DIGESTION 



129 



sion of the digestive canal, and is a most important organ 

 of digestion. It is a hollow, pear-shaped pouch, having 



a capacity of three pints, 

 in the adult. Its walls 

 are thin and yielding, and 

 may become unnaturally 

 distended, as in the case 

 of those who subsist on 

 a bulky, innutritions diet, 

 and of those who habit- 

 ually gormandize. 



26. The stomach has 

 also two openings; that 

 by which food enters, 

 being situated near the 

 heart, is called the car- 

 diac, or heart orifice ; the 

 other is the pylorus, or 

 "gatekeeper," which 

 guards the entrance to the 

 intestines, and, under ordi- 

 nary circumstances, per- 

 mits only such matters to 

 pass it as have first been 

 properly acted upon in the 

 stomach. Oojp^ buttons, and the like are, however, readily 

 allowed to pass, because they can be of no use if retained. 

 The soft and yielding texture of this organ the stomach 

 indicates that it is not designed to crush and break up solid 

 articles of food. 



27. The Gastric Juice. We have seen how the presence of 

 food in the mouth excites the salivary glands, quickly causing 

 the saliva to flow. In the same manner, when food reaches 

 the stomach, its inner lining, the mucous membrane, is at 



26. Heart orifice? Gatekeeper? Coins, etc. ? Indication of the soft and yielding text- 

 ure of the stomach ? 



27. What is meant by the gastric juice ? 



FIG. 28. SECTION OF CHEST AND ABDOMEN 



A, Heart E, Gall Bladder 



B, The Lungs F, Stomach 



C, Diaphragm G, Small Intestine 



D, The Liver H, Large Intestine 



