CHAPTER IV 



FATS, PHOSPHATIDS AND ALLIED SUBSTANCES 



Distribution and Importance. The fats are widely distrib- 

 uted in nature, in both plants and animals. In the former they 

 are found in seeds such as cotton seed, the castor bean, etc., in 

 fruits, such as olives, in nuts and also in the leaves and roots of 

 some plants. In animals they are found in most tissues and 

 fluids. The amounts in the tissues vary considerably. The ac- 

 tive living protoplasm contains only about 1-10%, whereas mar- 

 row, fatty tissue, etc., may contain considerably over 90%. The 

 fats are of importance as fuels for the body. They are laid 

 away in large deposits which also serve the purpose of insulat- 

 ing the body by forming a blanket layer which aids in the con- 

 servation of heat. There is a layer of subcutaneous fat, and 

 there are also large deposits around the abdominal viscera. 

 Considerable quantities are found in the intramuscular con- 

 nective tissue. 



Composition and Structure. The fats are made up of car- 

 bon, hydrogen and oxygen. The oxygen is present in much 

 smaller per cent than in the carbohydrates. The constituent 

 parts of the fats are the triatomic alcohol glycerine or occa- 

 sionally some other alcohol, and organic acids, either of the fatty 

 acid or a similar series. It is of interest that the acids making 

 up the body fats have even numbers of carbon atoms in their 

 molecules. The following list gives the names and formulas of 

 some of the important acids: 



Butyric CH,CH 2 CH 2 COOH (C 4 H 8 2 ) 



Caproic CH 3 CH 2 CH 2 CH 2 CH 2 COOH (C 6 H 12 2 ) 



Caprylic CH 3 (CH 2 ) 6 COOH (C 8 H 16 2 ) 



Capric CH,(CH 2 ) 8 COOH (C 10 H 20 2 ) 



Palmitic CH 3 ( CH ) 14 COOH ( C 10 H 32 O 2 ) 



Stearic CH 3 (CHJ 16 COOH (C 18 H 36 2 ) 



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