COPD: Anatomy of the lungs and changes due to COPD

How do your lungs work?

Air travels down your windpipe (trachea) and into your lungs through two large tubes. Inside your lungs, these tubes divide many times — like the branches of a tree — into many smaller tubes that end in clusters of tiny air sacs.

The air sacs have very thin walls full of tiny blood vessels. The oxygen in the air you inhale passes into these blood vessels and enters your bloodstream. At the same time, carbon dioxide (CO₂) — a gas that is a waste product of metabolism — is exhaled.

Your lungs rely on the natural elasticity of the airways to force air out of your body. COPD causes them to lose their elasticity and over-expand, which leaves some air trapped in your lungs when you exhale.

Main causes of obstructions

• Emphysema weakens your airways and causes them to collapse when you exhale, so less air can get out of your lungs.
• Chronic bronchitis: your airways become inflamed and narrowed, leading to more mucus production. You develop a chronic cough trying to clear your airways.
• Asthma causes inflammation in the airways, leading to difficulties in breathing, wheezing, and sometimes episodes where air struggles to move in and out of the lungs