What Is Emphysema - What Is Copd: Respiratory Health

Content provided by the Faculty of the Harvard Medical School

What is emphysema?

In contrast to chronic bronchitis, which affects the passages that carry air to and from the lungs, emphysema affects the lung tissue itself. The disease destroys the walls between many of the tiny air sacs, known as alveoli, leaving the lungs unable to absorb oxygen and expel carbon dioxide normally. Imagine that your lungs are like a large house with many small rooms. Emphysema functions like a demolition crew that breaks down the walls between the rooms, leaving less total wall space (surface area) inside. Less surface area means your lungs deliver less oxygen to your bloodstream.

At the same time, the lung tissue also loses its resilience, which prevents it from stretching and recoiling properly. When the lungs lack resilience, they cannot expel air as forcefully, and it becomes trapped in the air sacs.

The main symptom of emphysema is breathlessness. At first, you have difficulty catching your breath when you exert yourself, but when the disease is advanced, you may feel breathless after taking just a few steps or even while sitting or lying down. You may also lose weight. The work of breathing burns calories, causing weight loss when breathing consumes a greater portion of the calories you take in. Another reason for weight loss is that extreme difficulty breathing can make it hard to eat.

Last updated:	May 23, 2007