l62 



BIOLOGICAL CHEMISTRY 



HEMOGLOBIN 



The amount of gas dissolved in a liquid is proportional 

 to the partial pressure of the gas above the liquid. The 

 presence of respiratory pigments upsets this relation as 

 we no longer deal with a solution of gas in the same molecular 



CO 



50 



40 



30 



20 



FIG. 37- 



Ordinates = percentage saturation of ha?mog!obin with oxygen. 



Abscissae = tension of oxygen in mm. of mercury. 



Curve I = rectangular hyperbola, xy 800. 



Curve II = Bohr's dissociation curve of haemoglobin. 



points determined from dialysed solution. 



D points determined from undialysed solution. 



(From "Respiratory Function of the Blood," J. Barcroft, by permission of the Editor of the 

 "Journal of Physiology.") 



condition as in the vapour space above the liquid. We 

 have a small amount of gas in solution and a larger 

 amount associated in some way with the respiratory pigment. 

 The result is that at low pressures of oxygen relatively more 

 is contained in the solution than at high pressures. This 

 result is due to oxygen uniting with the haemoglobin at low 



