Asthma - Description
About ten million Americans have asthma, and the number seems to be increasing. Between 1982 and 1992, the rate rose by 42 percent. Asthma is also becoming a more serious disease. In the same 10-year period, the death rate from asthma in the United States increased by 35 percent. These changes have come about in spite of new and improved drugs for the treatment of asthma.
An asthma attack affects the bronchi (pronounced BRONG-ki) and bronchioles (pronounced BRONG-kee-olz) in the lungs. The bronchi and bronchioles are tiny tubes through which air passes in and out of the body. In people with asthma, certain materials, such as dust and pollen, can irritate these tubes. By contrast, people without asthma are unaffected by these materials.
As these tubes become irritated, they swell and give off mucus, a sticky liquid. The liquid fills air spaces in the bronchi and bronchioles. Both swelling and mucus narrow the tubes, making it more difficult for air to get in and out of the lungs. As a result, an asthmatic person has to make a much greater effort to breathe in air and to expel it.
Asthma usually begins in childhood or adolescence, however it may first appear during the adult years. While the symptoms may be similar for these two cases, certain aspects of asthma are different in children and adults.
Child-onset Asthma
Some children are thought to develop asthma for genetic reasons. Their bodies are especially sensitive to materials in the environment that have little or no effect on other people. These materials are known as allergens (pronounced AL-erjins) because they produce an allergic response.
- Allergen:
- A foreign substance which, when inhaled, causes the airways to narrow and produces the symptoms of asthma.
- Atopy:
- A condition in which people are more likely to develop allergic reactions, often because of the inflammation and airway narrowing typical of asthma.
- Spirometer:
- An instrument that shows how much air a patient is able to exhale and hold in his or her lungs as a test to see how serious a person's asthma is and how well he or she is responding to treatment.
When children with this condition are exposed to dust mites, fungi, and other allergens, their bodies produce chemicals known as antibodies. The function of these antibodies is to fight off the invasion of materials from the environment. However, the release of antibodies also inflames the bronchi and bronchioles. The more often an asthmatic child is exposed to allergens, the more serious the response becomes. This condition, known as atopy (pronounced A-tuh-pee), is thought to occur in anywhere from 30 to 50 percent of the general population.
Adult-onset Asthma
Some individuals do not exhibit the symptoms of asthma until their adult years. In some cases, the cause of the disease may be the same as they are for children. In other cases, asthma is thought to be a result of exposure to wood dust, metals, certain forms of plastic, or other materials that get into the air in the workplace or at home.
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