ACTION OF THE SALIVABY GLANDS 



103 



side of the head, and their ducts enter the mouth on the 

 inner side of the cheeks, just about opposite the second 

 upper molar teeth. It is the inflammation and enlarge- 

 ment of these glands that causes the disease known as 

 the mumps. 



The submaxillary glands lie below the two halves of 

 the lower jaw, and their ducts open into the mouth at points 

 near the middle line of the under side of the tongue. 



The sublingTial glands lie under the mucous membrane 

 below the tongue and floor of the mouth. They open into 

 the floor of the mouth by many small ducts. 



Action of the salivary glands. — Each cell of a gland 

 obtains its food sup- 

 ply from the blood 

 vessels, and out of 

 this food it manu- 

 factures the secretion 

 known as saliva. 

 Since the amount of 

 saliva needed to di- 

 gest the food we 

 eat varies with the 

 amount of food pres- 

 ent in the mouth, it 

 is evident that the 

 secretion of the cells 

 must be imder con- 

 trol. In this respect 

 the glands are like a 

 factory whose output is regulated to meet the conditions of 

 supply and demand. In the case of the cells this control 

 is exercised by nerves whose general arrangement is indi- 



Fxa. 30 - 



Relation of salivary glands to the 

 moiitli cavity. 



