NERVOUS PATHWAYS IN THE CHEMICAL 
REGULATION AGAINST COLD AND THEIR CENTRAL 
CONTROL 
J. Chatonnet 
Faculte Mixte 
de Medecine et de Pharniacie 
Universlte de Lyon 
France 
The nervous system can activate heat production in various 
ways, at least theoretically. Three main processes are usually 
called upon. First, the nervous system can increase the specific ac- 
tivity of every innervated organ; mechanical activity of muscle is 
a good example of this. The heat production will increase according- 
ly, the useful work being very small in the case of muscular tonus 
of shivering. Second, there are nonspecific reactions of emergency 
function, which, though they are not directly adapted to the struggle 
against cold, spend energy and produce heat useful for this purpose. 
An example of this is the activation of the sympathetic system and 
epinephrine secretion. Finally, there exists a specific and indepen- 
dent system which activates metabolism and heat production by 
various organs, especially the liver and splanchnic viscera, without 
any other efficient activity. 
Although the roles of these various means have often been in- 
vestigated in the past, only few works are at the present directed 
in this line; however, no definite solution has been found yet. We will 
consider the problem from the standpoint of the quantitative impor- 
tance of each of these factors and the conditions under which they 
are put into action. 
Most investigators are concerned with the disturbances of the 
central temperature after excluding one of the effector mechanisms. 
Such a method cannot provide sufficient and quantitative information. 
Also, the estimation of the heat production itself is not of much use 
in many cases. Indeed, the caloric response to cold depends more 
or less on physical regulation, chiefly on peripheral vasomotor 
activity, and it would be preferable if it were suppressed before- 
hand. Besides, one must be sure that the intensity of the cold 
action is responsible for the development of the caloric response 
as it may be the result of an increase of heat loss. Finally, a 
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