Presentation on theme: "Factors affecting the O2 dissioation curve"— Presentation transcript:
1Factors affecting the O2 dissioation curve المحاضرة العاشرةFactors affecting the O2 dissioation curveA number of factors can influence the affinity of Hb to oxygen . (tissue activity tempertue can shift the curve either to right or to left- shift to right : means Hb give O2 to tissues ever under high PO2.- shift to left : means Hb give less O2 to the tissue under low PO2.Factors affecting the shift of the curve to right :1- H+ concentration2- Partial pressure of CO23- Temperature
2Factors that sift the curve to left : H+ concentrationTemperatureB- CO2 CarriageForms of CO2 in Arterial Blood :In physical solutions 5%In chemical combination 98% in the following forms.a) 4% in direct chemical combination with Hb forming carbamino compound Hb-CO2-NHCOOHb) 89% as NaHCO3 In plasma or KhCO3 In red cells.c) 2% with plasma proteins.
3Importance of arterial CO2 : It Represent a store for strong base ( NahCO3 ) available for neuttra li station offends formed in the body by normal or abnormal processor metabolismCarriage of Tidal CO2 :a) 5% In physical solutionb) 10% Buffered by plasma proteinc)85% Buffered by Hb .
4Role of Haemoglobin in CO2 Exchange : Mechanism: a)At The Ph of blood HBO2 is stronger acid than Hb and thus combines with more potassium In tissues when Hb o2 Is changed to Hb some potassium m Ions are released and combine whit some of CO2 added to form KHCO3 This mechanism accounts for buffering of about 40% of tidal CO2 .b) Reduced Hb has a power to from carbamino -compounds nearly double that of HbO2 when reduced Hb Is oxygenated in the lungs it gives of half its content of CO2 In this carbamino compound CO2 is very mobile and easily changed This mechanism is responsible for buffering of about 20% of tidal Co2
5Carbonic anhydrase: c) Reaction Between H2CO3and Hb acid. It is an enzyme present inside RBC, but not in the plasma (this prevents it from being lost in urine).It accelerates the reaction.CO2 + H2OH2CO3