Your Child's Asthma: What Happens in the Lungs

When lungs are healthy, breathing is easy. With each breath, air goes down the windpipe (trachea) into the lungs. There, it flows through airways called bronchial tubes. The airways also make mucus to trap and help get rid of any particles that are breathed in. Muscles that wrap around the airways help with breathing. Air is breathed out through the same airways.

Child's head and torso showing upper and lower respiratory tracts.

How asthma affects the lungs

Here's how asthma affects the lungs:

With asthma, the airways are inflamed. The lining of the airways swells. Muscles around the airways may be tight. Air has to go through a narrower tube.
With asthma, the lungs are too sensitive to things that are breathed in. This causes inflammation. It also causes the lungs to make more mucus.
With asthma flare-ups, the airways can become even more swollen. The muscles around the airways tighten. More mucus forms. All of this narrows the airways even more. This causes breathing trouble—an asthma flare-up.

Normal bronchiole, a tightened bronchiole with asthma, and constricted bronchiole with excess mucus during asthma flareup.