The Endocrine System 235 



THE ADRENAL CORTEX 



The absolute importance of the adrenal cortex has long been known, 

 and recent work has served to emphasize the varied, vital functions 

 controlled by this gland. Embryologically, its origin is from the same 

 tissues as that of most of the visceral organs. 



The Function of the Adrenal Cortex. — The cortical extract, 

 cortin, is absolutely essential for life. The dififerent components of 

 cortin appear to afifect several vital functions whose specific effects 

 are very difficult to assess. Briefly, these functions can be summarized 

 as follows: (1) the control of the levels of sodium and potassium in 

 the blood, (2) considerable control over carbohydrate and protein 

 metabolism, and (3) some influence over kidney function. Clearly any 

 understanding of these functions must result only from the abnormal 

 situation attained when the gland is extirpated. 



Under such circumstances, it is shown that the death of the ex- 

 perimental animals is due to an imbalance of the water and the sodium 

 and potassium. In the normal animal, sodium is more concentrated 

 in the extracellular fluids, while potassium is most abundant in the 

 intracellular fluids. With cortical insufficiency, these ions are disturbed 

 in their arrangement on the cell membranes and the osmotic equilib- 

 rium is upset. Due to this, water moves from the extracellular spaces 

 into the cells, resulting in concentration of the blood, a fall in blood 

 pressure, and finally death from dehydration. The level of sodium in 

 the blood is lowered due to its being eliminated by the kidney, and the 

 concentration of potassium is raised due to kidney retention. The ad- 

 ministration of cortical extracts will relieve this situation by causing 

 the fluids which were held within the cells to be transferred to the 

 extracellular spaces and into the blood. 



In the adrenalectomized animal, the absorption, formation, storage, 

 and utilization of carbohydrates are interefered with. Such an animal 

 is unable to form carbohydrates from noncarbohydrate sources such 

 as protein. Instead, the animal excretes nitrogen and forms new carbo- 

 hydrates at the expense of tissue protein. This possibly accounts for 

 the fact that muscular weakness occurs in adrenalectomized animals 

 due to this impaired carbohydrate metabolism. 



The failure of the kidneys to function properly during cortical in- 

 sufficiency presumably is due to the excessive loss of sodium chloride, 

 the retention of potassium, and the reduced elimination of some waste 

 products. These latter accumulate in the blood. Possibly further dis- 



