84 



INORGANIC INGREDIENTS. 



Potassium Chlorid. Potassium chlorid (KC1) is found in many 

 of the tissues, especially in the muscles, in blood-corpuscles, and 

 in milk. This salt occurs also in gastric juice, in urine, and in 

 perspiration. Like sodium chlorid, it is neutral in reaction and 

 is soluble in water. 



Source of Potassium Chlorid. Potassium chlorid is contained 

 in both animal and vegetable foods. 



Avenues of Discharge. Potassium chlorid is discharged in 

 mucus, in urine, and in perspiration. 



Calcium Salts Calcium Phosphate, Lime Phosphate, or Phosphate 

 of Lime (Ca 3 (PO 4 ) 2 ). Next to water, calcium phosphate is the 

 most abundant physiologic ingredient of the human body. Its 

 total amount is 2400 grams in a man weighing 65 kilograms. 



The quantity (percentage) of calcium phosphate is as follows : 



Blood 0.03 



Urine 0.07 



Milk , 0.27 



Bone 57.6 



Enamel of teeth 88.5 



The greater part of the calcium phosphate in the body is in the 

 bones. It is estimated that 6.4 per cent, of the body is bone, and 

 in a man weighing 65 kilograms, an average weight, there would 

 therefore be 2400 grams of this salt. Its presence 

 in the fluids of the body is not in noteworthy 

 amount, except in the milk. 



Office of Calcium Phosphate. The principal 

 office of calcium phosphate is to give to the bones 

 their rigidity. During early life this salt is in small 

 amount in the bones, and at this time the bones 

 are soft and yielding. Later, as the phosphate and 

 other inorganic ingredients are deposited in greater 

 amount, these structures become more rigid and 

 better adapted to sustain weight. In old age the 

 inorganic constituents are in excess of the organic, 

 and besides this difference in the proportion of 

 organic and inorganic constituents there is the 

 further difference that the bones of the old are 

 lighter in weight and more porous. This is due 

 to an increase in the size of the medullary canal 

 and the cancel Ions spaces, brought about by absorp- 

 tion ; this is especially marked at the 'articular 

 head. There is also sometimes a fatty change in 

 the bone-tissue. These changes constitute senile atrophy of the 

 bones. At an advanced period of life the bones are easily bro- 

 ken ; while in infancy they bend but do not break, or if they do 

 break, the fracture is not complete, but is similar to that which 

 occurs in a green stick, and is known as the "green-stick fracture" 



FIG. 80. Par- 

 tial or " green - 

 stick " fracture 

 (Stimson). 



