Overview

COPD slowly damages the lungs and affects how you breathe.

COPD's effect on breathing

COPD makes it hard to breathe because air doesn't flow easily in and out of your lungs.

Chronic bronchitis and emphysema are two lung problems that are types of COPD.

The oxygen and carbon dioxide exchange

The lungs are where the blood picks up oxygen to deliver throughout the body and where it disposes of carbon dioxide that is a by-product of the body processes. COPD affects this process.

Chronic bronchitis affects the oxygen and carbon dioxide exchange because the airway swelling and mucus can reduce the flow of oxygen-rich air into the lung and carbon dioxide out of the lung.

Emphysema affects the oxygen and carbon dioxide exchange because of the damage to the alveoli. These are the tiny air sacs that allow oxygen to get into the blood. Their destruction leads to the formation of large air pockets in the lung called bullae. These bullae do not exchange oxygen and carbon dioxide like normal lung tissue. Also, the bullae can become very large. Normal lung tissue next to the bullae can't expand as it should, reducing lung function.

The damage to the alveoli and airways makes it harder to exchange carbon dioxide and oxygen during each breath. Decreased levels of oxygen in the blood and increased levels of carbon dioxide cause the breathing muscles to contract harder and faster. The nerves in the muscles and lungs sense this increased activity and report it to the brain. As a result, you feel short of breath.