448 



ORGAN SYSTEMS OF MAN 



Fig. 16-36. A case of acromegaly. Note particularly the 

 protruding lower jaw, massive brows, and the en- 

 larged hands. 



terior lobe of the pituitary always reveals 

 a greatly enlarged organ, sometimes reach- 

 ing the size of a hen's egg. On the other 

 hand, when the gland fails to produce the 

 proper amount of hormone a midget results 

 (Fig. 16-35). It is to be noted that giants 

 or midgets are produced only when the 

 gland either overfunctions or underfunc- 

 tions in the young child. 



Both dwarfism and giantism can be pro- 

 duced in animals simply by removing the 

 pituitary in the first case and supplement- 

 ing with grafted pituitaries or extracts in 

 the second. Dogs can be forced into giants 

 by placing glandular material under the 

 skin or injecting purified extracts of the 

 anterior lobe of the pituitary. If the gland 

 is removed in a pup, growth takes place 

 very slowly, if at all, and the dog becomes 

 a midget. In human beings with overactive 

 anterior lobes, removal is the only remedy 

 known so far. In pituitary midgets injec- 

 tions of refined extracts is beneficial. 



If increased activity occurs after maturity 

 has been reached, as it occasionally does 

 when a tumor forms on the pituitary, the 

 person does not then become a giant, al- 

 though deep-seated changes do occur. 

 Since the body has already ceased growing 

 the effort to produce a giant by further in- 

 crease in size is restricted to the regions of 

 the joints and the face. Consequently, a 

 person so afflicted becomes barrel-chested, 

 beetle-browed, and long-jawed, while the 

 feet and hands grow very large (Fig. 

 16-36). Such a condition is spoken of as 

 acromegaly. 



Thyrotrophin effects. Very little is known 

 about the relationship between the pitui- 

 tary and the thyroid except that thyroxin 

 will not supplant hormones from the pitui- 

 tary in correcting pituitary deficiency. A 

 hormone from the pituitary probably initi- 

 ates or stimulates the thyroid to produce 

 varying amounts of thyroxin, 



Corticotrophin effects. The adrenal cortex 

 and its production of cortisone are directly 

 under the control of a specific hormone 



