1. Respiratory Function of the Blood A- Oxygen Carriage Blood normally contains about 15 g of haemoglobin per 100 C.C. Since one gm hemoglobin carries a maximum of 1.34 C.C of O2 arterial blood could when saturated to its full capacity, contain 20 C.C.O2 per 100 C.C. blood as it leaves the lungs is about 97% saturated with O2 so that O2 content at this saturation is 19.5 C.C. -A-At the normal arterial oxygen tension of 100m.m Hg about 0.3 C.C of O2 is dissolved in every 100 C.C blood This physically dissolved O2 can't supply the tissue with their requirements even under complete rest. المحاضرة التاسعة

2. Thus O2 is carried in a loose chemical combination whit haemoglobin (Hb) : Hb + O2 HbO2 Steps of Haemoglobin formation : 1. Acetic acid – Ketoglutaric acid. Kreb's cycle 2. 2( ketoglutaric acid ) glycine pyrrole 4. 4Protoporphyrin fe ++ Heam 3. 4( pyrrole ) protoperphyrin 5. Haem + globine Haemoglbine molecule

3. Reaction of Hemoglobin and Oxygen : Hb4 + O2 Hb4O2 O2 Hb4O4 O2 Hb4 O6 O2 Hb4 O8 Oxygen Dissociation curve Hb structure

4. Oxygen Dissociation curve : This is the reaction curve of O2 with Hb at dIfferent pressures of dissolved O2 in the blood The curve is obtained by placing several samples of blood each in a separate closed vessel know as " tonometer ". The respective samples are exposed to know O2 tension 0,10,20,40 up to 100 m.m Hg. Definitions: 1-Oxygen content - Is the volume of O2 in chemical combination with Hb in 100 C.C blood. 2-oxygen capacity Is the maximum amount of O2 Which can combine with Hb in 100 C.C blood

5. 3.Qxygen percentage = 4.Coefficient of oxygen utilization :