COPD generally encompasses emphysema and/or chronic bronchitis. These are two different diseases that are most often (but not always) caused by smoking. The term "obstructive" in the name, is based on characteristic changes in pulmonary function tests (breathing tests) in which there is obstruction to airflow - that is, your ability to empty your lungs. Many individuals who have smoked will have some combination of both of these two conditions, which are described below.
Emphysema is a condition characterized by enlarged airspaces that are inefficient at gas exchange and that also result in obstruction of small airways due to loss of the outward tension on the airway walls, normally provided by the surrounding airspaces. The net result is lungs that are chronically over inflated, symptoms of shortness of breath with exercise, and low oxygen levels in severe cases.
This is a condition in which there is an increase in the normal amount of mucus produced in the airways; this excess mucus can block the airways, obstructing airflow. This usually manifests as a cough productive of sputum (phlegm) on most days ("smoker's cough"); sometimes this is most apparent upon awakening in the morning. Increased mucus production is a result of irritation of mucus glands by cigarette smoke or other irritants, such as pollution or smoke.
Treatments for COPD consist of behavioral therapies (smoking cessation), exercise programs (rehabilitation), medicines (inhaled bronchodilators; occasionally inhaled steroids), and prevention of exacerbations (flu vaccines, pneumovax, smoking cessation.) A small proportion of patients can be treated with surgical procedures, including lung volume reduction surgery or even transplantation.