alleryStart learning →What do the pulmonary arterioles do when alveolar oxygen pressure is high?
AThey dilate and blood flow increases
BThey constrict and blood flow falls
CThey dilate and blood flow falls
DThey constrict and blood flow rises
Answer & Solution
Correct answer: A. They dilate and blood flow increases
1. Perfusion is matched to ventilation by adjusting vessel calibre.
2. A greater partial pressure of oxygen in the alveoli makes the pulmonary arterioles dilate.
3. Dilation increases blood flow to that well-ventilated region, so the first option is correct.
4. The third and fourth options pair a vessel response with the wrong flow change, which is impossible in a single vessel.
_Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 22 "The Respiratory System", section 22.4 Gas Exchange_
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