11 Facts About the Lungs

Every cell in your body needs oxygen to function properly. Your lungs are crucial in achieving this goal—once you take air into your lungs, oxygen enters the bloodstream and moves through your body. Each cell makes a trade, exchanging oxygen for carbon dioxide, which your blood then transports back to the lungs. When you exhale, you’re actually expelling carbon dioxide (CO2), nitrogen, and water vapor. Altogether, your lungs are a highly efficient machine—and they do a lot more than you might think.

1. Taking in oxygen is only one of your lungs’ important jobs. 
2. Bronchial tubes connect your lungs to your throat and mouth.
3. Your lungs are more like buckets than balloons.
4. Lungs are huge.
5. Without mucus, your lungs would dry up. 
6. Whatever you inhale goes from your lungs to your brain. 
7. Coughing isn’t always bad for your lungs.
8. Asthma isn’t just one disease affecting lung function.
9. Exercise can make asthma—and your lung function—better.
10. You can get lung cancer even if you’ve never smoked.
11. Breakthroughs in lung cancer treatments have improved survival rates. 

Taking in oxygen is only one of your lungs’ important jobs. 

Yes, you need oxygen to live, but if you didn’t expel the carbon dioxide in your lungs, you would die. Carbon dioxide acts like an acid in the body and is generated by muscle action, Wendie Howland, a nurse with Howland Health Consulting in Massachusetts, told Mental Floss in 2017. “Your body operates optimally at a fairly narrow pH range, and when you generate extra CO2 by, say, running up the stairs, you bring your pH into the normal range almost immediately by excreting CO2 by breathing deeply.” So exhaling that more toxic CO2 is as important as taking in oxygen.

Bronchial tubes connect your lungs to your throat and mouth.

So how does your body make this happen? Bronchial tubes connect your lungs to airways and are lined with little hairs called cilia that move in wave-like patterns, which pushes mucus up your throat. At the base of the bronchial tubes are tiny air sacs that hold the air you breathe in, called alveoli. Your right lung has three balloon-like sections, called lobes, which are full of spongy tissue. Your left lung has only two lobes, to make room for the heart. They sit in a special membrane called the pleura, that separates your lungs from the wall of your chest.

Your lungs are more like buckets than balloons.

Your lungs are not big bags of air. They’re more like buckets filled with blood that have air bubbles going through them. In fact, your lungs contain as much blood as the entire rest of your body, which is why your center of gravity is above your waist. They produce blood cells as well. Every time your heart beats, it sends an equal amount of blood to your lungs as it does everywhere else in your body. This amazing system respires (meaning, exchanges gas from air into the blood and lungs) without leaking.

Lungs are huge.

Lungs are one of the body’s biggest organs, but you might be surprised to learn that if you spread out the surface area of the alveoli, the sacs where oxygen and blood interface, you could cover an entire tennis court.

Without mucus, your lungs would dry up. 

You may not be a big fan of mucus when it’s clogging your chest or nose during a cold, but it’s a “highly underrated, powerful infection-fighting agent in your body with some pretty cool features,” Ray Casciari, chief medical officer at St. Joseph Hospital in Orange, California, told Mental Floss in 2017. “It’s actually cleaner than blood ... If you take bacteria and expose it to mucus, the mucus will stop the growth of the bacteria, whereas blood will actually support the growth of the bacteria.” (In fact, researchers in laboratories often deliberately use blood to grow bacteria.) Your mucus is such an important protective agent that you’d die without it. “If you didn’t have mucus in your lungs, you would dehydrate, losing so much water through evaporation that you would die within minutes,” Casciari said. On the other hand, too much mucus production is dangerous.

Whatever you inhale goes from your lungs to your brain. 

In under seven seconds, to be precise. Because of your lungs’ enormous surface area and “its intimate relationship with blood vessels that surround it,” said Scott Schroeder, a pediatric pulmonologist at Tufts Medical Center in Massachusetts, an inhalation of smoke or a vaporized medicine can reach the brain very quickly.

Coughing isn’t always bad for your lungs.

Even when you aren’t sick, a normal person coughs about 10 times per day, Schroeder told Mental Floss in 2017—whether due to a sticky piece of food, an allergen you accidentally inhale, or your own mucus generated by exercise.

Asthma isn’t just one disease affecting lung function.

Asthma, which causes wheezing, coughing, and shortness of breath, is actually a number of different illnesses under one name, Schroeder said. The good news is that deaths due to asthma are very uncommon, and have decreased significantly among most populations over the last 20 years, he reports (with one notable exception—African American men ages 18–24). But it doesn’t affect everyone equally. Women are much more likely to develop asthma as adults than men, especially if they are overweight. And people in urban areas are more likely to suffer from asthma than those in rural areas, likely due to increased particulate matter in the air from car exhaust and industrial pollutants.

Exercise can make asthma—and your lung function—better.

Asthma is actually improved by cardiovascular exercise. Schroeder said there are no sports that people with asthma cannot participate in, “except scuba diving, but I don’t consider that a sport.”

You can get lung cancer even if you’ve never smoked.

“You can spend your whole life in a very clean environment, never having smoked, and still get lung cancer,” Casciari said. Not all lung cancer is caused by cigarette smoking (though the majority is). Casciari cites occupational exposure, radiation exposure, and potential genetic risk factors, although researchers are still exploring the role genetics play. “Folks tend to think of their lungs very little, and when they do, they think, ‘I don’t smoke, so I’m ok,’ but that’s not completely true.”

Breakthroughs in lung cancer treatments have improved survival rates. 

For decades, toxic chemotherapy was the best medicine for treating lung cancer, but it comes with intense side effects. Several new breakthroughs have recently improved outcomes for patients, Casciari said. Thoracic CT scans, for example, improve survival by 20 percent by providing earlier diagnosis and treatments. New minimally invasive surgery techniques have made recovery from lung cancer surgery much easier, with people being discharged on the same day of surgery. Finally, immunotherapies that target specific cancer markers and harness the immune system itself to fight cancer cells have improved outcomes—and decreased side effects—for lung cancer patients.

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This story was first published in 2017 and has been updated for 2025.