Respiratory bronchioles
Summary
Transitional conducting airways marking the beginning of the respiratory zone, distinguished from terminal bronchioles by scattered alveoli budding from their walls. Have simple cuboidal epithelium with Clara cells.
Detail
Respiratory bronchioles represent the transition between conducting and gas-exchanging airways. The defining feature is alveoli budding from their walls, allowing partial gas exchange. They have lost cartilage and submucosal glands. Typically 0.5-1mm diameter. Pathologically, they are the primary site of respiratory bronchiolitis (smoking-related) and centrilobular emphysema. The anatomy is clinically important for understanding disease distribution patterns.
Sources
- First Aid for the USMLE Step 1
- Robbins Basic Pathology
- Histology textbooks
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