How Our Bodies Digest Food 407 



The mouth is the cavity where the food is chewed by the teeth, 

 mixed with saliva and reduced to a pasty mass. The saliva changes 

 some of the starchy food to sugar. 



From the mouth the food passes through the pharynx and the 

 esophagus into the stomach. 



The stomach is a muscular bag covered with a thin, shiny 

 membrane, called the peritoneum, and lined with a soft, moist 

 substance, called the mucous membrane, in which are glands that 

 secrete gastric juice. 



The gastric juice partially digests the protein food. It has 

 no action upon starchy and fatty foods. 



In the small intestine food is further digested by the pan- 

 creatic juice, aided by the action of the bile and the intestinal 

 juice. 



The large intestine performs the last part of the digestive 

 process, the excretion of waste material. It is often a breeding 

 place for bacteria. 



Absorption is carried on by osmosis the passage of a liquid 

 through a membrane. It begins in the stomach, but is largely 

 accomplished in the small intestine. 



FACT AND THOUGHT QUESTIONS 



1. Name the parts of the alimentary canal. 



2. Describe the structure of the stomach. 



3. How is the small intestine equipped to perform its work? 



4. Give the function of the gastric juice; of the saliva. 



5. Name the kinds of teeth. 



6. Give the number and the location of each kind of teeth in an adult. 



7. Describe the structural adaptations of each kind of teeth. 



8. Describe an experiment to show digestion. 



9. From what part of the alimentary canal is most of the digested food 

 absorbed ? 



10. Tell how peristalsis takes place in the alimentary canal and what effect 

 it has on digestion. 



11. Why does the taste of the food we place in our mouths change, or even 

 disappear, as we chew? 



12. Through how many "doorways" does food pass from mouth to intes- 

 tines ? 



13. Name some article of food you ate for breakfast and tell what the 

 body had to do to it to benefit from it. 



