BALANCE OF CALCIUM 



247 



§ 5.412 



rats contain more calcium and phosphate than do the controls, 

 the excess being in the muscles rather than in the bones. Excess 

 parathyroid secretion, or injection, usually results in maintaining 

 high serum calcium and a high level of Ca excretion at the expense 

 of the calcification of bone (Bartter, 1954). •^^GlIC/^/" 



Fig. 5-27. Changes in the concentrations of calcium and inorganic 

 phosphates in the blood of the dog, Cams. They change little 

 prior to extirpation of the parathyroid glands on day 20, when 

 phosphates rise and calcium drops sufficiently to induce tetany. 

 Injection of parathormone raises the calcium value sufficiently 

 to prevent the return of tetany for about a week ; but tetany occurs 

 whenever the calcium level falls below about 7 mg/100 ml in the 

 blood (from Weaver and Reed in Win ton and Bayliss, 1955). 



5.412 Decrease of calcium in the blood 



Crustacea. The weight of evidence favours the assumption that 

 the GANGLiONic-X-ORGAN /sinus GLAND complex is the source of a 

 hormone v^hich restrains the rate of calcium accumulation in the 

 blood; it may be the same hormone as MIH that restrains the 



