emphysema
Meaning of emphysema: The trouble is not only getting air in; damaged lungs have lost the springiness that used to push it back out.
Definition of emphysema
Emphysema is a lung disease in which the walls between the tiny air sacs break down, merging many small sacs into fewer large ones. That destroys surface area for gas exchange and strips the lung of the elastic recoil that normally drives air out, so air becomes trapped and breathlessness follows. It is one form of chronic obstructive pulmonary disease.
What goes wrong in the lung?
The alveoli are thin-walled sacs wrapped in capillaries, and elastic fibers woven through their walls do two jobs: they recoil to push air out, and they tether the small airways open so those airways do not collapse. Inflammatory cells release enzymes that digest elastin, and normally a protective protein restrains them. When that balance tips, walls dissolve. Surface area for oxygen and carbon dioxide to cross falls, and the small airways lose their tethers and shut during exhalation, so air is left behind. The chest becomes over-inflated, the diaphragm flattens, and the breathing muscles end up working at a mechanical disadvantage. Breathing out through pursed lips, which many people adopt without being taught, holds the airways open a little longer.
How does it differ from chronic bronchitis?
| Emphysema | Chronic bronchitis | |
|---|---|---|
| Defined by | Destruction of alveolar walls, a structural change | A productive cough on most days over long stretches of consecutive years |
| Core problem | Lost surface area and lost recoil | Excess mucus and an inflamed airway lining |
| Usual picture | Breathlessness on exertion, over-inflated chest | Persistent cough with sputum, frequent chest infections |
The distinction is real but rarely clean. Both sit under chronic obstructive pulmonary disease, and most people show features of each rather than one alone, which is why bronchitis and emphysema are so often discussed together.
What causes it?
Cigarette smoking accounts for the large majority. Long-term exposure to smoke from indoor cooking fires, occupational dusts and fumes, and heavy air pollution contribute in their own right. A distinct inherited cause is alpha-1 antitrypsin deficiency, a shortage of the very protein that restrains the wall-digesting enzymes; it produces emphysema at younger ages and characteristically damages the lower parts of the lungs, where smoking-related disease tends to strike the upper. Once alveolar walls are destroyed they do not regrow, so the structural loss is permanent, and attention turns to preventing further damage, easing symptoms and managing flare-ups.
Used in a sentence
Pulmonary function testing showed findings consistent with emphysema.
Good to know
Emphysema and chronic bronchitis frequently occur together under the broader heading of chronic obstructive pulmonary disease, so a person's presentation usually reflects a mixture of both processes rather than a single pure form.
Word origin
Where “emphysema” comes from
Formed from Greek emphysan, meaning to inflate or blow into, from em-, meaning in, and physan, meaning to blow, describing the abnormal inflation of the affected air sacs.