184 



THE INTERNAL ENVIRONMENT OF THE BODY 



Part III 



food entering. 



.course of food after 

 / final mostication 



esophagus 



2 reticulum 

 (tripe) 



— 3 omasunn 



4 obomasum 



I rumen 

 "fermentation vot" 



esophagus 



diaphragm 



3 omasum 

 "filter press" 



2 reticulum 

 agitator 



lining-tripe 



4 abomasum 

 ( true stomach ) 



Fig. 11.14. The pouches and stomach of a cow, a cud chewer or ruminant. 

 Three pouches, all enlargements of the esophagus, compose the rumen (capacity 

 120 or more liquid quarts), the reticulum, and the omasum; the true stomach is 

 called the abomasum. In the upper figure the course of the food after its first 

 swallowing is shown by long dashes and arrows. The second swallowing, after the 

 cud has been chewed, is indicated by short dashes and arrows. In the lower figure 

 the pouches and stomach are in their natural position. 



its crop automatically delivers the corn and grass to the glandular and grind- 

 ing sections of its stomach (Fig. 36.15). 



Function of the Stomach. The human stomach is a J-shaped enlargement of 

 the digestive tube with a muscular wall and a glandular lining. Its anterior end 

 closes by the contraction of a ring of muscle (cardiac valve) and its posterior 

 end by another ring (pyloric valve). Its muscular movements are con- 

 trolled by the nerves of the autonomic system; the vagus nerve, partly 

 parasympathetic, stimulates contractions, and the sympathetic nerve inhibits 



