96 PHYSIOLOGY FOR NURSES 



tissues and increases their metabolism; i.e., the process 

 by which living cells incorporate substances taken from 

 blood into parts of their own bodies, a sort of cellular 

 digestion or rather building up. Feeding thyroid extract 

 will cause an increase in the output of nitrogen and an 

 increase in the oxidation, or burning up, of fat, That 

 the gland is intimately connected w r ith nutrition is shown 

 by the production of idiocy and arrested growth when it 

 atrophies in the young. The parathyroids are even less 

 understood. Their complete removal causes rapid 

 death. That they are connected with the metabolism of 

 calcium (lime) salts, seems clear. When the thyroid 

 fails to develop in early childhood, a condition called 

 cretinism occurs, in which there is a failure to grow in 

 height or intelligence. In fact the person, though reach- 

 ing adult life, remains an idiotic dwarf. 



Removal of the parathyroids results in a condition of 

 tetany. muscular tremors, which end fatally after pro- 

 ducing convulsive movements especially of the respir- 

 atory muscles. The condition is called liypotJiyroidism 

 and may be relieved by calcium salts. 



Hyperthyroidism is produced by overactivity of the 

 thyroid and is attended by nervousness, muscular wast- 

 ing, weakness and protrusion of the eyeballs, from 

 which symptom the name exoplitlialmic goiter has been 

 derived. 



The active principle of the adrenal bodies is called 

 epinephrine (the trade name of which is adrenalin) 

 which slows the heart ultimately by acting reflexly 

 through the central nervous system, and at the same 

 time causes a great rise in blood pressure by exciting 

 constricton of the arterioles. It also seems to affect car- 



