Role of red blood cells in the transport of oxygen:
(i) Red blood cells are known as erythrocytes. They carry oxygen in the form of an unstable, easily dissociable chemical combination with haemoglobin.
(ii) O2 diffuse into RBCs and combines usually with haemoglobin to form oxyhaemoglobin.
(iii) In tissues oxyhaemoglobin dissociates into oxygen and deoxyhemoglobin at low partial pressure.
(iv) The blood carries its full load to O2 until it enters the capillaries in tissues to the lungs.
Role of red blood cells in the transport of CO2 :
(i) Carbon dioxide is carried by RBCs. About 30% of CO2 is carried by RBC's from tissues to the lungs.
(ii) CO2 on entering the red blood cell loosely combines with the amino group of reduced Hb and forms carbaminohemoglobin.