which makes it easier for oxygen and CO 2 to pass between the alveoli and very small blood vessels (capillaries). Oxygen can ...

Oxygen passes through the walls of the alveoli and enters tiny blood vessels. The blood vessels carry oxygen around the body to where it’s needed. Carbon dioxide – a waste gas that the body ...

Blood-vessel blockages caused by abnormal clotting ... tract as well as the walls of the tiny grape-like air sacs called alveoli, through which gas exchange occurs to oxygenate the blood.