Which of the following is higher at the apex of the lung than at the base when a person is standing?

Ans. A. V/Q ratioa. The alveoli at the apex of the lung are larger than those at the base so their compliance is less. Because the compliance is reduced, less inspired gas goes to the apex than to the base.b. Also, because the apex is above the heart, less blood flows through the apex than through the base.c. However, the reduction in airflow is less than the reduction in blood flow, so that the V/Q ratio at the top of the lung is greater than it is at the bottom.d. The increased V/Q ratio at the apex makes PA CO2 lower and PA O2 higher at the apex than they are at the base.