CGI image of Alveoli lungs.  Tiny air sacs at the end of the bronchioles. The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out. Oxygen breathed in from the air passes through the alveoli and into the blood.  It then travels to the tissues throughout the body. Carbon dioxide travels in the blood from the body's tissues and passes through the alveoli to be breathed out. Polymime is a UK based animation company offering royalty free medical stock images and medical stock videos.  Other services including 3D rending, medical animation interactive 3D, vfx and more.