CHAPTER XVII 

 RESPIRATION AND ACIDOSIS 



Respiration is the process by which oxygen is introduced into and 

 carbon dioxide removed from the body. By external respiration is 

 meant the gaseous exchange in the lungs between the blood in the 

 pulmonary capillaries and the air in the alveoli. Internal respiration 

 is the similar exchange taking place in the systemic capillaries between 

 the blood and tissue elements. The actual oxidation processes in 

 the tissue cells are considered under metabolism (Chapter XXVIII). 



The table shows the alterations which inspired air undergoes in 

 passing through the lungs. Results are expressed in volume per cent. 1 



It will be seen that all of the oxygen taken in is not excreted as CO 2 , 

 some of it going to form water and other oxidation products eliminated 

 for the most part by the kidneys. 



The next table shows the changes which commonly take place in the 

 gaseous composition of the blood in passing through the systemic 

 capillaries (results also expressed in volume per cent). 



Practically all of the oxygen of the blood is carried in chemical 

 combination with the hemoglobin. 



Practically all of the COz is carried by the blood as carbonic acid 

 (H^COa) and bicarbonates (BHCOs) of sodium and potassium. These 

 always exist in such relative proportions as to maintain the approxi- 

 mately neutral reaction of the blood. 2 



The alkali which combines with the CC>2 and makes possible this 



1 Benedict, F. G., "Carnegie Publication" 166, 1912; Lee, F. S., Jour. Ind. and Eng. 

 Chem.y 6, 247, 1914. 



2 Henderson L. J.: Jour. Biol. Chem, 46,. 411, 1921. 



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