Emphysema is a lung condition that's almost always *part* of chronic obstructive pulmonary disease (COPD). COPD is the umbrella term that also includes chronic bronchitis, another common condition that people
can have at the same time as emphysema.
Having COPD means that the person's lungs have developed permanent changes that affect the body's ability to exhale properly. These changes tend to worsen over time.
In emphysema, the lung damage is deep in the lungs, where it affects the alveoli, tiny air sacs at the end of the larger airways (bronchi). These are the parts of the lungs that allow oxygen to move from the air to your blood and that move the waste gas carbon dioxide from the blood to the air. This exchange helps the entire body function properly and is fundamental to breathing.
In someone who has developed emphysema, the air sacs have become stretched out and floppy. Most often, this is due to chronic irritation from toxins in cigarette smoke. The floppy air sacs don't exchange oxygen and carbon dioxide as well as they should, and they also tend to trap air. Instead of many little air sacs, there are fewer, bigger, less efficient ones. People with emphysema get short of breath easily and can't exhale quickly.