How Lungs Work

Lungs are part of the respiratory system, a group of organs and tissues that work together to help you breathe.
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Your lungs are an essential part of the respiratory system that work together to help you breathe. Learn how your lungs work and how to keep your lungs and yourself healthy.

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You can live for two weeks without food, two days without water, but only two minutes without air.

Every single organ in your body is made up of cells, and they all require oxygen for you to live.

Your lungs are part of the respiratory system, a group of organs and tissues that work together to help you breathe.

The respiratory system’s main job is to transport oxygen and remove extra carbon dioxide. Let’s start by looking at the components of this important body system.

The diaphragm is the main muscle for breathing. This dome-shaped wall of muscle does most of the breathing work by expanding and contracting the chest to draw air in and out of your lungs.

When the diaphragm contracts, air is pulled into your airway through your nose or mouth.

Air then travels down your airway, or trachea, dividing into your right or left lung via the bronchi.

The bronchi then separate into small tubes called bronchioles. Like tree branches, bronchioles divide into thousands of even smaller passages.

At the end of each bronchiole is a cluster of little air sacs called alveoli.

Alveoli are wrapped in tiny blood vessels called capillaries.

The air you breathe in fills these air sacs with oxygen-rich air. This is where the exchange of gases occurs.

Carbon dioxide is the gas we naturally produce and need to remove when our bodies use oxygen for energy. At this point, the capillaries are packed with carbon dioxide, and the alveoli are full of oxygen.

Oxygen and carbon dioxide pass through these capillaries into the air sacs. As oxygen crosses over into the capillaries, the red blood cells capture it, while the carbon dioxide is unloaded into the lungs to be removed.

The oxygen-rich hemoglobin is transported throughout the body and the lungs exhale the carbon dioxide.

This never-ending cycle keeps all parts of your body supplied with oxygen.

Your lungs have developed a few defenses against constant exposure to particles in the air that you breathe in.

Your bronchial tubes are lined with cilia - thin, little hairs - and coated with mucus…

…to capture these unwelcome intruders and sweep the mucus-coated particles back up to your throat until you cough, sneeze, or swallow to get rid of them.

All day, every day, your lungs repeat this critical job of keeping your body supplied with the oxygen you need. That's why we say, "When you can't breathe, nothing else matters."

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Why Are Lungs Important?

Every cell in your body needs oxygen to live. The air we breathe contains oxygen and other gases. The respiratory system's main job is to move fresh air into your body while removing waste gases.

Once in the lungs, oxygen is moved into the bloodstream and carried through your body. At each cell in your body, oxygen is exchanged for a waste gas called carbon dioxide. Your bloodstream then carries this waste gas back to the lungs where it is removed from the bloodstream and then exhaled. Your lungs and respiratory system automatically perform this vital process, called gas exchange.

In addition to gas exchange, your respiratory system performs other roles important to breathing. These include:

  • Bringing air to the proper body temperature and moisturizing it to the right humidity level.
  • Protecting your body from harmful substances. This is done by coughing, sneezing, filtering or swallowing them.
  • Supporting your sense of smell.

The Parts of the Respiratory System and How They Work


  • SINUSES are hollow spaces in the bones of your head above and below your eyes that are connected to your nose by small openings. Sinuses help regulate the temperature and humidity of inhaled air.
  • The NOSE is the preferred entrance for outside air into the respiratory system. The hairs lining the nose's wall are part of the air-cleaning system.
  • Air also enters through the MOUTH, especially for those who have a mouth-breathing habit, whose nasal passages may be temporarily blocked by a cold, or during heavy exercise.
  • The THROAT collects incoming air from your nose and mouth then passes it down to the windpipe (trachea).
  • The WINDPIPE (trachea) is the passage leading from your throat to your lungs.
  • The windpipe divides into the two main BRONCHIAL TUBES, one for each lung, which divides again into each lobe of your lungs. These, in turn, split further into bronchioles.

Lungs and Blood Vessels

  • Your right lung is divided into three LOBES, or sections. Each lobe is like a balloon filled with sponge-like tissue. Air moves in and out through one opening—a branch of the bronchial tube.
  • Your left lung is divided into two LOBES.
  • The PLEURA are the two membranes, actually, one continuous one folded on itself, that surround each lobe of the lungs and separate your lungs from your chest wall.
  • Your bronchial tubes are lined with CILIA (like very small hairs) that move like waves. This motion carries MUCUS (sticky phlegm or liquid) upward and out into your throat, where it is either coughed up or swallowed. Mucus catches and holds much of the dust, germs, and other unwanted matter that has invaded your lungs. You get rid of this matter when you cough, sneeze, clear your throat or swallow.
  • The smallest branches of the bronchial tubes are called BRONCHIOLES, at the end of which are the air sacs or alveoli.
  • ALVEOLI are the very small air sacs where the exchange of oxygen and carbon dioxide takes place.
  • CAPILLARIES are blood vessels in the walls of the alveoli. Blood passes through the capillaries, entering through your PULMONARY ARTERY and leaving via your PULMONARY VEIN. While in the capillaries, blood gives off carbon dioxide through the capillary wall into the alveoli and takes up oxygen from air in the alveoli.

Muscles and Bones

  • Your DIAPHRAGM is the strong wall of muscle that separates your chest cavity from the abdominal cavity. By moving downward, it creates suction in the chest, drawing in air and expanding the lungs.
  • RIBS are bones that support and protect your chest cavity. They move slightly to help your lungs expand and contract.

Keeping Lungs Healthy

Lung capacity declines as you age. Keep your lungs healthy by taking good care of yourself every day. Eat a balanced diet, exercise and reduce stress to breathe easier. Get more tips for healthy lungs.

Page last updated: September 29, 2023

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