PHYSIOLOGICAL RELATIONS OF BELLADONNA 381 



Elimination.— BeUhdomia, is eliminated by the kidneys 

 and bowels; traces have been found in the milk. It is, 

 however, chiefly oxidized in the body. 



Summary:— It will be observed that belladonna, gener- 

 ally speaking, first stimulates and then depresses the nerve 

 centres, while it chiefly paralyzes the mx)tor nerve termina- 

 tions, including the inhibitory (vagus and splanchnic), the 

 secretory (chorda tympani, etc.), and, to a less extent, the 

 sensory nerves. Secondary depression of the cerebrum is 

 not so profound as that of the great medullary centres, 

 especially the respiratory centre, and there is sometimes a 

 slight and brief stimulation of the motor nerves of the 

 smooth muscles, viz., vagus, splanchnic, and possibly vaso- 

 motor nerves. 



Full medicinal doses depress the peripheral filaments 

 of the inhibitory and secretory nerves and the motor 

 nerves of the unstiiped muscles, as well as the muscles 

 themselves, lessen the functional activity of the volun- 

 tary motor system, and, to a less degree, that of the 

 afferent nerves. The pulse becomes quickened because of 

 paralysis of the peripTieral vagus endings and stimulation of 

 the heart or its ganglia; the bloo4 tension is augmented 

 because of the increased cardiac action and stimulation of 

 the vasomotor centres; and the respiration is accelerated 

 because of excitation of the respiratory centres. The 

 temperature is elevated owing to the circulatory, exaltation 

 and stimulation of the heat-producing centres. Slight 

 delirium may be present from the exciting action of the 

 drug upon the cerebral motor centres. 



The spinal cord is unaffected by therapeutic doses. 

 Locally applied, belladonna is a direct paralyzant to nerves, 

 muscles, vessels and cells. 



PHYSIOLOGICAL EELATIONS OF BELLADONNA TO OTHER DRUGS. 



A medicinal dose of atropine stimulates, while morphine 

 depresses, the brain, respiratory functions, and intestinal 

 peristalsis. This antagonism ceases when poisonous doses 



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