Interesting Facts About Lungs

September 7, 2010 | In: Medical facts

The lungs are a vital organ which enables the body to obtain oxygen from the air we breathe, and to eliminate carbon dioxide.

Breathing is accomplished with the chest wall muscles, and the diaphragm muscle, which separates the chest cavity from the abdomen. When the chest cavity expands, the lungs expand with it, drawing air down into the lungs. When the chest cavity relaxes, the lungs shrink, and waste carbon dioxide is expelled.

The lungs are not directly attached to the chest wall. Instead they are encased in a double layer membrane called the pleura. One of the pleural layers is firmly attached to the lungs with the other one firmly attached to the chest wall. There is always a small amount of fluid between the two pleural layers which allows them to freely slide over each other.

The lungs are divided into distinct lobes which are supplied by their own airways (bronchi) and their own arteries. On the right side, there are three main lobes called the upper, middle, and lower lobes. On the left, there are only two lobes called the upper and lower lobes. The fissures that separate the upper and lower lobes on both sides are called the major fissures. The right lung also has a minor fissure that separates the upper and middle lobes. The minor fissure is nearly horizontal, but the major fissures run at a steep angle. When a doctor listens to the breathing sounds on your back, he or she is listening to the lower lobes, even when the stethoscope is placed high up by the shoulder blades.

One of the disorders sometimes seen in the emergency room is a collapsed lung. Surprisingly, the natural tendency of the lungs is to collapse into a small ball near the center of the chest. They are held in their normal expanded state only by the attraction between the two layers of the pleura. If you have ever tried to separate two sheets of wet glass, then you know how this works. Occasionally, air gets between the two pleural layers, causing them to separate, and the lung collapses. This is called a pneumothorax, meaning air in the thorax (chest cavity). The air can either come from the outside because of a penetrating wound, or from the inside because a part of the lung developed a hole in it. Another problem that is sometimes seen is excess water between the two pleural layers. This is called a pleural effusion, a condition commonly referred to as water on the lung. There are many causes for a pleural effusion, some benign and some quite bad. A pleural effusion is typically treated by sticking a needle or a tube into the chest and draining out the fluid.