How Our Bodies Digest Food 403 



salivary glands. The intestinal juice is made in the intestinal 

 glands, which are in the walls of the small intestine. 



The first of the large glands mentioned is the pancreas, a 

 wedge-shaped organ about six inches long and one inch wide. 

 It lies behind the stomach and secretes the pancreatic juice. 



The liver, the second gland, is the largest in the body. It is 

 a dark-red mass, lying on the right side of the body under the 

 lowest ribs, and consists of several lobes. It secretes a yellowish 

 fluid, called bile, and is connected with a bag-like organ, called the 

 gall bladder, which stores the bile. The liver changes sugar, which 

 it absorbs from the blood, into a form of grape sugar called 

 glycogen, and stores it for use in supplying energy for the con- 

 traction of body muscles. The liver also acts as an excretory organ 

 by throwing off poisonous substances with the bile. 



The Pancreatic Juice. The pancreatic juice contains three fer- 

 ments or enzymes which do a great deal toward making the food 

 soluble. Its ferments are trypsin, which acts on undigested albu- 

 min ; amylopsin, which acts upon starch ; and steapsin, which acts 

 upon fat. In these processes the partly digested food is changed 

 into an alkaline condition. 



Bile and Intestinal Juice. The bile and the intestinal juice 

 meet the chyme, or food sent from the stomach into the small 

 intestine, and act upon it. Peristaltic action here helps to mix 

 the food and the juices. 



The most important use of the bile is in breaking up fats so 

 that the steapsin may act more readily upon them. The intestinal 

 juice neutralizes the acids that form as a result of chemical changes 

 in the intestine, and aids a little in digestion. 



After the action of these three fluids, the food is called chyle, 

 instead of chyme, and is now in soluble form, ready to be absorbed 

 through the mucous membrane of the alimentary canal and the 

 capillary walls into the blood, which carries it to the cells. 



The Large Intestine. The large intestine, the last part of 

 the alimentary canal, is a tube five or six feet in length whose 

 chief function is the removal of waste material from the body. 

 One region of this canal has a worm-like extension, known as the 

 vermiform appendix, which is the seat of the disease called appen- 



