ENDOCRINE GLANDS AND THEIR FUNCTIONS 677 



The influence of other hormones of the body is noted in the repro- 

 ductive and sexual processes. The effect of the pituitary has already 

 been mentioned. The thyroid secretion probably plays a role, not 

 clearly understood, in the female reproductive processes, since the 

 thyroid always enlarges at puberty and during pregnancy. Another 

 hormone is thought by some investigators to be formed in the pla- 

 centa during the development of an embryo. The interrelationships 

 of these hormones are involved, and doubt exists in some cases as to 

 their exact functions. 



The Pancreas 



This is one of the organs serving a dual purpose in the body; it 

 secretes from a group of its cells, called the islands of Langerhans, a 

 hormone designated as insulin. Experiments have shown the action 

 of insulin to be concerned with the metabolism of carbohydrates 

 and fats. Its presence facilitates the combustion of carbohydrates, 

 regulates the rate of sugar production by the liver, and promotes 

 the storage of sugar as glycogen in the muscles. It therefore de- 

 creases the amount of sugar in the blood. 



Extracts of insulin are obtained from the pancreas of animals and 

 are used commercially for the treatment of the condition kno^vn as 

 diabetes. This disorder is due to a disturbance of the metabolism 

 of sugars, provoked by a deficiency of insulin. The blood contains 

 too great a percentage of sugar, but this is not turned into needed 

 energy, and much water is excreted by the kidneys in order to elimi- 

 nate the excess sugar. The patient suffers, therefore, from fatigue, 

 excessive hunger, and thirst. The injection of insulin subcutane- 

 ously assists in regulating the condition by restoring the power to 

 transform glucose into glycogen in the muscles. The patient re- 

 gains strength and weight as a result, but the treatment does not 

 perfect a complete cure and additional insulin must be injected at 

 intervals to maintain normal health. Overdoses of insulin result in 

 very serious disturbances, which may be relieved by ingestion of 

 glucose. 



Among the functions of the hormone, adrenalin, is the accelera- 

 tion of the production of glucose in the blood; it is apparent, there- 

 fore, that the hormones, insulin and adrenalin, are antagonistic in 

 their effect on sugar metabolism, and an upset of the normal pro- 

 duction of these secretions results in metabolic disturbances. 



