Gas exchange occurs by the process of square Gas exchange occurs in saclike structures called square square diffuses from the alveolar sacs into the blood in the capillaries. square diffuses from the blood in the capillaries into the alveolar sacs.

Gas exchange occurs by the process of diffusion.<br /><br />Gas exchange occurs in saclike structures called alveoli.<br /><br />Oxygen diffuses from the alveolar sacs into the blood in the capillaries.<br /><br />Carbon dioxide diffuses from the blood in the capillaries into the alveolar sacs.