Chronic obstructive pulmonary disease, or COPD, is a disease that is actually characterized by two lung diseases. Chronic bronchitis and emphysema are two similar lung diseases that cause obstruction in the airways, making breathing more difficult. If either or both are diagnosed, then the individual has COPD.
With chronic bronchitis, there is inflammation in the lining of the bronchial tubes. The inflammation reduces air flow and causes the production of excessive phlegm. Over time, the chronic inflammation leads to scarring and thickening of the tissue, along with a permanent cough.