Transport of Oxygen in Blood and tissue fluids DR AMNA TAHIR DIFFUSION OF OXYGEN FROM THE ALVEOLI TO THE PULMONARY CAPILLARY BLOOD PO 2 Of gaseous oxygen in the alveoli = 104 mm Hg PO 2 Of venous blood entering the pulmonary capillary at its arterial end = 40mm Hg Initial pressure difference= = 64mm Hg PO 2 Of the blood rises to that of alveolar air by the time the blood has moved a third of the distance through the capillary Uptake of oxygen by the pulmonary blood during exercise Greater safety factor Up take of oxygen by the pulmonary blood TRANSPORT OF OXYGEN IN THE ARTERIAL BLOOD 98 % OF the blood that enters the left atrium with PO 2 = 104 mmHg 2% OF the blood has passed the bronchial circulation ( SHUNTED BLOOD) with PO 2 =40 mmHg Venous admixture of blood PO 2 of the blood pumped by aorta = 95 mmHg DIFFUSION OF OXYGEN FROM THE PERIPHERAL CAPILLARIES INTO THE TISSUE FLUID PO 2 at the arterial end= 95 mmHg PO 2 in the interstitial fluid that surround the tissue cells= 40mmHg Tissue PO 2 is determined by 2 factors 1.Rate of oxygen transport to tissues in the blood 2.The rate at which the oxygen is used by the tissues DIFFUSION OF OXYGEN FROM THE PERIPHERAL CAPILLARIES TO THE TISSUE CELLS Intracellular PO 2 ranges 5-40 mmHg Average 23 mmHg 1-3 mmHg is required Larger safety factor ROLE OF HEMOGLOBIN IN OXYGEN TRANSPORT 97% is carried in chemical combination with Hb 3% is transported in dissolved state Reversible combination of oxygen with Hb Oxygen-Hemoglobin Dissociation curve