ORGANS AND PROCESSES OF DIGESTION 



147 



That it is independent of this force, however, is shown by the fact that 

 one may swallow with the esophagus in a horizontal position, as in lying 

 down. 



The Stomach. The stomach is the largest dilatation of 

 the alimentary canal. It is situated in the abdominal cavity, 

 immediately below the 

 diaphragm, with the 

 larger portion toward 

 the left side. Its connec- 

 tion with the esophagus 

 is known as the cardiac 

 orifice and its opening 

 into the small intestine 

 is called the pyloric ori- 

 fice. It varies greatly in 

 size in different individ- 

 uals, being on the aver- 

 age from ten to twelve 



, ., FIG. 68. Gastric Glands. A. Single 



inches at its greatest , r 



gland showing the two kinds of secreting 



length, from four to five cells and tne duct where the gland opens on 

 inches at its greatest to the surface. B. Inner surface of stomach 

 Width, and holding from magnified. The small pits are the openings 

 , , c . Tt f rom tne glands. 



three to five pints. It 



has the coats common to the canal, but these are modified 



somewhat to adapt them to its work. 



The mucous membrane of the stomach is thick and highly 

 developed. It contains great numbers of minute tube- 

 shaped bodies, known as the gastric glands (Fig. 68). 

 These are of two general kinds and secrete large quanti- 

 ties of a liquid called the gastric juice. When the stomach 

 is empty, the mucous membrane is thrown into folds which 

 run lengthwise over the inner surface. These disappear, 

 however, when the walls of the stomach are distended 

 with food. 



