649 



When bile pigments are injected into the blood they are quickly 

 excreted by the liver. An increased destruction of red cells within the 

 body or the injection of hemoglobin is followed by an increased secretion 

 of bilirubin. There is considerable evidence to show that bilirubin is 

 derived from hemoglobin. Hemoglobin is probably disintegrated by the 

 Kupfer cells which line the blood spaces of the liver, its iron is utilized 

 anew, while the hematin is converted into bilirubin. Whipple and Hooper 

 (6) have shown that under certain experimental conditions, tissues other 

 than the liver can form bile pigment from hemoglobin. 



In the large intestine, bilirubin is reduced to urobilinogen and uro- 

 bilin and these are partly re-absorbed and brought to the liver, so that one 

 may speak of a circulation of bile pigments. 



Cholesterol. C 27 H 46 O is a terpene derivative, containing one sec- 

 ondary alcohol group. It is an unfailing constituent of all cells and is 

 excreted in the bile in quantities varying from 0.24 to 0.59 gram per 

 liter (Bacmeister). Rosenbloom(e) has found larger quantities in hu- 

 man bile while Rothschild and Felsen state that 0.08 per cent is the 

 normal concentration. 



Rothschild observed that the cholesterol content of the ingested food 

 had an influence on the cholesterol concentration in the blood and bile. 



Feeding cholesterol to dogs does not increase the cholesterol content 

 of their blood because it is excreted so rapidly in the bile. Bacmeister 

 and his pupils found that feeding proteins and fats increases the cholesterol 

 content of the bile. They also found that in diabetes the hypercholestero- 

 lemia was usually associated with an increase of cholesterol in the bile. 

 In pregnancy the cholesterol in the bile decreases along with an increase 

 of the cholesterol in the blood. These facts indicate that the liver regulates 

 the cholesterol content of the blood. Poisons which destroy red blood 

 cells increase the amount of cholesterol in the bile. The solubility of 

 cholesterol in bile is probably clue to the presence of bile salts with which 

 it forms a soluble compound (Wieland). 



Fat. Gall bladder bile contains an average amount of 8.3 grams of 

 fat per liter. In fatty liver, the fat content of the bile may rise to 20 

 parts per mille. 



Mineral Substances. Besides sodium with which the bile acids are 

 ' united, sodium and potassium chloric!, calcium and magnesium phosphates 

 and iron are found in bile; of the last, there is about 40 to 115 mgs. 

 per liter. 



9 



Tests of Liver Function 



Owing to its size, it is possible for the liver to carry on its functions 

 even when extensively diseased. It is only in diffuse lesions that dis- 

 turbances of function occur. A liver riddled with tumors may carry on its 



