ENERGY SUPPLY OF THE BODY 193 



ing on the vital processes. All parts of the body, through 

 oxidation, furnish heat. Active organs, however, such as 

 the muscles, the brain, and the glands (especially the liver), 

 furnish the larger share. The blood in its circulation serves 

 as a heat distributer for the body and keeps the tempera- 

 ture about the same in all its parts (page 33). 



Next to the production of heat, in the consumption of 

 the body's energy, is the production of motion. This 

 topic will be considered in the study of the muscular 

 system (Chapter XV). 



Some Questions of Hygiene. The heat-producing ca- 

 pacity of the body sustains a very important relation to 

 the general health. A sudden chill may result in a num- 

 ber of derangements and is supposed to be a predisposing 

 cause of colds. One's capacity for producing heat may be 

 so low that he is unable to respond to a sudden demand 

 for heat, as in going from a warm room into a cold one. 

 As a consequence, the body is unable to protect itself 

 against unavoidable exposures. 



Impairment of tJie lieat-producing capacity is brought 

 about in many ways. Several diseases do this directly, or 

 indirectly, to quite an extent. In health too great care in 

 protecting the body from cold is the most potent cause of 

 its impairment. Staying in rooms heated above a tem- 

 perature of 70 F., wearing clothing unnecessarily heavy, 

 and sleeping under an excess of bed clothes, all diminish 

 the power of the body to produce heat. They accustom 

 it to producing only a small amount, so that it does not 

 receive sufficient of what might be called heat-producing 

 exercise. Lack of physical exercise in the open air, as 

 well as too much time spent in poorly lighted and ven- 

 tilated rooms, tends also to reduce one's ability to produce 

 heat. Moreover, since most of the heat of the body comes 



