CHAPTER VI 

 THE DIGESTION OF FOOD 



144. The Object of Digestion. The tissues of the body 

 cannot take up and use the food materials in the form 

 in which they exist in the food we eat. They must first 

 be brought into a condition of solution. This is done 

 that they may be absorbed or be able to make their 

 way through the tissues forming the delicate walls of the 

 alimentary canal. 



In the next place, the food materials must undergo cer- 

 tain chemical changes whereby they can be assimilated or 

 taken up by the tissues. 



This most wonderful process by which the food mate- 

 rials are made capable of absorption and assimilation is known 

 as digestion. 



The special organs concerned in bringing about this 

 marvelous change in the food are the digestive organs. 



145. The Alimentary Canal. The food tube from the 

 mouth to the lowest part of the intestines is known as the 

 alimentary canal, because it is for the alimentation, or feeding, 

 of the body. 



Beginning at the mouth, this food tube continues as the 

 gullet, or (Esophagus. It then pierces the diaphragm, which 

 forms the partition between the chest and the abdomen 

 (Figs. 83 and 103). 



Lower down the food tube swells out into a large bag 

 called the stomach. 



100 



