Download Factors affecting the O2 dissioation curve

Factors affecting the O2 dissioation curve
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‫العاشرة‬
A 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+ concentration
2- Partial pressure of CO2
3- Temperature
Factors that sift the curve to left :
1. H+ concentration
2. Temperature
B- CO2 Carriage
Forms 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-NHCOOH
b) 89% as NaHCO3 In plasma or KhCO3 In red cells.
c) 2% with plasma proteins.
Importance 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 metabolism
Carriage of Tidal CO2 :
a) 5% In physical solution
b) 10% Buffered by plasma protein
c)85% Buffered by Hb .
Role 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
c) Reaction Between H2CO3and Hb acid.
Carbonic anhydrase:
It is an enzyme present inside RBC, but not in
the plasma (this prevents it from being lost in
urine).
It accelerates the reaction.
C. A
CO2 + H2O 

H2CO3
Exchange of gases between blood and tissue