In comparison to the apex of the lung, the base of the lung has
High pulmonary arterial pressure O2
High pulmonary arterial pressure CO2
High ventilation / perfusion ratio
Same ventilation / perfusion ratio
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.