The Airway · Lungs
The narrowest tubes — soft-walled, and able to squeeze shut.
Keep going and the tubes get smaller, and smaller, until they're thinner than a hair. These finest branches are the bronchioles — and unlike the tubes above them, they have no cartilage rings holding them open.
Instead their walls are wrapped in smooth muscle that can tighten or relax, narrowing or widening the passage. That's how the body steers air toward the best-supplied parts of the lung — and it's also exactly what tightens during an asthma attack.
Body Atlas is an educational product. It does not provide diagnosis, treatment, or personal medical advice. · Privacy