Emphysema overview
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Emphysema overview On the Web |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Emphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath. In people with emphysema, the tissues necessary to support the physical shape and function of the lungs are destroyed. It is included in a group of diseases called chronic obstructive pulmonary disease or COPD (pulmonary refers to the lungs). Emphysema is called an obstructive lung disease because the destruction of lung tissue around smaller sacs, called alveoli, makes these air sacs unable to hold their functional shape upon exhalation. Emphysema is most often caused by tobacco smoking and long-term exposure to air pollution.
The term emphysema means "swelling" and derives from the Greek ἐμφυσᾶν emphysan meaning "inflate" - itself composed of ἐν en, meaning "in", and φυσᾶν physan, meaning "breath, blast".[1]
Pathophysiology
Emphysema is caused by loss of elasticity of the lung tissue, from destruction of structures supporting the alveoli, and destruction of capillaries feeding the alveoli. The result is that the small airways collapse during exhalation, leading to an obstructive form of lung disease (airflow is impeded and air is generally "trapped" in the lungs in obstructive lung diseases). When toxins such as smoke are breathed into the lungs, the particles are trapped and cause a localized inflammatory response. Chemicals released during the inflammatory response (e.g., elastase) can break down the walls of alveoli (alveolar septum). This leads to fewer but larger alveoli, with a decreased surface area and a decreased ability to absorb oxygen and exude carbon dioxide by diffusion. The activity of another molecule called alpha 1-antitrypsin normally neutralizes the destructive action of one of these damaging molecules.