CHAPTER V 

 DIGESTION OF FOOD IN THE MOUTH 



64. Food and digestion. Albumin, fat, and sugar are 

 continually being oxidized in the body, and the products 

 of oxidation, together with mineral matter and water, are 

 being thrown off. In order to keep up the strength and 

 form of the body a constant stream of new material must 

 be supplied. 



Anything which, taken inside of the body, supplies it with 

 weight, heat, or energy is food (see pp. 64 and 89). 



In preparation for the use of the body, food is reduced to a form which 

 can be dissolved in water, and drawn through the walls of the blood 

 tubes. The blood distributes it to all parts of the body. The process 

 of producing a chemical change in food so that it can be taken up by 

 the blood is digestion. 



Man uses as food a combination of albumin, fat, sugar or starch, 

 mineral matters, and water, which are identical with the proximate prin- 

 ciples of the body. Of these water and mineral matters can enter the 

 blood without being changed, while the albumin, fat, sugar, and starch 

 require digestion. Albumin is changed to a form called peptone, which 

 can easily diffuse through the walls of the blood tubes, and so become 

 a part of the blood. 



Sugar and starch are both changed to glucose, a form of sugar found 

 in the grape. Fat is saponified and emulsified. 



65. Cooking. Digestion is begun by applying heat to 

 food, either with or without water. Preparing food by 

 heat is cooking. The heat of cooking coagulates the 

 albumin. It also softens and dissolves the connective 



