62 SCIENCE OF HOME AND COMMUNITY 



the body. The process of digestion begins in the mouth, 

 where the saliva acts on the starches, changing them into 

 sugars. In the stomach the gastric juice acts on the pro- 

 tein, changing it to a soluble form known as peptone. The 

 food is thoroughly worked over here and reduced to a fine 

 semi-liquid state before it passes on to the small intestines. 

 Just after the food leaves the stomach it comes in contact 

 in the small intestines with the pancreatic juice, which has 

 the power of digesting all three kinds of nutrients. It 

 finishes the work begun by the saliva in digesting the starches, 

 and that begun by the stomach in digesting the proteins, 

 and in addition, with the aid of biTe, it digests the fats. 



Absorption of foods. After the foods are digested, they 

 are absorbed through the walls of the intestines and carried 

 by the blood to the various parts of the body, where they 

 are used. The waste products resulting from the oxidation 

 of foods are given off by the various excretory organs of the 

 body. The carbon dioxid and some of the water resulting 

 from the burning of the food pass off through the lungs. 



Exercise and digestion. The subjects of exercise and 

 digestion are closely related. One of the chief values re- 

 sulting from exercise lies in the beneficial results which it 

 has on the process of digestion. It is a well-known fact that 

 those people who are doing heavy muscular work are less 

 afflicted with digestive troubles than those who secure little 

 muscular exercise. People who change their occupations 

 or habits to those which require less muscular effort often 

 find that their general health is much poorer. It is specially 

 important for those living a sedentary life that some form of 

 exercise should be taken regularly to insure the proper work- 

 ing of the digestive system as well as of the other systems of 

 the body. 



Our first answer to the question as to what kinds of food 

 we need is that we must have foods which furnish enough 

 of the proteins to build up and repair our body tissues and 



