96 HUMAN PHYSIOLOGY. 



COMPOSITION OF CEREAL FOODS. 



DIGESTION. 



Digestion is a physical and chemic process by which the food intro- 

 duced into the alimentary canal is liquefied and its nutritive prin- 

 ciples are transformed by the digestive fluids into new substances 

 capable of being absorbed into the blood. 



The digestive apparatus consists of the alimentary canal and its 

 appendages viz., teeth ; salivary, gastric and intestinal glands ; liver ; 

 and pancreas. 



Digestion may be divided into seven stages: prehension, mastica- 

 tion, insalivation, deglutition, gastric and intestinal digestion, and 

 defecation. 



Prehension, the act of conveying food into the mouth, is accom- 

 plished by the hands, lips, and teeth. 



MASTICATION. 



Mastication is the trituration of the food, and is accomplished 

 by the teeth and lower jaw under the influence of muscular contrac- 



