Chronic Obstructive Pulmonary Disease is an umbrella term for numerous lung diseases that affect breathing. It refers to lung diseases that are chronic, progressive and mostly irreversible. The most common lung diseases included under this term are emphysema and chronic bronchitis. Chronic Obstructive Pulmonary Disease damages the airways that carry air to the lungs.
The airway walls become narrowed and swollen, therefore obstructing the airflow in and out of the lungs. Some forms of Chronic Obstructive Pulmonary Disease can scar the lungs and lead to increased airway resistance. Other forms can induce the excessive secretion of phlegm that the lungs are not able to clear.