146 PHYSIOLOGY FOR DENTAL STUDENTS. 



tissue cells. These include substances such as urea, uric acid, 

 creatinin, and ammonia. The non-nitrogenous organic bodies are 

 dextrose, of which 0.1 per cent is present in normal plasma, and a 

 small quantity of fat, About 1 per cent or inorganic salts are 

 found, the chief of which is sodium chloride, which constitutes 

 60 per cent of the ash. Sodium carbonate is found in a little less 

 degree. Besides these two we find small amounts of potassium, 

 sodium and calcium chlorides and phosphates. An important 

 group of substances known as hormones are excreted into the 

 plasma by some of the glands of the body, and affect the meta- 

 bolism of the tissues in a specific manner., Another group of 

 bodies, the antitoxins, complements, and opsonins (see p. 124), 

 are found in the blood. These are concerned in the protection of 

 the body against infective organisms. 



