Asthma is a respiratory system disorder in which the passages that allow air to pass into and out of the lungs periodically narrows, causing coughing, wheezing, and shortness of breath. This narrowing is typically temporary and reversible, but in severe attacks, asthma may result in death. Asthma most commonly refers to bronchial asthma, an inflammation of the airways, but the term is also used to refer to cardiac asthma, which develops when fluid builds up in the lungs as a complication of hear failure. This report focuses on bronchial asthma.
More than 14 million Americans suffer from asthma, with more than 4 million cases occurring in children. In the United States, asthma causes more than 5,000 deaths each year. Among Americans, asthma has increased more than 60 percent between 1982 and 1994, especially among children. Deaths from asthma increased more than 55 percent from 1979 to 1992. Scientists think it has increased from more exposure to second-hand cigarette smoke, growing populations, and poor ventilation.
Every cell in the body requires oxygen to function, and the lungs make that oxygen available. With every breath we take, air travels to the lungs through a series of tubes and airways. After passing through the mouth and throat, air moves through the larynx, and then through the trachea. The trachea divides into two branches, that connect directly to the lungs. Air continues through the bronchi, which divide into smaller and smaller air passages in the lungs, called bronchioles. The bronchioles end in clusters of tiny air sacs, called alveoli, which are surrounded by tiny, thin-walled blood vessels.
Deep in the lungs, oxygen diffuses through the walls and into the blood in the capillary, and gaseous waste products in the blood diffuse through the capillary walls and into the alveoli. But if something...