DRUGS ACTING ON THE SKIN 65 



chafing and superficial inflammation when emollients protect 

 the skin from the natural irritation of the air. 



Demulcents are of value in inflammation of the mucous 

 membrane of the digestive tract, and again in catarrh of the 

 mucous membrane of the upper respiratory tract, because 

 they not only exert a direct sedative influence on the throat, 

 but, either reflexly or in some measure directly, act on the 

 bronchial tubes. Demulcents are often employed to relieve 

 irritation in the urinary tract, but it is difficult to understand 

 how they can there exert a demulcent influence after their 

 decomposition in the alimentary canal and absorption into 

 the blood, since they have never been found in that fluid or 

 in the secretions. 



(C) Drugs Influencing the Secretion of Sweat. 



The mechanism controlling the sudoriparous glands and 

 secretion of sweat, comprises sweat centres in the spinal 

 cord ; secretory nerves proceeding from them with termina- 

 tions in the glands ; the gland cells, and blood vessels of 

 the skin. Any portion of this mechanism may be affected 

 by drugs to increase or diminish sweat secretion. 



(1) Drugs increasing the secretion of sweat, or diarphoretics. 

 They may : 



(1) Stimulate the sweat centres. 



(2) Excite the secretory nerve-endings in the glands. 



(3) Increase the activity of the gland cells. 



(4) Stimulate the vasodilators and increase the vascu- 

 larity of the skin. Stimulation of the secretory and vasodi- 

 lator nerves usually go hand in hand, since they accompany 

 each other in their course to the sweat glands. 



DIARPHORETICS. 



Pilocarpine 



Alcohol 



Spirit of nitrous ether 



Heart stimulants 



External heat 



(Warm drinks) 



Pilocarpine stimulates the gland 

 cells, or secretory nerve-endings. 

 The others act indirectly by pro- 

 moting the vascularity of the 

 skin, and thus the activity of 

 the sweat glands. 



