36 GENEllAL ACTIONS OF DRUGS 



(b) Drugs increasing the rate of heart-beats. 



Belladonna Stramonium 



Atropine Cocaine 



Hyosoyamus 



(c) Drugs increasing the 'force and rate of heart-bea^s. 



Alcohol Strychnine 



Chloroform Caflfeine 



Ether Quinine 



Ammonia Arsenic 

 Ammonium carbonate 



(d) Drugs decreasing tJie force and rate of the heart-beats. 



Aconite Prussic acid 



Veratrum viride Ergot 



Antimony salts 



The drugs most frequently given to animals for their 

 action on the heart are alcohol, ether, digitalis, strophanthus, 

 ammonia, ammonium carbonate, camphor, caffeine, strych- 

 nine, atropine, aconite and veratrum viride. The reader is 

 referred to special articles on these drugs for therapeutical 

 indications and other details. 



III. — Drugs Acting on the Blood "Vessels. 



The following table includes the mechanism regulating 



vascular tension : 



( Smooth muscular fibres 

 1. In the walls of the vessels. < Terminations of vasodilators and vaso- 



( constrictors 



3. Nerve supply Of vessels. . . . j ^-^Sri^.^ors 



' Vasomotor centres In the medulla and 

 subsidiary centres in the spinal 

 3, Centres -j cord and sympathetic system, con- 

 trolling the vasodilating and con- 

 stricting nerves 



Each vessel is governed by two sets of fibres, — the 

 constricting and dilating, — but we cannot discriminate 

 between the action of a drug on the muscular fibres and the 

 peripheral nerve endings in the vessel walls ; nor can we 



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