ENERGY SUPPLY OF THE BODY 



I8 7 



2. Heat Power. The body keeps itself warm and is 

 able to communicate warmth to its surroundings. 



3. Nervous Power. Through the nervous system the 

 body exercises the power of control over its different parts. 



As motion, heat, and nervous power the body uses most 

 of its energy. 



The Source of Bodily Energy. As already indicated, 

 the energy of the body is supplied through the food and 

 the oxygen. These contain energy in the potential form, 

 which becomes kinetic (active) through their uniting with 

 each other in the body. Somewhat as the power of the 

 steam engine is derived from the combustion of fuel in 

 the furnaces, the energy of the body is supplied through 

 the oxidations at the cells. How the food and oxygen 

 come to possess energy is seen by a study of the general 

 methods by which energy is-stored up and used. 



Simple Methods of Storing Energy. Energy is stored 

 by converting the kinetic 

 into the potential form. 

 Two of the simplest ways 

 of doing this are the fol- 

 lowing: 



i. Storing of Energy 

 through Gravity. On ac- 

 count of the attraction be- 

 tween the earth and all 

 bodies upon the earth, the 

 mere lifting of a weight puts 

 it in a position where gravity 

 can cause it to move (Fig. 

 81). As a consequence the 



raising of bodies above the earths surface is a means of 

 storing energy the energy remaining stored until the 



FIG. 81. Simple device for stor- 

 ing energy through gravity. 



