QUESTIONS AND ANSWERS 119 



In the ox, about the same relation exists between the two as in 

 the horse, but the glands of the pylorus are poorer iq pepsin than 

 those of the fundus. 



Name the different digestive ferments in the gastric secretion of the 



mature horse and the different proximate food principles 



that they digest. State how this action is affected in each 



case by acidity and alkalinity, respectively. 



Pepsin acts on proteid matter and can only do so in an acid 



medium. The gastric secretion is said by some to contain an 



amylolytic ferment ; at any rate, the saliva swallowed with the food, 



this ferment, or both convert starch into sugar in the stomach and 



can only act during the early part of stomach digestion while the 



reaction is alkaline. 



What produces the sensation of (a) hunger, (b) thirst? 



(a) Hunger is referred to the stomach, but the reason why is 

 not known. The pneumogastric nerves may be divided but the sen- 

 sation of hunger remains. The stomach may be full or empty and 

 hunger still exist. 



(b) Thirst is referred to the pharynx. A deficiency of mois- 

 ture in the system is always shown by a dryness of the pharynx and 

 palate. Nothing is known of the nervous apparatus involved in 

 thirst. 



Describe peristaltic action. How is it accomplished ? 



Peristaltic action is the worm-like movement by which the ali- 

 mentary canal propels its contents. It consists of a wave of contrac- 

 tion passing along the tube, anteroposteriorly. It is accomplished 

 by the contraction of its circular and longitudinal muscular fibres. 



Mention the glands of the intestinal canal and state their function. 



Lieberkiihn's andBriinner's glands secrete a mucous fluid which 

 contains enzymes as follows : succus entericus, enterokinase, erepsin, 

 inverting ferments (invertase, maltase, lactase). These enzymes 

 have very important digestive actions. 



State the difference between chyme and chyle. 



Chyme is the liquid mass into which the food is converted by 

 gastric digestion. It is a yellow, frothy, precipitated, slimy fluid, 

 which in the anterior part of the intestinal canal possesses a peculiar, 

 mawkish smell, and in the ileum, a distinctly fecal odor. In the 

 ileum, the contents are considerably less fluid. 



Chyle is the milky fluid taken up by the lacteals from the chyme 

 in the intestines. It is a turbid, alkaline fluid, containing fat 



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