652 GENERAL THERAPEUTIC MEASURES 



This heat formation is of extreme importance in stimu- 

 lating and sustaining nervous action. 



Among proteids in food are the nucleoalbumins, so-called 

 because they exist in both animal and vegetable cells. The 

 nucleoalbumins are extremely valuable, since they contain 

 iron and phosphorus. They are absorbed by special epithe- 

 lial cells of the intestinal walls and are converted in part 

 into animal nucleoalbumin, as found in the various cells of 

 the body and iu milk and eggs ; while a portion is oxidized 

 and split up in the liver, forming haemoglobin, the iron com- 

 pound of the blood, and lecithin, the phosphorus compound 

 essential to nervous tissue. It is now held that iron can 

 only be supplied the blood as a nucleoalbumin and that 

 when iron is given as medicine it acts indirectly by protect- 

 ing the iron in the nucleoalbumins of the food from destruc- 

 tion (p. 186). 



Protein is first of all a tissue builder, and is also a source 

 of energy by its decomposition. A dog can live on lean meat 

 (pure protein) for months and gain in weight. 



Carbohydrates in the food, as sugar and starch, are 

 digested in part by the salivary ferment (ptyalin), but chiefly 

 by the pancreatic ferment (trypsin) in the intestines, and are 

 converted by them into glucose. The glucose is then 

 absorbed by the small intestines, passes thence into the 

 enterohepatic circulation and is oxidized within the liver 

 cells with the production of heat equivalent to 1,657 kilogram 

 meters for each gramme of carbodydrate consumed, while 

 carbon dioxide and water are formed as end-products. The 

 heat production, as in the case of the combustion of proteids, 

 is of great importance in sustaining nerve action. 



Animal fat in the food is emulsified by the bile and by 

 the pancreatic and intestinal secretions and is absorbed by 

 special cells of the intestinal mucous membrane and passes 

 into the lymphatics ; thence into the thoracic duct and 

 eventually appears to be taken up by the pulmonary alveoli 

 and there oxidized into carbonic dioxide and water with 

 production of heat. 



