Why does regional hypoxia develop when the ventilation-perfusion ratio decreases drastically in specific lung alveoli during pulmonary embolism?

💡 Explanation

A low ventilation-perfusion ratio indicates that blood is flowing past alveoli that are not adequately ventilated; because gas exchange relies on matching airflow to blood flow, a mismatch impairs oxygen uptake. Therefore, hypoxia develops because oxygen cannot diffuse into the blood, rather than carbon dioxide excretion increasing or vasodilation compensating for poor ventilation.

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