Asthma is a disease that affects the breathing passages of the lungs (bronchioles). Asthma is caused by chronic (ongoing, long-term) inflammation of these passages. This makes the breathing passages, or airways, of the person with asthma highly sensitive to various "triggers."
* When the inflammation is "triggered" by any number of external and internal factors, the passages swell and fill with mucus.
* Muscles within the breathing passages contract (bronchospasm), causing even further narrowing of the airways.
* This narrowing makes it difficult for air to be breathed out (exhaled) from the lungs.
* This resistance to exhaling leads to the typical symptoms of an asthma attack.
What Is Asthma?
Asthma (AZ-ma) is a chronic (long-term) lung disease that inflames and narrows the airways. Asthma causes recurring periods of wheezing (a whistling sound when you breathe), chest tightness, shortness of breath, and coughing. The coughing often occurs at night or early in the morning.
Asthma affects people of all ages, but it most often starts in childhood. In the United States, more than 22 million people are known to have asthma. Nearly 6 million of these people are children.