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Childhood Asthma

Tell Me About Asthma

This web page will tell you about lung anatomy and what asthma is, as well as what the common symptoms are.

Anatomy of the Lungs A little anatomy

The lungs consist of airways (also known as bronchial tubes, or bronchi), and air sacs (also known as alveoli). The purpose of the airways is to allow fresh air to travel into the air sacs, and to allow spent air to travel out of the lungs. In the alveoli, fresh oxygen is moved into the blood, and waste gas (or carbon dioxide) is taken out of the blood, so it can be exhaled into the atmosphere. The bronchial tubes have tiny bands of muscle, which encircle them.

Why are bronchial tubes surrounded by bands of muscle?

Imagine a situation where you had to breathe noxious air — for example, suppose you were in a burning house. The muscles around your bronchial tubes would tighten up, to try to keep smoke out of your lungs. The inner lining of your bronchial tubes would start to produce mucous — to trap any soot and ash that got down there. And you'd start to cough — to help move the soot, ash, and smoke out of your lungs. These are normal reactions — that we'd all have. The lungs of an asthmatic produce these reactions when they're not supposed to — in response to things that shouldn't cause problems — for example, after exposure to pollens, animal dander, or dust.

Picture of Muscle Bands Surrounding the Bronchial Tubes
Why do the lungs of people with asthma react this way?

The inner lining of the bronchial tubes contains special cells, called inflammatory cells, which release chemicals after exposure to irritants. These chemicals cause the bronchial muscle constriction, mucous secretion, swelling of the bronchial tube inner lining, and coughing. Some of these chemicals also tell the body to send more inflammatory cells into the area. The lining of the bronchial tubes of asthmatics contain more of these special cells. In addition, in asthmatics, the inflammatory cells release their chemicals after exposure to things the person is allergic to — for example, after exposure to dogs, or cats, or ragweed.

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