3 02 



RESPIRATION 



The blood consists of a fluid plasma with a mass of corpuscles floating in 

 it. The gas analysis of the blood shows that it contains oxygen, carbon 

 dioxide, nitrogen, and traces of other inert gases. The blood gases are 

 measured by the method of extracting them, measuring the volume and 

 computing the volume to standard temperature and pressure. 



Numerous analyses of the blood from the arteries and veins of normal 

 men have recently been obtained by Stadie, Harrop, and others, made 

 possible by the development of the micro-analytical methods and appara- 

 tus introduced by Van Slyke, Fig. 237. Arterial blood obtained by 

 puncture from the radial artery with a slender hypodermic needle and 

 syringe have yielded on analysis the following average volumes per cent, 

 of oxygen. 



Arterial and Venous Oxygen, Total Oxygen Capacity, and Arterial and Venous Oxygen Unsaturation 

 in Five normal Individuals (Stadie) 



The amount of oxygen per unit quantity of blood varies with the con- 

 centration of hemoglobin. In blood from the radial artery the sample is 

 under normal respiratory conditions about 93 to 97 per cent saturated, 

 See Harrop, Table I. 



The amount of carbon dioxide in the total blood averages about 40 

 volumes per cent, in arterial blood and 46 to 58 volumes per cent, in venous 

 blood. Venous blood may contain as much as 65 volumes per cent, of car- 

 bon dioxide. The carbon dioxide-carrying bases are largely in the plasma 

 and increase or decrease with variations of acid or alkali production, 

 thereby maintaining equilibrium. The amount of nitrogen in solution in 

 the blood follows closely its ratio of physical absorption by fluids. Saturated 

 arterial blood contains 1.52 volumes per cent, of nitrogen. Venous blood 

 contains somewhat less, about 1.36 volumes per cent. (Van Slyke and 

 Stadie). 



