92 



VERTEBRATE RESPIRATION 



^378 



•?oS37A 

 ^g.372 

 gc^37.0 



' 36.8 



36.6 

 60 

 50 

 AO 

 30 

 20 

 1J-30 

 -20 



S--2 



in <1; 



!O-10 



Qj O 



o 



1-10. 





iJ "0 5 10 15 20 25 30 35 AO A5 50 55 60 65 70 75 80 

 Time (minutes) 



Fig. 26. 



The internal temperature near the hypothalamus of a man falls 

 after eating ice. Simultaneous recordings of the sweating from the 

 skin and the heat loss are shown to follow this curve very closely. The 

 skin temperature, however, shows a marked increase when ice is 

 eaten (after Benzinger, 1961). 



ism based upon skin sense organs. The latter are important for 

 the production of more conscious temperature control, which 

 frequently results in movement either of the extremities alone or 

 of the whole animal to a warmer environment. 



The hypothalamus, then, contains the sensory system which 

 detects temperature changes of the blood circulating through the 

 brain and puts into action those mechanisms which increase the 

 loss of heat from the body. It is triggered at a particular tempera- 

 ture (36-9° C. = 98-4° F.) which it tends to maintain with sur- 

 prising accuracy. Localised electrical stimulation or warming of 

 the anterior part of the hypothalamus produces the expected 

 thermo-regulatory responses. Removal of this part of the brain 

 leads to marked fluctuations in body temperature. The mechan- 

 isms whereby the loss of heat from the body is decreased under 



