154 ANATOMY AND PHYSIOLOGY 



in bones and teeth especially, as lime salts; muscles, nerves, and 

 blood, as potassium salts; all tissues, as sodium salts; red blood cells, 

 as iron. 



In the food : 



1. Proteins exist in meats, as myosin and albumin; eggs, as 

 albumin in the white, lecithin in the yolk; grains, as gluten; 

 vegetables: peas, beans, corn, etc., as vegetable albumin. 



2. Carbohydrates (sugars and starches) exist in fruits, as 

 dextrose and levulose; milk, as lactose; sugar cane, beets, etc., as 

 cane sugar and saccharose; vegetables: peas, beans, potatoes, etc., 

 as starch. 



3. Fats exist in milk, as an emulsion; corn, oats and other 

 grains; eggs (the yolk) and all animal foods in varying quantities. 



4. Mineral salts exist in all foods (but must be added in bulk) ; 

 water, the most important; vegetable, grains and protein foods, as 

 phosphate of calcium; meats and all animal food, as iron; all foods, 

 as sodium chloride or common salt. 



Proteins must be supplied to all tissues; they are the tissue 

 builders. 



Carbohydrates (or sugars and starches) are utilized by liver 

 and muscle, and are sources of heat and muscle energy. 



Fats are needed for the marrow of bones, as protective cover- 

 ings, and to fill in spaces between organs; also to preserve body 

 heat as well as to produce it. 



Mineral salts are necessary to life. 



Water constitutes nearly three-fourths of the body weight, 

 and is universally present, even in the hardest tissues, as the 

 enamel of teeth. Its most important uses are: i. To hold in 

 solution the nutritive principles of the food, that they may be 

 absorbed. 2. To sweep away waste matters to organs which 

 can secrete them. 3. To aid in regulating the temperature of 

 the body. 



Sodium chloride stands next in importance to water. It is 

 necessary to the normal activities of the tissues. It contributes 

 to the formation of hydrochloric acid for gastric juice. 



Phosphate of calcium is needed by bones and teeth; it is the 

 most abundant salt in the body, next to water. 



Calcium is indispensable to normal blood. 



Iron is a necessary element of red blood cells, in hemoglobin. 



