Upright position ventilation and perfusion of lungs
In Upright position ventilation in more at base of the lungs than apex. This is because at the start of the inspiration apex is more distended compared to the base. Because of the stiffness of the lung, the increase in lung volume per unit increase in pressure is smaller when the lung is initially more expanded, and ventilation is consequently greater at the base
Blood flow is more at the base compared to apex
So the ventilation-perfusion ratio less at the base compared apex.