Select the phrase that best describes po2 at the arterial ends of the pulmonary capillaries. the po2 is higher at first in the capillaries than in the alveoli, and then it is lower in the alveoli than in the capillaries. the po2 is lower at first in the capillaries than in the alveoli, and then it is higher in the alveoli than in the capillaries. the po2 is lower in the capillaries than in the alveoli. the po2 is higher in the capillaries than in the alveoli. the po2 is equal in the capillaries and in the alveoli.