True statement regarding pulmonary ventilation is -: (A) PaO2 is maximum at the apex, (B) V/Q is maximum at the base, (C) Ventilation per unit lung volume is maximum at the apex, (D) Blood circulation is minimum at the base
Answer is A. Apical alveoli have low ventilation and perfusion per unit volume of the lung, whereas the basal alveoli have high ventilation and perfusion.
Ventilation-perfusion ratio and the PaO2 is maximum at the apex. PCO2 is maximum at the base.