CHEMICAL REGULATORS 



39- 



oxygen-carbon dioxide Ixilance, which determines the amount of 

 energy required to keep th(> body aHve, maintain its temjierature, 

 muscle tone, rate of breathing, and heartbeat. It has been con- 

 ckisively shown by a sufficient number of studies that a comparison 

 of people who have been placed under similar conditions may be 

 made, and it is now pos- 

 sible, as a result of these 

 tests, to gain a highly 

 accurate idea of the meta- 

 bolic rate of different 

 people, and so to detect 

 an over- or under-activity 

 of the thyroid gland. 

 Both conditions are ab- 

 normal, indicating rather 

 serious metabolic malad- 

 justments. 



If the thyroid is over- 

 active, a person so affected 

 usually has a high basal 

 metabolic rate. Such a 

 person finds his combus- 

 tion rate speeded up and 

 is a heavy eater, but at 

 the same time that he 

 burns his food products 

 rapidly, he gradually be- 

 comes weaker and weaker. Evidence of a high metabolic rate shows 

 further in nervousness and irritability. The individual is also char- 

 acterized by protruding eyeballs, an increased and more irregular 

 heartbeat, as well as a higher temperature, insomnia, and general 

 nervousness, which in advanced cases may seriously undermine both 

 the mind and health. This general picture of overactivity is typically 

 associated with the variety of goit(T known as exophthalmic goiter. 



Another type of goiter, "common goiter," is frequently encoun- 

 tered in regions wdiere there is a material lack of iodine in the water and 

 soil. In such cases there is an insufficient supply of thyroxin secreted, 

 which is sometimes due to a decrease of iodine in the chemical com- 

 position of the thyroxin molecule. Nature apparently endeavors to 

 compensate for this by increasing the size of the gland with rather 



Xew York AcfuUmy of Medicine 



An example of a goiter. What type is it .3 

 What caused it !> 



