12 



APPLIED PHYSIOLOGY 



ashes are the mineral parts of the meat. This is what 

 takes place in every fire. We call it oxidation. If the 

 fire is under the boiler of an engine, the heat is used in 

 changing the water to steam. The steam can then be 

 made to do work. 



11. Oxidation within the body. Besides meat and other 

 kinds of food, air is also taken inside of our bodies. Car- 

 bonic acid gas and water are given off in the breath, our 



bodies are warmed, and 

 they perform work, as a 

 steam engine does. The 

 body is really an engine 

 directed by the mind. The 

 lungs are the boilers, while 

 the nose is the draft where 

 the oxygen enters and the 

 carbonic acid gas and 

 water pass out. Both the 

 food and the cells of the 

 body are oxidized. By the 

 oxidation the same heat is 

 produced as though the food were burned outside the body, 

 but it occurs so slowly that no flame is produced. Most 

 of the heat simply warms the body. The muscles and 

 brain form the engine which changes the rest of the heat 

 to work. All the power of a man's body is derived from 

 the heat of oxidation. Running, speaking, and thinking 

 are different kinds of work, and depend upon the heat of 

 oxidation for power. v 



12. Use of food. The greater part of the fuel for oxi- 

 dation is supplied by the food before it reaches the cells 

 of the body. The cells themselves are also slowly oxidized. 

 In course of time their substance is completely burned up, 



Diagram of burning or oxidation in a 

 stove. 



