How do my lungs work?

Your lungs make oxygen available to your body and remove other gases, such as carbon dioxide, from your body. This process takes place 12 to 20 times per minute.

When you inhale through your nose or mouth, air travels down the pharynx (back of the throat), passes through your larynx (voice box) and into your trachea (windpipe). Your trachea is divided into 2 air passages called bronchial tubes. One bronchial tube leads to the left lung, the other to the right lung. For the lungs to perform their best, the airways need to be open during inhalation and exhalation and need to be free from inflammation (swelling) and abnormal amounts of mucus.

The right lung has 3 sections called lobes and is a little larger than the left lung, which has 2 lobes. The bronchial tubes divide into smaller air passages called bronchi, and then into bronchioles. The bronchioles end in tiny air sacs called alveoli, where oxygen is transferred from the inhaled air to the blood.

Lungs, Bronchial tube, Alveoli and Cilia

After absorbing oxygen, the blood leaves the lungs and is carried to the heart. The blood then is pumped through your body to provide oxygen to the cells of your tissues and organs. When cells use oxygen, carbon dioxide (CO 2 ) is produced and transferred to the blood. Your blood carries the CO 2 back to your lungs and it is removed when you exhale.

Your respiratory system prevents harmful substances from entering the lungs by using:

  • Small hairs in your nose act as an air-cleaning system and help filter out large particles;
  • Mucus produced in the trachea and bronchial tubes to keep air passages moist and aid in intercepting dust, bacteria and other substances;
  • The sweeping motion of cilia (small hairs in the trachea) to keep air passages clean. If substances such as cigarette smoke are inhaled, the cilia stop functioning properly.

Healthy lungs are made of a spongy, pinkish-gray tissue. Lungs that have become polluted with harmful carcinogens (substances that cause cancer) or carbon particles appear to have blacked spots on the surface. Healthy lungs are elastic so they can expand when you exhale. In contrast, a disease like emphysema causes the lungs to lose their elasticity.

When a person's lung can no longer expand properly or transfer oxygen to the blood, that person has difficulty breathing and tires easily.

Last reviewed by a Cleveland Clinic medical professional on 09/14/2018.


  • American Lung Association. Your Lungs: How Lungs Work. ( Accessed 4/11/2019.
  • U.S. Department of Health & Human Services. National Institutes of Health. National Heart Lung and Blood Institute Diseases and Conditions Index. Lung Diseases: How the Lungs Work. ( ( Accessed 4/11/2019.

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