488 THE HUMAN BODY 



protections against excessive cooling. Man needs to supplement 

 them in cold climates by the use of clothing, fuel, and exercise. 



Local Temperatures. Although, by the means above described, 

 a wonderfully uniform bodily temperature is maintained, and by 

 the circulating blood all parts are kept at nearly the same warmth, 

 variations in both respects do occur. The arrangements for equal- 

 ization are not by any means fully efficient. External parts, as the 

 skin, the lungs (which are really external in the sense of being in 

 contact with the air), the mouth, and the nose chambers, are al- 

 ways cooler than internal ; and even all parts of the skin have not 

 the same temperature, such hollows as the armpit being warmer 

 than more exposed regions. On the other hand, a secreting gland 

 or a working muscle becomes warmer, for the time, than the rest 

 of the Body, because more heat is liberated in it than is carried off 

 by the blood flowing through. In such organs the venous blood 

 leaving is warmer than the arterial coming to them; while the 

 reverse is the case with parts, like the skin, in which the blood is 

 cooled. An organ colder than the blood is of course warmed by an 

 increase in its circulation, as seen in the local rise of temperature 

 in the skin of the face in blushing. 



Fever. The condition of fever or pyrexia, as an abnormally high 

 temperature is named, could conceivably be brought about by 

 increased heat production, decreased heat loss, or both; or by a 

 greater increase of production than of loss. Direct experiments 

 on animals prove that there is always increased production of 

 heat, in febrile diseases. This is shown by the fact that the animal 

 uses more oxygen and gives off more carbon dioxid in a given time 

 than when in health. It also usually gives off more heat, but not 

 enough to compensate for the increase of oxidative processes going 

 on in its body, and so its temperature rises. The regulating mech- 

 anism which in health keeps heat production and heat dissipa- 

 tion proportionate is out of gear. The increased heat production 

 during fever is usually attributed to stimulation of the oxidative 

 processes of the Body by toxins in the blood, but the mechanism 

 of their action is not known. It has been suggested that fever is a 

 protective reaction in that it raises the body temperature above 

 that which is most favorable to the growth of the invading organ- 

 isms, while at the same time favoring the development of the re- 

 sisting mechanism of the Body itself. 



