8 4 



HUMAN PHYSIOLOGY 



CHAP. 



Cardiac 



pushed along through the oesophagus into the stomach. 

 A similar muscular action occurs in the other organs of 

 the alimentary canal. 



72. Stomach Digestion. The stomach is the greatest 

 enlargement of the alimentary canal, being about ten 

 inches long and from four to six inches across and hav- 

 ing a capacity of about four pints. It is located just 



below the diaphragm, 

 with the larger end 

 (the fundus) to the 

 left side. It has an 

 opening for the food 

 from the oesophagus 

 to enter, called the 

 cardiac orifice, and 

 one for the food to 

 pass out into the in- 

 testines, called the 

 pyloric orifice. These 

 FIG. 4 6. -Outside of the stomach, front openings are carefully 



view. (From Heitzmann's "Anatomy." guarded by Strong, 



circular muscles, so 



that after the food enters the stomach it cannot leave 

 until it is thoroughly digested. Then the pylorus re- 

 laxes, and the mass slowly enters the intestines. 



The stomach differs from the other organs of the 

 digestive tube in that it has tJirce layers of muscles 

 instead of two; the longitudinal on the outside, the 

 circular next, and the oblique or transverse on the in- 

 side. The mucous lining is quite thick because it is 



