Introduction to Chronic Obstructive Pulmonary Disease

People must breath in order to live. The process of breathing ("respiration", in medical terminology) is critical because it is the sole mechanism through which vital gasses such as oxygen and carbon dioxide can move between the air and the blood. When someone breaths in, oxygen is removed from the air and dissolved into the blood where it is used as fuel by the body's cells. When someone breaths out, cellular waste products like carbon dioxide are removed from the blood and exhaled back out into the air. This complex transfer of gasses takes place in the lungs and involves a number of structures associated with the lungs that help move gasses between the lungs and the air: the bronchi (airways or passages within the lungs), and the alveoli (tiny air sacs composed of special membranes found at the end of the bronchi at which point the transfer of gases between the blood and the air occurs).

Chronic Obstructive Pulmonary Disease (COPD for short) occurs when permanent blockages form within the pulmonary system (the term "pulmonary" refers to the lungs and respiratory system) that interfere with the transfer of vital gasses. To be diagnosed with COPD means that some portion of one's bronchi or alveoli have become permanently obstructed, reducing the volume of air that can be handled by the lungs. As this process progresses, the overall efficiency of the gas exchange process is reduced.

There are two underlying disorders that can cause COPD: Emphysema and chronic Bronchitis.

Bronchitis is literally an inflammation of the bronchi. The walls of the bronchi inside the lungs become inflamed, and this inflammation decreases the bronchi's diameter so that less air is able to flow through than normal. The inflammation process promotes excessive production of mucous. Bronchial mucous, which serves to keep the airways clean and free of bacteria, is produced under normal conditions. However, the excessive mucous produced in bronchitis is thicker and more difficult to cough up than normal, and acts to clog the airways and inhibit lung capacity.

Emphysema also reduces the efficiency of the gas exchange process, only in a different manner. Emphysema affects the alveoli, specifically their sensitive membranes through which the gas exchange process occurs. Emphysema causes alveolar membranes to lose elasticity, become brittle, and then actually rip and tear. Broken alveolar membranes cannot be regenerated by the body. Each time alveolar membranes burst, more surface area within the lung necessary for gas transfer is permanently lost. As this process progresses, it becomes very difficult for patients to exhale because their weakened airways threaten collapse the harder they try to breathe out. The heart tries to compensate for the loss of oxygen available in the bloodstream by pumping harder and faster; a process associated with other serious complications including heart failure.

Asthma is another respiratory disease that may be associated with COPD but which is not itself classified as COPD. People who have asthma have highly sensitive bronchi that are more reactive to environmental irritants like smoke, dust and pollen than are the bronchi of people who do not have asthma. During an asthma attack, asthma patients' bronchi swell and narrow in a manner similar to what occurs in bronchitis, restricting the volume of gasses that can be transferred between the blood and the air. At this time, the exact relationship between asthma and COPD is unclear. However, there is some evidence to support the "Dutch Hypothesis" that both asthma and COPD have common genetic origins and may represent different expressions of a similar disease process. The jury is still out on whether the Dutch Hypothesis is accurate or not, but numerous researchers believe that it is at least partially true that asthmatic people may have a heightened genetic vulnerability for COPD.