416 
DIGESTIVE ORGANS AND FOOD 
Because alcohol contains no nitrogen, it cannot be used as 
a food to build up tissue. 
USES OF NUTRIENTS IN THE BODY 
Protein Forms tissue 
e.g., white (albumen) of eggs, 
curd, casein (ka'se-In) of milk, lean 
meat, gluten of wheat, etc. 
Fats Are stored as fat 
e.g., fat of meat, butter, olive 
oil, oils of corn and wheat, etc. 
Carbohydrates 
e.g., sugar, starch, etc. 
Mineral matter (ash) 
e.g., phosphates of lime, 
potash, soda, etc. 
Vitamines found in 
milk, eggs, meat, fruit, 
vegetables, and whole grains 
Are transformed into fat 
All serve as 
fuel to yield 
energy in the 
form of heat 
and muscular 
power. 
Shares in forming bone, 
assists in digestion, etc. 
Help keep people 
well and promote the 
growth of children. 
Heat is a form of energy and one of the reasons for taking 
food is to keep up the supply of this energy. The more work 
a person does the more energy he uses, but even a resting 
body uses some energy, for the heart beats and the muscles 
of the chest move. The amount of this form of energy a 
person uses is measured by a unit of heat named the calorie 
(kal'b-ri). A calorie represents the amount of heat required 
to raise the temperature of a pint of water about four 
degrees Fahrenheit. A man in rising from a chair, walking 
eight feet, and returning to the chair uses about one calorie 
of energy. 
The term calorie just defined is now used throughout the 
civilized world as the common unit of measurement for food 
energy. Through the studies of experts it has been deter¬ 
mined how many calories are necessary to keep the human 
body from starvation, how many more must be added if 
the body is to do light physical work, and how many more 
if heavy manual labor is done. By knowing the total number 
