Function of the alveoli

• Blood passing next to the alveoli has just returned from the lungs from the rest of the body
• The blood that passes next to the alveoli from the lungs contains a high concentration of carbon dioxide and a low concentration of oxygen
• oxygen difuses out of the aleveoli high concentration into the blood low concentration
• Carbon dioxide diffuses into the alveoli low concentration which is from the blood high concentration to be breathed out