The Emergency Function 

 of the Suprarenal Medulla 



W. B. CANNON 



BOSTON 



Introduction 



A point of prime importance in the functioning of the suprarenal 

 medulla is its subjection to central nervous influences coming to it by way 

 of the splanchnics. With a variety of methods, in the hands of various 

 investigators, proof has been brought that artificial stimulation of the 

 splanchnic nerves will induce secretory activity in the medullary portion 

 of the suprarenal gland, and that in consequence epinephrin is increased 

 in the blood. Thus the fact is now securely established that there exists 

 in the body a mechanism by which this endosecretory gland can be made 

 to discharge its products promptly into the circulation. 



The splanchnic nerves belong to the sympathetic division of the 

 autonomic system, that portion of the nervous organization of an animal 

 that is brought into action during great emotional stress and during as- 

 phyxia and painful stimulation. Under such conditions, from one end of 

 the body to the other, there is evidence of nervous discharges via, the sym- 

 pathetic. In the cat, for example, the hairs rise on the head, back and 

 tail, the activities of the stomach and intestines are inhibited, and there 

 is widespread vasoconstriction. With such general involvement of the 

 sympathetic division in activity do the splanchnic fibers distributed to 

 the suprarenal medulla participate ? Is there discharge, or increased dis- 

 charge, of epinephrin in these circumstances ? 



The answer to these questions is important for several reasons. First, 

 because epinephrin by itself and in very small amounts can induce impor- 

 tant changes in the body ; second, since epinephrin has the same effects on 

 the viscera as do sympathetic nerve impulses, it would, if specially secreted 

 in times of stress, cooperate with those impulses; third, special secre- 

 tion would justify the existence of acknowledged secretory nerves; and 

 fourth, since function is associated with action, the circumstances inducing 

 a special secretion of the suprarenals would properly suggest their normal 

 functions. 



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