asthma

Science Dictionary
asthma   (āz'mə)  Pronunciation Key 
A common inflammatory disease of the lungs characterized by episodic airway obstruction caused by extensive narrowing of the bronchi and bronchioles. The narrowing is caused by spasm of smooth muscle, edema of the mucosa, and the presence of mucus in the airway resulting from an immunologic reaction that can be induced by allergies, irritants, infection, stress, and other factors in a genetically predisposed individual. Common symptoms of asthma include wheezing, coughing, and shortness of breath.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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