sentence: Carbon dioxide passes from the blood into the alveoli.
sentences_before: The alveoli are moist to allow oxygen to move from the lung through the alevoli into blood vessels and red blood cells.
sentences_after: The oxygen-filled blood goes back to the heart and the carbon dioxide in the alveoli is pushed out of the lungs and into the air we breathe out.
concept_name: carbon dioxide
headings: Lung
categories: Anatomy of the respiratory system