Question

Within the capillaries of the lungs, gases are exchanged by diffusion; oxygen diffuses from the _____ to the ____ and carbon dioxide diffuses from the _____ to the_____.

Answer 1

I guess that is:
Within the capillaries of the lungs, gases are exchanged by diffusion; O2 diffuses from the alveolus to the bloodstream and CO2 diffuses from the bloodstream to the alveolus.

Answer 2

1. alveoli to the bloodstream     2.bloodsteam to alveoli