This is how the lungs work

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Last Medical Review: April 1, 2020
Medically Reviewed by Dr. Elisabeth Vincent Hamelin
How the Lungs Work (April 1, 2020)

We breathe in oxygen and exhale carbon dioxide. The oxygen and carbon dioxide get to and from the lungs through the nose, throat and trachea. In the lungs the blood takes up the oxygen and passes it on to the various parts of the body.

The airways carry air to the lungs

Your body needs oxygen to live. The lungs absorb oxygen from the air as you breathe in. The lungs then release the gas carbon dioxide as you exhale. The air passes through what is called the airways.

The airways can be divided into six different parts:

  • the nose
  • sinuses
  • throat
  • larynx
  • trachea
  • air pipes.

The airways heat the inhaled air and make it moist so that the lungs are not damaged.

The nose filters and heats the air

Inside the nose is a cavity called the nasal cavity. The nasal cavity is divided into two halves. The two nostrils lead into each half of the nasal cavity. In each nasal cavity there are three so-called nasal clams. Backward, the nasal cavity leads into the pharynx.

The nose consists of both cartilage and bone. Cartilage is a tissue that is softer than bone tissue. Cartilage is both durable and flexible.

The inside of the nose is covered with mucous membranes and cilia

Some of the important tasks of the nose are to heat, moisturize and clean the air you breathe. The inside of the nose is covered with mucous membranes and cilia. The mucous membrane moistens the inhalation air. Under the mucosa is a network of small blood vessels. The blood vessels make the air in the nose warmer.

Inside the nostrils are hairs. They catch dirt from the air you breathe in. Nevertheless, debris and dust enter the nose. This gets stuck in the mucus that comes from the mucous membrane. The flicker hairs then bring down the debris and dust to the throat.

The sinuses make the skull easier

The sinuses are located near the nose and are connected to the nasal cavity through narrow passageways. The sinuses are cavities in the bones of the skull. On the inside, the sinuses are covered with the same type of mucosa that is found in the nasal cavity.

You have sinuses in the following places in both halves of the face:

  • in the jaw bone
  • in the forehead
  • in the silver bone
  • in the wedge leg.

The sinuses make the skull lighter and they also affect how the voice sounds.

The pharynx

The pharynx is covered with mucosa

The top of the throat is covered with the same mucous membrane that is found in the nasal cavity and sinuses. The lower part of the throat has a stronger mucous membrane to withstand all food and drink that passes.

In the upper part of the throat there are passages leading to the ear trumpets in the middle ear. At the back of the throat hangs a flap of skin called the tummy tuck.

In the throat are the tonsils

The tonsils are two glands that sit on either side of the throat at the same height as the back of the tongue. Neck tonsils can also be called tonsils. The name neck tonsils comes from the glands of an adult person having the shape and size of an almond.

The tonsils consist of so-called lymphatic tissue. Lymphatic tissue is part of the body’s immune system. The tonsils protect the respiratory tract and the gastrointestinal tract from infections.

The tonsils are larger in children and shrink during teens. In adults they tend to be much smaller than in children.

The larynx

The larynx consists of different parts of cartilage. The cartilage parts together form the entrance to the trachea. You can feel the larynx on the neck. The task of the larynx is to keep the trachea open so that we can breathe and to keep the trachea closed so that we can swallow.

The choke lid prevents the food from falling into the wrong throat

A tab called the larynx partially covers the entrance to the larynx. The larynx folds over the larynx as you swallow. It prevents the food from getting into the wrong throat, that is to come down the trachea instead of the esophagus.
On the inside, the larynx is covered with the same type of mucosa that is found in the nose, sinuses and the top of the throat.

The vocal cords create sound

Inside the larynx are the two vocal cords stretched. They are elastic and tighten and relax as the cartilage moves. This opens and closes the gap between the vocal cords. When the gap is open, air can pass through the trachea.

The sounds that make up the voice occur when air is pressed through the larynx and sets the vocal cords in oscillation. The air also starts to turn and the sound is amplified by the cavities in the chest, throat, mouth, nose and sinuses. The words are then formed with the help of the cheeks, teeth, lips and tongue.


From the larynx, the trachea continues down through the chest. The trachea is right in front of the esophagus.

The trachea is made up of rings of cartilage

The trachea is made up of cartilage rings stacked on top of one another. They sit together with the help of muscles and so-called connective tissue. On the inside, the trachea is covered with the same type of mucosa that is found in the rest of the airways.

The trachea is about 10 inches long. It then divides itself into two large trachea that go into each lung.

The bronchial tubes

The trachea goes from the trachea into the lungs. Inside the lungs, the trachea continues to divide into smaller trachea. The larger trachea contains cartilage to keep the tubes stretched. The smallest have very thin walls without cartilage. At the far end of the lung tissue, the thin trachea ends in the bladder. The lung blisters are also called alveoli.


The lungs are in the chest. Between the lungs are the trachea and the esophagus. The lungs absorb oxygen to the body from the air we breathe. The blood then transports oxygen to the body’s cells and tissues.

The body’s cells thus receive oxygen from the blood. They also release carbon dioxide into the blood. The blood then transports the carbon dioxide to the lungs. The carbon dioxide then leaves the body as we exhale.

The body needs oxygen to function

Oxygen is essential for the cells and the body to function. The brain can only be oxygen free for a few minutes before it is damaged. Carbon dioxide, on the other hand, is harmful and must be removed from the cells. The cells stop working if the carbon dioxide stops too long.

The lungs are divided into lobes

The right lung is divided into three so-called lobes and the left lung into two lobes. The lobes are then divided into several smaller parts. Each part has its own trachea and blood vessels. Each lung is surrounded by a so-called lung sac with double walls of connective tissue.

The lungs are made up of air bladders

The lungs are made up of a special kind of tissue with lots of air bubbles that contain air. This makes the lungs have about the same texture as a sponge. In each lung there are approximately 400 million lung blisters. The walls of the lung bladders are very thin for oxygen and carbon dioxide to pass easily. The lung blisters are surrounded by a network of small blood vessels, so-called capillary networks.


Usually we breathe through the nose. The ribs are lifted and the middle leg lowered as we breathe. The pressure inside the lung sacs decreases and the lungs expand. The air is sucked into the lungs and eventually reaches the lungs.

The air is squeezed out of your lungs as you exhale. At each breath, about half a liter of air flows into the lungs and just as much out of them. When you rest, you breathe about twelve times every minute.

With exertion, you breathe more often than at rest, and you breathe more air in each breath. You also breathe through your mouth as you exert yourself.

Breathing is controlled from the brain

The inhalation and exhalation are controlled by signals coming from the respiratory center. The respiratory center is located in the part of the brain stem called the extended marrow. Various reflexes also regulate breathing. You breathe more as the content of carbon dioxide in the blood increases. This is because the body needs to get rid of the carbon dioxide. In this way, breathing is automatically adjusted to the needs of the body. You can also affect breathing with the will, and it happens from the so-called cerebral cortex.

The exchange of oxygen and carbon dioxide

In the lungs there are so-called lung blisters. They are located at the far end of the thin trachea. It is in the lung vesicles that the exchange occurs between oxygen and carbon dioxide. Around the pulmonary vesicles are thin blood vessels called capillaries. Oxygen and carbon dioxide can pass through the thin walls of the capillaries and also in and out through the thin walls of the lung bladders.

Oxygen is transported to the body’s tissues

The air you breathe contains oxygen that your body needs. When inhaled, oxygen in the air enters the body through the airways, to the lungs and even out to the pulmonary vesicles. The oxygen then passes out from the pulmonary vesicles and into the capillaries. Then the oxygen is transported into the blood vessels called the pulmonary veins to the heart and further out into the body. In the blood, oxygen is mostly bound to hemoglobin.

Carbon dioxide is transported from the body

The capillaries found around the pulmonary vesicles also contain carbon dioxide. The carbon dioxide is transported to the lungs from the various tissues of the body. The blood vessels that carry the carbon dioxide to the lungs are called the pulmonary arteries. Inside the lungs, carbon dioxide passes out through the thin walls of the capillaries and into the pulmonary vesicles. The air you exhale contains carbon dioxide.

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