Respiratory bronchiole
Respiratory zone · Gen 17-19 First alveoli Acinus begins
Each terminal bronchiole divides into respiratory bronchioles (generations 17 to 19), the first airways with alveoli budding from their walls and therefore the start of the respiratory zone and of the acinus. The epithelium is simple cuboidal with club cells and the last few cilia; gas exchange begins here.
Traced from the start
- Trachea
- Right main bronchus
- Right upper lobe bronchus
- Right middle lobe bronchus
- Right lower lobe bronchus
- Left main bronchus
- Left upper lobe bronchus
- Left lower lobe bronchus
- Right upper lobe segmental bronchiRight middle lobe segmental bronchiRight lower lobe segmental bronchiLeft upper lobe upper division bronchiLingular bronchus and segmentsLeft lower lobe segmental bronchi
- Bronchioles and terminal bronchiole
- Respiratory bronchiole
Detail
- Generations
- 17 to 19; the transitional zone between conducting and respiratory airways
- Acinus
- Everything distal to one terminal bronchiole: two or three generations of respiratory bronchiole, the alveolar ducts and sacs, about 3 to 5 mm across
- Epithelium
- Simple cuboidal with club cells, interrupted by alveolar openings lined by pneumocytes; cilia stop here
- Blood supply
- Bronchial arteries reach about this level; beyond it the walls are nourished by the pulmonary circulation
When it goes wrong
Cigarette smoking
Centriacinar (centrilobular) emphysema: destruction starts in the respiratory bronchioles and is worst in the upper lobes, sparing the distal alveoli early on
Smoking-related respiratory bronchiolitis
Pigmented macrophages fill the respiratory bronchioles; centrilobular nodules on CT and a mild interstitial lung disease that improves with smoking cessation
Coal dust inhalation
Coal macules collect around the respiratory bronchioles in a centriacinar pattern, with focal emphysema
Practise this structure
No question in the bank is tagged to Respiratory bronchiole yet. Questions appear here automatically once one is — the question bank is free to browse in the meantime.