The bronchial circulation !
- Concept
- For completeness
The lung has two blood supplies: the pulmonary one to oxygenate blood, and the bronchial one that feeds the airways with blood from the aorta.
Updated 2026-11-01
Also called: Bronchial arteries, Physiological shunt
See it in 3D: Azygos veins · Main bronchi · Pulmonary veins
What it is
The bronchial arteries arise from the thoracic aorta (or intercostal arteries) and carry oxygenated blood at systemic pressure to the bronchi, supporting tissue, visceral pleura and lymph nodes. They receive only about 1–2 % of cardiac output. Part of their venous blood returns through bronchial veins to the azygos system, but part drains into the pulmonary veins, creating a small physiological shunt.
Key facts
- With chronic inflammation (bronchiectasis, cavitary tuberculosis) bronchial arteries enlarge and become tortuous; at systemic pressure they bleed heavily.
- Lung tumors draw their blood supply mainly from bronchial arteries.
- In lung transplantation the bronchial arteries are usually not reconnected; the bronchial anastomosis relies on pulmonary flow.
- The bronchial circulation warms and humidifies air in the airways and sustains the mucosa.
Clinical notes
- Massive hemoptysis from bronchiectasis or old tuberculosis: bronchial artery embolization is an option because the lung does not depend on these arteries for gas exchange.
- Pulmonary embolism: infarction is more likely when bronchial flow is also compromised (heart failure, prior lung disease).
- Tuberculosis, still common in Colombia, leaves cavities and bronchiectasis with hypertrophied bronchial arteries.
Test yourself
Think of the answer, then tap the question to see it.
Why is arterial PO₂ slightly lower than alveolar PO₂ even in a healthy lung?
Some bronchial venous blood (and Thebesian venous blood from the heart) drains straight to the left side without passing alveoli: a small physiological shunt.
Why can hemoptysis from bronchiectasis be massive?
The bleeding comes from hypertrophied bronchial arteries working at systemic pressure, not from low-pressure pulmonary vessels.
Why does pulmonary embolism rarely cause lung infarction?
Lung tissue also receives bronchial blood and O₂ directly from alveolar air; infarction needs those sources to fail too.
See it in 3D
The structures of Durgical's 3D anatomy where it happens.
Related topics
- The pulmonary circulation and hypoxic vasoconstriction
- Ventilation–perfusion matching and West zones
- The alveolar gas equation and the A–a gradient
- Airway defenses, cough and mucociliary clearance
Related conditions
Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given.
Sources: 22.2 The Lungs (OpenStax (Rice University), 2022); Anatomy, Thorax, Bronchial (StatPearls (NCBI Bookshelf), 2026); Bronchiectasis (StatPearls (NCBI Bookshelf), 2026); Hall JE. Guyton and Hall Textbook of Medical Physiology, 13th ed. (ch. 39). Reference book used to check facts; its text and figures are not reproduced (Elsevier, 2016).
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Representative model, for educational purposes only.