ELEMENTARY PHYSIOLOGY 



QUESTIONS ON LESSON XVIII. 



t. Describe the form, size, position, and structure of the oesophagus. 



2. Describe the action of the parts concerned in the act of swallowing. Tc 



what extent is this a voluntary action ? 



3. Describe carefully the action of the muscular fibres of the oesophagus 



during deglutition. 



4. What is the cause of the difficulty sometimes experienced in swallowing a 



pill ? 



5. Describe the structure of the walls of the stomach. 



6. By what means is the food kept in motion during gastric digestion ? 



Describe this motion. What purpose is served by this motion ? 



7. Describe the general appearance of the mucous membrane of the stomach 



(i) When the organ is empty, and (2) When food is introduced. 



8. Describe the general characters and composition of the gastric fluid. 



9. What is the action of the gastric fluid on (i) starchy fluids, (2) nitrogenous 



foods, and (3) fats ? 



10. What is pepsin ? What is its use ? How may it be obtained ? 



1 1. What is chyme ? Of what does it consist ? 



12. Describe fully the various changes which take place in the food while in 



the stomach. 



13. Explain the term chymification. . 



14. What are peptones ? Where and how are they formed ? How do they 



differ from the materials from which they are produced ? 



LESSON XIX. 

 THE INTESTINES AND INTESTINAL DIGESTION. 



THE general form and arrangement of the intestines have been 

 described in Lesson XIII. 



Both large and small intestines, like the stomach, consist of 

 four coats. These coats also correspond with those of the stomach, 

 being arranged as follows ; 



1. Outer serous coat, formed by the peritoneum. 



2. Muscular coat, composed of 



(a) External longitudinal fibres and 



(b) Internal circular fibres. 



3. Areolar layer. 



4. Mucous membrane, forming the interior surface. 



The mucous membrane of the small intestine is in part drawn 

 up into folds, like that of the stomach, but to such an extent that 

 they do not disappear when the tube is distended. These folds 

 are called the valvulae conniventes. They serve to increase the 

 area of the secreting surface, to prevent the food from passing too 

 rapidly through the intestine, and to assist the mixing of the food 

 with the digestive fluids which are poured into the intestines. 



