391 



IHE MAINTENANCE OF THE INDIVIDUAL 



synthesized. Its effect is very interesting. It is known that small 

 amounts of adrenin are being continuously secreted and passed into 

 the blood stream to have an effect upon the involuntary muscles 

 of the body. In cases of emotional excitement there is an increased 

 secretion of adrenin, in consequence of which there results a more 

 rapid heartbeat, together with an increase of blood flow and of the 

 glucose output from the liver. This in turn brings about greater 

 efficiency of the muscles and so increases the capacity for work. If 

 this portion of the gland is not operating normally such symptoms 



as muscular fatigue, cold hands 



and feet, sensitiveness to cold, 

 mental indecision, and sometimes 

 collapse and heart failure ensue. 

 Adrenin is efficacious in reliev- 

 ing severe bronchial spasms dur- 

 ing attacks of asthma and it has 

 also been successfully used to 

 mitigate the distress caused by 

 hives and by hay fever. 



.thyroid cartilage 



pry amid lobe 

 of-^VnyroicL 



-P (xra-thyro i cC 



-isLhrotcS 

 -left lobe-^of 

 thyroid. ^lancC 

 -pa.rat by ro i cC 



-trcLCh 



ecc 



viewed, from |i'«nt/ 



Diagram showing the location and 

 relationship of the thyroid and para- 

 thyroid glands. 



Thyroid 



Some sort of thyroid gland is 

 present in all of the vertebrates. 

 In every instance it arises as an 

 outgrowth from the pharyngeal 

 region and is, therefore, a deriva- 

 tive of the digestive tract. In man the thyroid is definitely bilobed 

 and in cases of goiter may be considerably enlarged. 



The secretion of the thyroid gland, thyroxin (C11II10O3NI3), was first 

 isolated by Kendall in 1914 and later improved isolation methods gave 

 Ci5Hii04NI,i (Harrington, 1926). Under normal conditions but little 

 of this substance is secreted at a time, in evidence of which is the fact 

 that three and one-half tons of fresh thyroid glands are necessary to 

 produce 36 grams of crystalline thyroxin. This substance regulates 

 the rate of the transformation of energy in the body, thus controlling 

 the metabolic rate. Its potency is almost uncanny, as is evidenced 

 by the fact that one milligram of thyroxin produces a two per cent 

 increase in the total oxidation of a resting adult body. 



One concept of the rate of metabolism in the human body may be 

 secured through the basal metabolism test, a device to measure the 



