DIGESTION OF FOOD: THE (ESOPHAGUS 



01 



which it enlarges into a good sized organ, the stomach, lying 

 a little to the left of the middle line; Fig. 46. The stomach 

 is pear-shaped and lies with the small end pointing obliquely 

 downward, and to the right. When moderately full it is 

 about ten inches long, by four wide and deep, and holds about 

 three pints. The entrance of the oesophagus is on the upper 

 side, about the middle of its length, and is commonly closed 

 by a muscular ring, 



the cardiac valve; Fig. / \. an Qdder 



48. This prevents the 

 food from going up 

 the oesophagus again, 

 while the stomach is 

 contracting about it. 

 Sometimes, when 

 there is too much 

 food in the stomach, 

 or when the food does 

 not digest well, this 

 valve opens and a re- 

 versal of the muscu- 

 lar action forces the FlG ' ^--DIAGRAM F THE STOMACH AND 



. , , , , , INTESTINE LAID OPEN 



back through ghowing the relation of ducts of Uver ^ pancreaa 



the OeSOphagUS tO the to one another and to intestine. 



mouth. This is vomiting and occurs most frequently in babies, 

 in which case the cause is, generally, too much food. With 

 adults, vomiting and nausea usually occur only when the 

 stomach is disturbed by food which does not properly digest. 



From the small end of the stomach, called the pyloric end, 

 starts the first section of the intestine, the opening into it 

 being guarded by the strong, circular, muscular pyloric 

 valve; Fig. 48. 



The cavity of the human stomach is one continuous space, 

 though in some lower animals which " chew the cud," as we 

 say, there are four divisions in it; Fig. 49. In the camel, 



