According to the National Institutes of Health ...
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 breath), chest tightness, shortness of breathe, 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.
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Overview
The airways are tubes that carry air into and out of your lungs. People who have asthma have inflamed airways. This makes the airways swollen and very sensitive. They tend to react strongly to certain substances that are breathed in.
When the airways react, the muscles around them tighten. This causes the airways to narrow, and less air flows to your lungs. The swelling also can worsen, making the airways even narrower. Cells in the airways may make more mucus than normal. Mucus is a sticky, thick liquid that can further narrow your airways.
This chain reaction can result in asthma symptoms. Symptoms can happen each time the airways are irritated.
Asthma
Figure A. Cross section of a normal airway.
Figure A shows a cross-section of a normal airway. Figure B shows a cross-section of an airway during asthma symptoms.
Figure B - Cross section of an asthmatic airway
Sometimes symptoms are mild and go away on their own or after minimal treatment with an asthma medicine. At other times, symptoms continue to get worse. When symptoms get more intense and/or additional symptoms appear, this is an asthma attack. Asthma attacks also are called flareups or exacerbations.
It's important to treat symptoms when you first notice them. This will help prevent the symptoms from worsening and causing a severe asthma attack. Severe asthma attacks may require emergency care, and they can cause death.
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