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About 12 million Americans have asthma, which means someone you know probably has the disease. Even though it is so common, doctors don't know what causes asthma. They do know it isn't contagious. Asthma usually strikes during childhood. Half the children who get asthma outgrow it by adolescence. The other half spend their lives using medications and avoiding things that trigger attacks. An attack happens when something irritates an asthma sufferer's respiratory system, triggering a series of events that make it difficult for the sophisticated structures within the lungs to get oxygen into the bloodstream. An asthma attack begins by striking the bronchi, the two large tubes that connect the windpipe to the lungs, and the bronchioles, the many little tubes that carry air from the bronchi deep into the lungs. In normal lungs, air from the bronchi moves into tiny air sacs called alveoli. Oxygen moves from these sacs into the bloodstream through tiny blood vessels called capillaries. At the same time, carbon dioxide is removed from the blood and exhaled from the body. An asthma attack causes the muscles surrounding the lungs' airways to tighten. The airways can also become inflamed and swollen, making breathing much more difficult. Finally, the lungs increase production of mucus that clogs the airways even more. Asthma victims often make wheezing sounds and cough as they struggle to breathe and clear out the excess mucus. For someone with asthma, breathing out, or exhaling, is as hard as breathing in. Scientists don't think asthma is inherited, but they suspect genes that make it easier for allergies and other environmental irritations to develop into asthma are passed on from parents to children. If neither parent has asthma, you have a 10 percent chance of developing it. If one parent has asthma, your odds increase to 25 percent. If they both have it, you have a 50 percent chance of developing the disease. Many things bring on asthma attacks and these triggers vary from person to person. Cold winter air, cleaning solvents, dust, spicy food, aspirin, and cigarette smoke can all be triggers. Exercise and strong emotions also can cause attacks. So can viral and bacterial infections. With so many triggers, how can people with asthma live normal, active lives? Most do by inhaling medications that dilate, or open, constricted airways and stop inflammation. They also learn what their specific triggers are and try to avoid them. A cure isn't on the horizon, but people with asthma can control the disease and turn it into an inconvenience, not a barrier to a full life.


In this activity you will create a simple model of the respiratory system. Not only will you measure the effect of narrowed airway channels, you will experience it as well. Materials
  • notebook, pen, and ruler
  • construction paper, scissors, and tape
  • balloons-large and round, that blow up to about 25 cm (10") in diameter
  • plastic drinking straws .6 cm (1/4") in diameter, cut to 15 cm (6") lengths
  • rubber bands 2.5-5 cm (1"-2") in length
  • stopwatch or watch with sweep second hand
  • honey dispensed from a plastic squeeze bottle with funneled spout
1. Divide into teams of four. Each team should use an inch-wide strip of construction paper and tape to make a ring 25 cm (10") in diameter. Each team member will need three balloons. Two of the balloons will be modified by inserting a 15 cm (6") length of drinking straw about 2.5 cm (1") into the opening and securing it with a small rubber band. (About eight twists will make the connection airtight and still not crimp the plastic straw.) 2. Each team member takes a turn at blowing up a plain balloon. Inflate the balloon until it just fills the paper ring, which is held by another team member. The third team member measures the time needed to inflate the balloon to the nearest second, while the fourth team member records the data. When inflation is complete, pinch the balloon shut. Reset the watch, then release the air from the balloon. Record the time it takes for the balloon to deflate completely. 3. When each team member has performed the trial with a plain balloon, repeat the entire process with one of the modified balloons. Record the times needed to inflate the balloon to 25 cm and to deflate it completely. 4. When this trial is finished, each team member takes the remaining modified balloon and squirts about 2 teaspoons of honey into the balloon through the straw. Gently squeeze the balloon so that the entire length of the straw is filled with honey. Inflate the balloon to 25 cm as before. Record the inflation and deflation times. 5. Calculate the average inflation and deflation times for the three trials performed by your team. Compare the results with those from the other teams. Questions 1. In our model, the three balloons represent different conditions in the human respiratory system. What are they? 2. How did narrowing the passageway and adding a thick, sticky substance affect your ability to blow up the balloon? 3. How do medicines treat an asthma attack?


    Rooklin, A. (1995) Living with asthma.
    New York: Plume.
    Sander, N. (1994) A parent's guide to asthma: How you can help your child control asthma at home, school, and play. New York: Plume.
    American Lung Association
    1740 Broadway
    New York, NY 10019
    (212) 315-8700
    Free educational material
    about asthma.
    Asthma Allergy Foundation of America
    1125 15th Street NW
    Washington, DC 20005
    (800) 727-8462
    Mothers of Asthmatics
    10875 Main Street, # 210
    Fairfax, VA 22030
    (703) 385-4403
    National Asthma Education and Prevention Program Information Center
    4733 Bethesda Avenue
    Bethesda, MD 20814

    Web sites
    Asthma support group
    National Jewish Center for Immunology and Respiratory Medicine