Chronic obstructive pulmonary disease, or COPD, affects around 12 million people in the United States and is the fourth leading cause of death, the National Heart, Lung and Blood Institute states. Smoking is the leading cause of COPD. COPD results from destruction of air sacs in the lungs along with a loss of elasticity in the lung. The walls of the lungs thicken and produce extra mucus, blocking the airways. Continuing to smoke with COPD ensures that the disease will worsen, The Merck Manual Online Medical Library stresses.
Alveolar Destruction
Emphysema, which is part of COPD, results from destruction of alveolar walls and enlargement of the alveoli themselves from chemicals released by the lungs in response to cigarette smoke. Alveoli, air sacs that contain many small blood vessels called capillaries, aid in oxygen and carbon dioxide exchange in the lungs. When alveoli enlarge, the number of capillaries decreases, resulting in decreased air exchange. The enlarged alveoli become overinflated and floppy, so air gets trapped and doesn't move in and out of them as well as it should. When people continue to smoke with COPD, destruction of alveoli continues and air exchange decreases further. Oxygen therapy may be required to supply adequate levels to the lungs. Even with oxygen, some people may have difficulty carrying out normal activities of daily living.
Bronchial Inflammation
Chronic bronchitis, another component of COPD, occurs as a result of inflammation in the bronchial tubes, which lead from the throat to the lungs. Irritants in cigarette smoke cause inflammation. Inflammation narrows the bronchial tubes, leaving less room for air to travel in and out of the lungs and also causes an increase in mucus production, further narrowing and blocking the airways. The smooth muscles in bronchioles, the small airway tubes in the lungs, spasm in response to the inflammation. When people continue to smoke with chronic bronchitis, inflammation worsens, leading to worsening chronic cough and shortness of breath. Stopping smoking when disease is still mild or moderate reduces inflammation and mucus production and slows the progression of shortness of breath, according to Merck.
Cilia Damage
The lining of the lungs contains a number of small hairs called cilia that move continuously back and forth to clear the lungs of irritating substances. Chemical irritants and pollutants slow cilia action and over time stop it altogether, HelpwithSmoking.com states. This allows chemicals to build up in the lungs and increase the risk of developing infection in the lungs. Once COPD develops, this process can't be fully reversed, HelpwithSmoking.com warns.
