungs. Oxygen moves across the walls of the air sacs, is picked up by the blood and carried to the rest of your body. The waste gas, carbon dioxide, passes into the air sacs from the blood and is breathed out.