6. As carbon dioxide diffuses into blood to alveolus, the partial pressure of CO, in blood lowers, thereby enhancing further uptake of oxygen.
7. oxyhaemoglobin remains unchanged until it reaches the tissues where it dissociates readily to release the oxygen bound to it.
8. Blood low in oxygen picks up oxygen as it diffuses from the alveoli where it has high concentration of oxygen into the blood capillaries where it has low concentration of oxygen.
9. Hydrogen ions are released from reduced haemoglobin and combine with bicarbonate ions to form carbonic acid 10. An enzyme, called carbonic anhydrase, helps convert the carbonic acid into carbon dioxide and water which diffuses into the alveoli.
11. The small amount of carbon dioxide found as