What term describes the matching of ventilation to perfusion in the lungs?

• A. Diffusion capacity
• B. Ventilation-perfusion matching
• C. Oxygen saturation
• D. Alveolar ventilation

Answer: (B)

Ventilation-perfusion matching is about how well the air reaching the alveoli (ventilation) aligns with the blood flowing past them in the pulmonary capillaries (perfusion). This coordination determines how efficiently oxygen is picked up and CO2 is released. When ventilation and perfusion are well matched, gas exchange is optimized. If ventilation is high but perfusion is low, some alveoli don’t contribute much to gas exchange (dead space). If perfusion is high but ventilation is low, blood passes through with insufficient oxygenation (a shunt-like effect). The term that describes this coordination is ventilation-perfusion matching.

Diffusion capacity is about how easily gases cross the alveolar-capillary barrier, not the matching of air and blood. Oxygen saturation is a measurement of how much oxygen the hemoglobin is carrying, not the process that ensures efficient exchange. Alveolar ventilation refers to the amount of air reaching the alveoli, not the relationship between air and blood flow.