1 8 HUMAN PHYSIOLOGY CHAP. 



body needs foods to furnish the heat which keeps us 

 warm and to yield the energy which enables us to work. 

 The chief heat-producing and energy-yielding food stuffs 

 are called carbohydrates (starches and sugars] and fats. 



The proteids, carbohydrates, and fats would be of no 

 value to the cells without oxygen. It is only when 

 coal and oxygen are made to combine that heat is pro- 

 duced in a furnace, and likewise no burning or oxidation 

 could take place in the cells without an abundant supply 

 of oxygen. 



The solid food stuffs could not get into the blood nor 

 to the cells if they were not dissolved in water and car- 

 ried along by water, which makes up a large part of the 

 blood. Salt is another class of necessary food stuffs. 



TABLE OF FOOD STUFFS 



1 . Proteids, the building foods. 



2. Carbohydrates 1 



P t \ the force and heat producing foods. 



4. Water 1 



5. Salts \ important aids in both. 



6. Oxygen 



21. Proteids. They form the only class of foods that 

 contain all the elements necessary to cause growth arid to 

 repair cells. For this reason proteids are absolutely 

 necessary to maintain life. Eggs, lean meats, cheese, 

 beans, peas, lentils, and milk are among the common 

 foods that belong to this class. Most of the cereals, as 

 wheat, barley, oats, and corn, contain considerable pro- 

 teid. This is the kind of food that makes muscle and 

 other tissues. We would starve without proteids. 



