216 



ELEMENTS OF PHYSIOLOGY 



4. The microscope shows the coating on the bread to be 

 a vegetable growth. If it forms on the walls of the stomach, 

 it may extend to what ? 



III. Stomach A che. 



1. How can you tell whether fruit preserved in a sealed 

 glass jar is spoiling ? 



2. What connection is there between belching at times 

 after eating too freely of sweet or starchy food and the 



observation above ? 



3. Why does belching sometimes 

 give relief to an uneasy stomach ? 



4. Can you, by using these facts, ex- 

 plain a cause of stomach ache ? 



Be ready to give logical explanation 

 in class, of cause of bad breath, furred 

 tongue, and stomach ache. 



386. The Small Intestine. When 

 the chyme passes the pylorus, it enters 

 the small intestine, which is a tube 

 about as large around as the thumb, 

 and about thirty feet long, lying coiled 

 in the central part of the abdominal 

 cavity. The first part of it, about ten 

 inches in length, is called the duodenum 

 (from a word meaning twelve, because 

 its length is twelve fingers' breadth) (Fig. 167). The 

 mucous and submucous coats of the small intestine are 

 wrinkled by numerous folds which are crescent-shaped, 

 since no single fold goes entirely around the tube (Fig. 

 171). The folds are so numerous that they occupy almost 

 the entire inner surface. The small intestine is the chief 

 organ of absorption as well as of digestion, and the ab- 

 sorbing surface is greatly increased by the folds. On and 

 between the wrinkles are innumerable tiny projections called 

 villi (Fig. 172). Each villus contains a loop of blood 



FIG. 171. A Portion of 

 Small Intestine cut 

 open to show the Folds 

 on its Inner Surface. 



