HEALTH AND DISEASE 



6 lbs. to 14 lbs., the increase being entirely clue to the saliva with which 

 they have become impregnated. The mixed saliva, or saliva resulting from 

 the mixture of the fluid secreted by the several glands, is an opalescent 

 liquid with a specific gravity of about 1005; it is alkaline to test-paper, 

 and contains a special ferment named ptyalin, the properties of which will 

 be discussed when the process of digestion of food is under consideration. 



Deglutition. — After the food has been masticated it is rolled by the 

 tongue into a kind of ball and pressed back- 

 ward against the palate till it is seized by 

 the muscular walls of the pharynx and trans- 

 mitted to the oesophagus or gullet, by which 

 it is conducted to the stomach. In this 



Stomach Laid Open 



A, Left half. B, Eight half, c. Cardiac orifice or entrance. D, 

 Pyloric orifice or exit. K, Duodenum. F, Bile duct and pancreatic 

 duct opening into the duodenum. G, Lesser curvature. H, Greater 

 curvature'. 



Fig. S3.— Peptic Gland 



a, i Opening through which gas- 

 tric juice is discharged into the 

 stomach; - divisions of the main 

 duct. 



B, > Parietal cell: - central cells. 



course there is a critical moment when the bolus is passing over the 

 opening of the trachea or windpipe, and the most carefully -regulated 

 action of many muscles is required to prevent its entry into the larynx 

 or trachea on the one hand and into the nose on the other. 



The Stomach is a well-defined segment of the alimentary canal which 

 intervenes between the oesophagus or gullet and the small intestine. Seen 

 from behind it presents the relations shown in the adjoining wood-cut 

 (fig. 81), having the liver in front, the spleen to the left, and the pancreas 

 above. Its average capacity is 14 quarts, and it weighs about 3^ lbs. The 

 food enters by an opening on the left of the middle line termed the cardiac 

 orifice, and leaves by another on the right side called the pylorus or pyloric 



