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What is COPD?

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Updated February 01, 2014

What is COPD? © A.D.A.M.

Chronic Obstructive Pulmonary Disease (COPD) is a disease in which the airways and tiny air sacs (alveoli) inside the lungs are partially obstructed or destroyed. The result is labored breathing. There are varying degrees of this illness, and different names for them, but it all comes back to damaged airways and air sacs. This disease occurs when a person breathes in lung irritants of some kind: smoke, chemicals, pollution, dust. It makes sense then, that the most common cause of COPD is smoking.

The inside of our lungs look like upside down trees, with the trunks at the top, tapering down to tiny branches at the bottom. At the ends of the branches, there are many thousands of tiny round air sacs. In healthy people, the passageways to the sacs are clear and open. The sacs are bouncy and strong. When we take a breath, the sacs fill up like little balloons, and deflate when we breathe out.

In lungs with COPD, the airways are partially blocked, and the air sacs are floppy and out of shape. When a person breathes in, the sacs don't fill as well, and the result is shortness of breath. One or all of these things may be happening inside of the lungs:

  • The airways and the air sacs have lost their springiness, like an old rubber band might do.
  • The walls between many of the sacs have been destroyed.
  • The walls of the airways become thick from inflammation
  • Cells in the airways are making more mucus[sputum] and the airways are getting clogged due to that.

Chronics bronchitis happens when the airways are inflamed and thickened. More of the cells in the airways are making mucus, so the result is a habitual cough and difficult breathing.

Emphysema is what occurs as more and more of the walls between air sacs get destroyed. Instead of having lots of little sacs, the sacs break up and what is left are fewer larger sacs. These bigger sacs have less surface area for the exchange of oxygen and carbon dioxide than the tiny ones. Poor exchange of oxygen and carbon dioxide causes shortness of breath.

Often, people with COPD have both chronic bronchitis and emphysema. Most are smokers or former smokers. This is a disease that develops slowly from repeated exposure to lung irritants. Most people don't begin to show symptoms until they're 40 years of age or older. While the damage is permanent, by quitting, a person can improve how they feel, and stop further damage from happening.

Next:  COPD Symptoms and Treatments

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