134 OXIDATION OF TISSUE. 



series of reflex actions, all these processes are kept in harmo- 

 nious relation to each other. It must be borne in mind that 

 increased blood-flow is the consequence, and not the cause, of 

 the increased activity of the tissues. 



The tissues 'of the body are oxidizing all the time. But 

 when they are in vigorous action they oxidize very much 

 more rapidly. 



Insert the bulb of a thermometer into the mouth, and keep 

 it there three or four minutes to find the temperature of the 

 inside of the body. For this it is better to use a clinical 

 thermometer, if one can be obtained. The average tempera- 

 ture of the tissues within the body is about 98.5 F. 



The body may be compared to a stove. Into one we put 

 fuel and produce heat. In the other we get heat from food. 

 But the body is not like the stove in burning the fuel (food) 

 directly. The food is first made into tissues, or " storage 

 compounds " in the tissues. It is as though we were to build 

 a stove entirely of coal, and then start a fire in it. In that 

 case it would produce heat not merely by burning in one 

 place within, but would be burning throughout the whole of 

 its substance. This is the case with the body. 



We have seen that the muscles constitute nearly half of 

 the weight of the body. We know, too, that muscular tissue 

 is more active than most of the tissues. We would now 

 naturally infer, as indeed is the fact, that it is the chief source 

 of the heat produced in our bodies. 



Next to the muscles, in importance as a heat producer, is 

 the liver, which is the largest gland in the body, and, as we 

 shall soon see, one of the most active. The blood, as it leaves 

 the liver by the Hepatic veins, is hotter than anywhere else in 

 the body. 



But it will be better to compare the body to a locomotive, 

 as we produce not only heat, but motion as well. 



