How the Lungs Work
The lungs are a remarkable organ. Through the lungs we get our main source of energy – oxygen. At the same time, the waste product, carbon dioxide, is breathed out. The lungs also have defenses against the dirt and other things that are in the air we breathe.
In order to take a breath in we normally use our diaphragm. This is a large muscle that sits at the bottom of our lungs. When we take a breath in the diaphragm contracts and moves down. It pulls the lungs with it which opens them up and pulls air into them. When we breathe out the diaphragm relaxes and moves up. This pushes the air out of our lungs.
When the air comes into the lungs it moves through the nose and/or mouth, through the throat and into the windpipe or trachea. The trachea divides in two and sends a tube to each of our lungs; one goes to the right side and one to the left. These tubes continue to divide and get smaller as they move out into the lungs. At the end of the smallest air tubes are tiny air sacs. These look a little bit like tiny balloons and connect to the air tubes like clusters of grapes. The air sacs or alveoli are surrounded by blood vessels. The oxygen rich air inside of the air sac is transferred into the blood stream and carbon dioxide replaces it in the air sacs. When we breathe out the air has very little oxygen in it and lots of carbon dioxide.
One of the defenses against the impurities in the air we breathe is our mucous. This is a sticky substance that lines the larger air tubes. Particles stick to it as the air moves through. This keeps the unwanted particles in the air from getting into the air sacs. Underneath the mucous layer are small hair-like projections called cilia. It is the cilia’s job to move the layer of mucous along and out of the lungs. The lungs are making mucous all of the time, and the cilia are moving it out of our lungs. Often we are not aware of this; we actually swallow the mucous without realizing it. When we have a cold or infection the lungs make more mucous and that is when we cough more out of our lungs.
