160 PHYSIOLOGY. 



If the food taken be all ready to build tissue, for exam- 

 ple, certain forms of sugar, liquid, soluble, and of the 

 proper chemical composition, it will not need to go through 

 these changes. 



In order to understand the process of digestion let us 

 first turn our attention to the anatomy of the organs of 

 digestion. 



The Organs of Digestion. The organs of digestion 

 are the digestive tube and the accessory parts, the masti- 

 catory organs, the glands in, and alongside of, the walls 

 of the tube. 



The parts of the digestive tube are the mouth, the 

 pharynx, the gullet (or esophagus), the stomach, the small 

 intestine, the large intestine. 



Brief Description of the Digestive Organs. At the 

 back of the mouth may be seen the soft palate with the 

 cylindrical uvula hanging from its center. Beyond this 

 is the cavity of the pharynx, which narrows below into 

 the gullet, a red-walled, muscular tube, extending along 

 the dorsal side of the windpipe, and close to the spinal 

 column. It extends the length of the thorax, and then 

 passes through the diaphragm and widens into the stomach, 

 at the upper left end of the latter. The stomach is some- 

 what pear-shaped, with the larger end to the left. At the 

 right end it tapers into the small intestine, the first foot 

 or so of which is called the duodenum. Then comes a 

 long coil of the small intestine, which joins the shorter 

 large' intestine, ending in the rectum. Just below the 

 diaphragm is the dark-colored liver, overlapping a large 

 portion of the stomach. Between two of the lobes of the 

 liver is the bile sac whose duct enters the duodenum a 

 short distance from the stomach. The pancreas is a pink- 



