148 ANATOMY FOR NURSES [Chap. IX 



Serum-albumin belongs to the group of albumins of which white 

 of egg is a member and holds the first place in regard to nutrition. 

 It represents the protein portion of our food supply and the 

 greater part of the material necessary for the daily nourishment 

 and renovation of the tissues. In this process it undergoes a 

 variety of transformations, by which it is converted into the struc- 

 tural characteristics of the tissues which it supplies. 



Para-globulin ^ belongs to the class of globulins. The origin 

 and function are undecided. It may be a source of nitrogenous 

 food, and assists in coagulation of the blood. 



The serum-albumin and para-globulin occur in about equal quan- 

 tities. 



Fibrinogen belongs to the class of globulins, and is the sub- 

 stance which produces the fibrin of coagulated blood. It is very 

 difficult to obtain in the fluid condition, owing to the rapidity with 

 which it solidifies when blood is withdrawn from the circulation. 

 Though it is a most important element in the blood, it occurs in 

 very small quantities. 



Extractives. — Extractives are substances other than proteins 

 that may be extracted from dried blood by special methods. 



Sugar in the form of glucose is present under normal condi- 

 tions in the amount of 0.1 to 0.2 per cent. A temporary in- 

 crease in the amount of sugar may follow the ingestion of a large 

 quantity. 



Fat is found in the plasma in about the same proportion as 

 sugar. It is much more subject to variation, rising notably 

 after a meal in which there was much fat. 



Waste products found in the plasma represent the end products 

 resulting from the oxidation of our food. Due to the efficiency of 

 the kidneys and supplementary organs of excretion they occur 

 in very small quantities. 



Salts. — The salts found in the blood amount to about one per cent 

 of the total solids. They are derived from the food and from the 

 chemical reactions going on in the body. The most abundant is 

 sodium chloride. 



Gases. — OxA'gen, nitrogen, and carbon dioxide gas are found 

 in the blood. Carbon dioxide is the result of oxidation in the 



' Albumins and globulins give the same general tests ; they are both coagulated 

 by heat, and the chief difference is in their solubilities. 



