We all know that the lungs are among our most important organs. They take life-sustaining oxygen into the body and get rid of gases like carbon dioxide from the body. Even though the lungs are so vital, many people do not know exactly how they work. Learning the individual parts of the lungs and their roles in the respiratory system allow patients to understand exactly how their breathing works. This may help to explain how certain disorders in the respiratory (breathing) system affect the body and how they can be treated. So, how do our lungs work?
The lungs, or rather, the respiratory system, can be “broken down” into five main parts: the upper airways, the trachea, the bronchi and bronchioles, and the alveoli. The lungs themselves only contain the bronchi (large air tubes), bronchioles (small air tubes) and alveoli (air sacs), but the pharynx (back of the throat) and trachea (windpipe) are important to lung function as well. By following the path of air as it moves into and out of the body, we can examine each part in detail.
The Upper Airways
The upper airways include the nasal cavity and mouth, the pharynx and the larynx. The reason these parts of the respiratory tract are all grouped under one name is that the purpose they all serve is to simply direct air into the lungs. As we breathe in, the upper airway warms the air and adds moisture to it so that it is more comfortable for our lungs. Many people are familiar with the parts of the upper respiratory system, which is the site of most common colds. The pharynx and larynx also have more common names, the throat and voice box, as well.
Once air moves down through the upper airways, it reaches the trachea, or “windpipe.” The trachea is basically a tube with an upside-down Y shape. It can be thought of as the first part of the lungs reached by air when inhaling. The trachea serves to direct air into the two lungs. The trachea has a protective coating of special cells that helps defend against inhaled dust and particles. This airway is also surrounded by muscles and rings of cartilage. These help the trachea to maintain its shape so that air can always pass to and from the lungs with ease.
The Bronchi and Bronchioles
After the air passes through trachea, it moves into arms of the upside-down “Y,” the large airways called the left bronchus and the right bronchus. A series of tubes, known as the bronchi (large tubes) and bronchioles (small tubes) are referred to as the bronchial tree because they resemble the branches of a tree that get smaller and smaller as they get closer to the leaves. These structures, similar to the trachea, carry air further into the lung and attach finally at the alveoli, which are like the leaves.
The alveoli, also known as air sacs, are responsible for the most important work done in the lung: the transfer of gases. The alveoli are very, very small sacs of air attached to the ends of the smallest airways, the bronchioles. The air sac is made of a very thin membrane (tissue). When we breathe air in, oxygen moves across that membrane and into the small blood vessels that go through the lung. Carbon dioxide and other gases from the blood cross the membrane and are then exhaled through the same structures that oxygen-rich air came in. Then, the process is repeated over and over again.
Understanding how our lungs work is not a very complicated issue when we take this problem and break it down into parts. This new knowledge can help patients understand how some of the more complex disorders and diseases of the lung affect the body.