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Explain why the following happen :

(a) Far more oxygen is released from oxyhaemoglobin in a more active tissue than in a less active one.

(b) Oxygenation of blood promotes the release of carbondioxide from blood in the lungs.

 

Answer

(a) Far more oxygen is released from oxyhaemoglobin in a more active tissue than in a less active one.- This is because in more active tissue PO2 is lower and PCO2 is higher. The PO2 is much lower and the PCO2 is much higher in an active tissue than less active. Both these favour dissociation of oxyhaemoglobin to deoxyhaemoglobin and molecular oxygen.

(b) Oxygenation of blood promotes the release of carbondioxide from blood in the lungs -  because oxyhaemoglobin is a stronger acid than deoxyhaemoglobin. So, it denotes Hion which combine into water and CO2 by carbonic anhydrase. Bicarbonates release CO2. Affinity of haemoglobin for oxygen is enhanced due to the release of CO2 from blood in lungs which causes fall in PCO2 of blood.