BIOLOGY 

 LIBRARY 



G 



Reprinted from THE AMERICAN JOURNAL OF PHYSIOLOGY 



Vol. 60, No. 1, March, 1922 



AN ANALYSIS OF THE NERVOUS CONTROL OF THE CAR- 

 DIOVASCULAR CHANGES DURING OCCLUSION 

 OF THE HEAD ARTERIES IN CATS 



CORA SENNER WINKIN 



From the Department of Physiology, Columbia University 



Received for publication November 4, 1921 



STATEMENT OF THE PROBLEM. 1 The relations dealt with in this 

 study are the cardio-vascular relations found in the mammalian or- 

 ganism under extreme conditions of stress. The procedure of the ex- 

 periments, occlusion of the head arteries, gives a complete anemia of the 

 brain, and thus produces a profound change in the internal environment 

 of the animal. To this the mammal tends to respond by a series of 

 vigorous reactions. These reactions, moreover, seem to go in a direc- 

 tion opposite to that of the change in internal conditions of a par- 

 ticular group of cells. Thus, with an asphyxial accumulation of carbon 

 dioxide in the medium surrounding the critical medullary cells, there 

 is released an entire series of reactions which, could they all be carried 

 to completion, would reduce the tension of this gas in the body fluids 

 of the cerebral region. Prominent among these reactions is a great and 

 prolonged rise of blood pressure, involving the extreme resources of the 

 organism, tending to send a greater volume of blood to the anemic 

 regions, and hence to decrease the concentration of the carbon dioxide 

 in the nerve cells of the medulla oblongata. In the cat, this anemic 

 rise of blood pressure can be well controlled anatomically, and is suscep- 



1 A preliminary note has been published in Proc. Soc. Exper. Biol. and Med., 

 1921, xviii, 155. 



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THE AMERICAN JOURNAL OP PHYSIOLOGY, VOL. 60, NO. 1 



4787 t 6 



