How the Lungs Work

The lungs are the central component of the respiratory system. They take in oxygen and expel carbon dioxide, gas that is removed from the body each time you exhale. The respiratory system supplies the body’s cells with oxygen and expels the cells’ wasted carbon dioxide gas. But the lungs perform other valuable functions in addition to breathing and exchanging gases. They also act as a secondary filter to reduce harmful materials in your body.

The Respiratory System

When you breathe, inhaled oxygen enters the windpipe or trachea. It then travels through the trachea and into both the left and right bronchi, and then again into decreasingly smaller bronchioles that branch off on both sides of the body in “V” shapes, like tree limbs. The smaller bronchioles continue dividing, each into more than 100,000 smaller tubes that end in even smaller tiny air sacs and clusters called alveoli. That is where oxygen is exchanged for carbon dioxide.

Each alveolus is surrounded by large numbers of tiny blood vessels or capillaries. It’s in those tiny alveoli where the gas exchange happens: oxygen is supplied to the body’s cells through the capillaries and carbon dioxide gas is removed. The carbon dioxide then makes the journey in reverse where it’s eventually exhaled through the nose and mouth.

An Important Defense System 

Another vital function of the lungs is to trap harmful particles such as bacteria, viruses, and pollutants from reaching other parts of the body. To do this, the bronchioles are aided by cilia, tiny hair-like extensions that help move material back up through the lungs that is trapped in the mucus secreted by the cells.   

The mucus produced in the lungs assists in trapping and expelling certain harmful bacteria and viruses.  Together with the help of the cilia, bacteria and other foreign particles are either sneezed or coughed out of the body. Or, if they’re swallowed, they enter the stomach and are eventually released as waste.

Producing mucus is normal. Everybody coughs and expresses sputum. However, if a person’s lungs are damaged because of COPD, mucus can build up in the lungs, making it harder to breathe. Cilia in the lungs of people with COPD is damaged or completely destroyed. This makes it increasingly difficult for COPD patients to cough up excess mucus.

Over time, people with COPD lose much of their lung function. The airways become less elastic and the walls between them become increasingly inflamed or are completely destroyed. Because the cilia are also damaged, increasing fluid build up further compromises airways and makes it harder to breathe. Bacteria and viruses thus get trapped in the lungs and flourish, developing into infections.

Allergic reactions can also increase the amount of mucus in the lungs. This is often the case in people who suffer from seasonal allergies and asthma. Sometimes too much mucus build-up can compromise a person’s ability to breathe and result in a flare-up or exacerbation. A short-acting bronchodilator can usually quickly reduce inflammation in the lungs and open up the airways enough to promote breathing.