Transportation of oxygen : It ctake splace in the following way :
1. In solution form : Oxygen is less dissolved in plasma–about 3% gets transported in solution form.
2. As oxyhaemoglobin : Oxygen combines with haemoglobin to form oxyhaemoglobin. One molecule of haemoglobin combines with four molecules of oxygen to form oxyhaemoglobin. In the alveoli there is high pO2, low pCO2, lesser H+ concentration and lower temperature, these factors favour the formation of oxyhaemoglobin. Whereas in the tissues, where low pO2, high pCO2, high H+ concentration and higher temperature exist, . Since the Haemoglobin molecules take oxygen from respiratory organs and give oxygen to the cells of the body.
Fig. Diagram of the exchange of gases
About 97% oxygen is carried in combination with haemoglobin.