Reversible Reaction Pathways

• Respiring cells releases carbon dioxide • CO2 diffuses into blood plasma • CO2 diffuses into ethroyctes • CO2 an water react to form carbonic acid • reaction catalysed by carbon anhydrase • carbon acid dissociates to form hydrogen and hydrogen carbonate ions • hydrogen carbonate ions diffuses into the blood plasma • chloride ions diffuse into ethrocytes to replace hydrogen ions - chloride shift • the dissociate hydrogen ions reacts with haemoglobinic acid and the oxygen is releases

• Oxygen diffuses from the alvelous into erythrocytes down a concentration gradient • oxygen reacts with haemoglobinic acid to release hydrogen ions and produce oxyhaemoglobin • chloride ions diffuse back hydrogen carbonate ions and hydrogen reacts to form carbonic acid is broken down into water and carbon dioxide • catalysed by anhydrase • carbin dioxide diffuses out of the blood plasma into the alvelous • carbon dioxide is breathed out.