SUMMARY 369 



The mouth contains salivary glands, which secrete saliva. Saliva 

 contains a ferment, ptyalin. 



Ferments, or enzymes, are substances that by their presence bring 

 about chemical changes. 



The teeth crush the food, and mix it with the saliva. 



Food is swallowed by the action of the muscles of the tongue, 

 pharynx and esophagus. 



Food enters the stomach from the esophagus, and leaves it at the 

 pylorus opening, entering the small intestine. 



Gastric juice contains the ferments rennin and pepsin, and hydro- 

 chloric acid. Pepsin begins the digestion of proteids. 



Digestion in the small intestine is carried out by the secretions of 

 3 glands. The intestinal glands secrete the intestinal juice. The 

 liver secretes the bile. The pancreas secretes the pancreatic juice. 



The pancreatic juice contains the ferments amylopsin, steapsin, and 

 trypsin; these complete the digestion of carbohydrates, fats, and pro- 

 teids, respectively. Intestinal digestion takes place under alkaline 

 conditions. 



Absorption in the small intestine takes place through the villi; 

 these contain blood tubes and lacteal glands. 



The object of digestion is (1) to get the food into soluble form, and 

 (2) to get the large molecules of food substances into smaller molecules 

 that can recombine to form the molecules actually needed by the cells. 



Assimilation is the bringing together of food, oxygen, and 

 the cells. 



Food is stored as glycogen (in the liver), and as fat. The stomach 

 acts as a temporary storage organ. 



Dietetics is the science of our diet. We need a " balanced" diet, 

 containing the best possible proportions of cell-building and of energy- 

 producing material. 



Good cooking and good serving are as important as proper kinds of 

 food. 



Indigestion is often the result of our own carelessness. 



Alcohol coagulates the proteids, and makes their digestion hard; it 

 therefore brings on stomach indigestion. It interferes with the action 

 of the liver, so that body wastes are left in the blood. 



