FOOD AND DIGESTION 



105 



breaks up the fats into tiny globules. Fat in small glob- 

 ules floating in a liquid is called an emulsion; fresh milk 

 is an emulsion of cream (Fig. 98). Fat is not changed 

 to another substance 

 by digestion, but it is 

 emulsified, and in this 

 condition it readily 

 passes through the 

 walls of the intestines 

 and is absorbed by 

 the lymphatics called 

 lacteals (colored Fig. 

 5) found in the villi. 

 It then ascends 

 through the thoracic 

 duct to a large vein 

 at the left side of the 

 neck (Fig. 100). The 

 digested proteid, starch, and sugar pass into the capillaries 

 of the portal vein, and go to the liver on their way to the 

 general circulation (Fig. 100). The portal circulation 

 empties into the large ascending vein leading to the 

 right auricle (Fig. 100). 



The Liver. This large, chocolate-colored gland is located just 

 beneath the diaphragm on the right side (Fig. 90, colored Fig. 6). It 

 is on a level with the stomach, which it partly overlaps in front. The 

 liver has three important functions: (i) // is a storeroom', digested 

 sugar and starch are stored in it as a substance called liver starch (or 

 gly'cogen). (2) It is a guardian, and destroys poisonous substances 

 which may be swallowed, and which would otherwise enter the blood. 

 Twice as much morphine or other poison is necessary to kill a man 

 when it is taken by the mouth and passes through the liver as when it 

 is injected through the skin. Alcohol, morphine, coffee, and drugs are 

 partly burned up in the liver. (3) // is a gland, and secretes bile. 

 The bile is made chiefly from waste products and impurities in the 



FIG. 98. JUNCTION OF LARGE AND 

 SMALL INTESTINE. 



