Question:medium
All of the following statements about bronchial circulation are true, except:
All of the following statements about bronchial circulation are true, except:
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Bronchial circulation feeds lung tissue; which job actually belongs to the pulmonary circulation?
Updated On: Jun 24, 2026
- It contributes about 2% of systemic circulation
- It contributes to gaseous exchange
- It causes venous admixture of blood
- It provides nutritive function to the lung
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The Correct Option is B
Solution and Explanation
Keep the two lung blood supplies separate in your mind. The pulmonary circulation is the functional supply that takes venous blood to the alveoli for oxygenation, while the bronchial circulation is the nutritive supply, a branch of the systemic circulation that feeds the airways and lung framework.
Grade each statement against that division. Saying the bronchial arteries make up around 2% of the systemic output is accurate. Saying they nourish the lung is exactly their defining function, so that is accurate too. The trickier statement is venous admixture: a portion of bronchial venous blood, which is deoxygenated, empties into the pulmonary veins and mixes with oxygenated blood returning to the left heart, slightly lowering its oxygen content; this is one reason a normal person has a small alveolar to arterial oxygen gradient, so that statement is also true.
The statement that fails is the one crediting the bronchial circulation with gaseous exchange. Oxygen uptake and carbon dioxide removal happen at the alveolar capillary membrane served by the pulmonary circulation, not by the bronchial vessels. An except question wants this false statement.
$\therefore$ the untrue statement is that the bronchial circulation contributes to gaseous exchange.
\[\boxed{\text{Contributes to gaseous exchange}}\]
Grade each statement against that division. Saying the bronchial arteries make up around 2% of the systemic output is accurate. Saying they nourish the lung is exactly their defining function, so that is accurate too. The trickier statement is venous admixture: a portion of bronchial venous blood, which is deoxygenated, empties into the pulmonary veins and mixes with oxygenated blood returning to the left heart, slightly lowering its oxygen content; this is one reason a normal person has a small alveolar to arterial oxygen gradient, so that statement is also true.
The statement that fails is the one crediting the bronchial circulation with gaseous exchange. Oxygen uptake and carbon dioxide removal happen at the alveolar capillary membrane served by the pulmonary circulation, not by the bronchial vessels. An except question wants this false statement.
$\therefore$ the untrue statement is that the bronchial circulation contributes to gaseous exchange.
\[\boxed{\text{Contributes to gaseous exchange}}\]
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