24 HUMAN PHYSIOLOGY. 



This is especially true of blood, lymph, and tissue fluids generally. It is 

 essential to physiologic action that all tissue elements should be bathed by 

 an alkaline medium. 



Sodium carbonate, Na 2 CO 3 , is generally found in association with the 

 preceding salt. As it is also an alkaline compound, it assists in giving to the 

 blood and lymph their characteristic alkalinity. In carnivorous animals 

 the sodium phosphate is the more abundant, while in the herbivorous animals 

 the reverse is true. 



Sodium sulphate, Na 2 SO 4 , is present in many of the tissues and fluids, 

 especially the urine. Though introduced in the food, it is also, in all prob- 

 ability, formed in the body from the decomposition and oxidation of the 

 proteins. 



POTASSIUM COMPOUNDS. 



Potassium chlorid, KC1, is met with in association with sodium chlorid 

 in almost all situations in the body. It preponderates, however, in the 

 tissue elements, especially in the muscle tissue, nerve tissue, and red corpuscles. 

 The plasma with which these structures are bathed contains but a very small 

 amount of this salt, but, as previously stated, a relatively large quantity of 

 sodium chlorid. Though introduced to some extent in the food, it is very 

 likely that it is also formed through the decomposition of the sodium chlorid. 



Potassium phosphate, K 2 HPO 4 , is found in association with sodium 

 phosphate in all the fluids and solids. As it has similar chemic properties, 

 its functions are practically the same. 



Potassium carbonate, K 2 CO 3 , is generally found with the preceding salt. 



MAGNESIUM COMPOUNDS. 



Magnesium phosphate, Mg 3 (PO 4 ) 2 , is found in all tissues, in association 

 with calcium phosphate, though in much smaller quantity. 



Magnesium carbonate, MgCO 8 , occurs only in traces in the blood. 



Both of these compounds have functions similar to the calcium compounds, 

 and exist, in all probability, under similar conditions. 



IRON COMPOUNDS. 



Iron is a constituent of the coloring matter of the blood. Traces, however, 

 are also found in lymph, bile, gastric juice, and in the pigment of the eyes, 

 skin, and hair. The amount of iron contained in a body weighing seventy 

 kilograms is about 2.2 gm. It exists under various forms e. g., ferric oxid, 

 ferrous oxid, and in combination with organic compounds. 



Chemic analysis thus shows that the chemic elements into which the 

 compounds may be resolved by an ultimate analysis do not exist in the body 



