CHAPTEK VII 

 THE APPLIED PHYSIOLOGY OF DIGESTION 



Digestion in the Mouth. 



THE object of digestion in the mouth is to convert the 

 food into a mechanical form in which it can be easily 

 swallowed. By means of the teeth the solid part of the 

 food is broken up and reduced to a state of fine division, 

 in which form it is easily attacked by the gastric juice. 

 It can therefore be readily understood how imperfect 

 chewing, brought about either by bolting the food or by 

 a defective dental apparatus, impedes gastric digestion, 

 and by allowing the entrance of lumps of food into the 

 stomach which irritate its walls is a frequent cause of 

 gastritis. 



By means of the saliva dry food is moistened, and the 

 bolus which results from chewing is lubricated with 

 mucus and rendered fit for swallowing. That the mere 

 moistening of the food is one of the chief objects of 

 salivary secretion is shown by the experiments of 

 Pawlow, which have demonstrated that a much larger 

 secretion of saliva is called out by the introduction into 

 the mouth of dry substances than by those that are 

 moist. 



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