How do the Lungs Work?

Michael Anissimov
Michael Anissimov

Lungs provide our body with the oxygen it needs to generate energy in the form of adenosine triphosphate (ATP). ATP is the body’s energy currency, and it is necessary for all energy-consuming cellular processes. Over the course of a lifetime, a person may use their lungs to breathe over a billion times. Animals breathe in oxygen and exhale carbon dioxide, the opposite of plant respiration.

Respiration involves breathing in oxygen and breathing out carbon dioxide.
Respiration involves breathing in oxygen and breathing out carbon dioxide.

The lungs are the central component of the respiratory system, which is used for breathing. Fresh air comes in through the mouth, down the trachea (windpipe), into the lungs through cartilaginous pathways called bronchi and bronchioles, where it is absorbed by tiny air sacs called alveoli. Alveoli are about 0.05 mm in diameter, but swell to 0.1 mm during inhalation. By comparison, a typical cell is about 0.01 mm in size.

The lungs supply the body with oxygen, which it uses to generate energy.
The lungs supply the body with oxygen, which it uses to generate energy.

The entire process of inhalation is driven by the diaphragm, a large muscle below the lungs. When the diaphragm is at rest, the lungs open wide, drawing in oxygen. When the diaphragm tenses up, the lungs are compressed, ejecting carbon dioxide. This process repeats continuously, even while we are asleep.

Over the course of a lifetime, a person may use their lungs to breathe over a billion times.
Over the course of a lifetime, a person may use their lungs to breathe over a billion times.

The alveoli exist in a finely branching structure, starting from the large windpipe and continuing down to individual air sacs. Because of this branching structure, they have a very large combined surface area, about 750 – 1,000 square feet (70 – 90 square meters). This is similar in area to a football field, although the lungs themselves are only as large as a couple of steaks.

Lungs provide the body with oxygen, allowing it to generate the ATP necessary for energy.
Lungs provide the body with oxygen, allowing it to generate the ATP necessary for energy.

A network of capillaries — fine blood vessels — cover the alveoli. Oxygen from the alveoli diffuse into the bloodstream, which then travels to the heart, where it gets pumped around the body. Oxygenated blood has a bright red color, while deoxygenated blood has a bluish hue.

An accumulation of fluid in the alveoli may occur as a result of pneumonia.
An accumulation of fluid in the alveoli may occur as a result of pneumonia.

The lungs are not only for breathing. They also play a role in filtering the blood and shielding the heart, which is almost surrounded by them.

Wheezing sounds that emanate from the lungs may occur in patients who have asthma.
Wheezing sounds that emanate from the lungs may occur in patients who have asthma.
Michael Anissimov
Michael Anissimov

Michael is a longtime wiseGEEK contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

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Discussion Comments

anon86874

why are the walls of the blood vessels around the air sacs very thin?

anon64745

how do your alveoli work?

anon40853

how to improve the hemoglobin?

anon38350

How does one lung work if the other one has been damaged in some way?

anon36738

what is the treatment for lungs cell rejenuvation?

anon9862

How long does the lungs take to heal from the damage caused by smoking.

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