RESPIRATION 



419 



Naturally the absorption of oxygen and the discharge of carbon dioxid 

 and the changes of composition which are incident to nutrition will be most 

 marked in those tissues characterized by the greatest degree of physiologic 

 activity. Muscle-tissue exhibits these changes to a greater degree than 

 bone. Tissues with intermediate degrees of activity should exhibit corre- 

 sponding degrees of respiratory change. Experiment confirms this view. 

 Thus, 100 grams each of muscle, spleen, and broken bone from a recently 

 living animal exposed to the air for twenty-four hours absorbed respectively 

 50.8 c.c., 27.3 c.c., and 17.2 c.c. of oxygen, while each discharged during the 

 same period 56.8 c.c., 15.4 c.c., and 8.1 c.c. of carbon dioxid respectively. 



Atmospheric Air. 



Ox-iss mm.flg ', or 20.85 per cent , 



COz - 0.3 m. H&, or 0. 04 joer cen t, 



of an atmosphere. 



Ox-Tension 



38 mm If?, 



S per cent. 



C0 x -7ension- 



4J.8mm H#, 



&5 per cent. 



J%^ 







Alveolus 



Arterial 

 Blood. 



Venous 

 *\Blood. 



OzTension O. 

 C&fenston i 



6 to 9 per cent. 



Ox-Tension. 



2O6m,nt. ffff, 



J4percent 



COz -Tension 



38 m, nt fig, 



Jper cent 



Tissues. 



FIG. I97.-DIAGRAM SHOWING THE RELATIVE TENSION OF OXYGEN AND CARBON DlOX 

 THE LUNGS, IN THE BLOOD, AND IN THE TISSUES. 



In another series of experiments by a different observer 100 grams of muscle 



absorbed in three hours 23 c.c. of oxygen, and 100 grams of 1 



oxygen. Both tissues discharged carbon dioxid in amounts proper 



the oxygen absorbed. The same respiratory changes may be more satis- 



factorily" demonstrated by passing bl ood, througl: .the ^ M^ted 



organs and the tissues of recently living animals. The analys 



before and after perfusion shows a loss of oxygen and a gam i 



nsion of the Gases in the Tissues. -As the presence of Jree oxygen 

 cannot be demonstrated, its tension there must be regarded as m/. 



