Dr. Stephen Teach, a pediatrician in Emergency Medicine at the Children's National Medical Center in Washington DC, discusses the function of our lungs in relation to asthma. Asthma is in actuality a disease of the tubes of the lungs that deliver oxygen to the blood. When the tubes become obstructed and narrow due to various reasons, asthma begins to develop.

"What is Asthma?"



Stephen:



So asthma is a disease of the lungs, specifically it's a disease of the tubes of the lungs. The tubes move the air in and out, allowing the lungs to deliver oxygen to the blood. What happens in asthma is the tubes, which are usually wide open and air can pass very easily through them, become obstructed. They become obstructed for two reasons: One is a swelling or an inflammation of the walls, and they swell for a lot of reasons. Due to allergies, due to viruses, due to irritants like tobacco smoke; that swelling and mucus production has the effect of narrowing the diameter of the tubes, and if you will making it more difficult for the air to pass in and out. The other thing that happens in the tubes which causes them to narrow, is what we call bronchial constriction. What that is, is that the smooth muscle which is in the walls of the tubes contracts and narrows the diameter of the tubes. Again, in that effect of which is that it's difficult for the air to pass in and out.