SECRETIONS 



101 



muscular emergency. This is due to its effect upon the smooth 

 muscle in the walls of the blood vessels. The cortex secretion 

 is concerned with the regulation of 

 the secondary sexual characteristics, 

 notably the growth of hair. 



Like the adrenals, the pituitary 

 gland, located ventral to the dien- 

 cephalon, is composed of two parts, 

 the anterior lobe being formed from 

 the hypophysis, and the posterior lobe 

 from the infundibulum (c/. p. 65). 

 The secretion of the anterior lobe, 

 known as tethelin, is active in regulating 

 growth, particularly that of the long 

 bones. Abundant over-secretion results 

 in gigantism in youth and acromegaly 

 when it occurs in adults (Fig. 58). The 

 secretion of the posterior lobe is 

 called pituitrin, and has a marked 

 effect upon smooth muscle fibers, 

 similar to that of adrenalin. 



The pancreas is composed of cells 

 differing in their functions. The pan- 

 creatic juice, which has already been 

 mentioned, is passed into the small 

 intestine by way of the pancreatic duct 

 and is important in digestion. In ad- 

 dition to the cells elaborating this 

 secretion, there are, scattered through- 

 out the pancreas, groups of cells, known 

 as the islands of Langerhans, producing 

 the endocrine insulin which is discharged 

 into the blood (Fig. 59). Insulin has 

 the important function of regulating the 

 storage of sugar b}' the liver cells. If 

 this secretion is absent, sugar is pres- 

 ent in excessive amounts in the blood 

 and conditions of glycosuria and diabetes result. Injections of 

 insulin have been effective in correcting diabetic symptoms, 

 and its isolation and the technique of its use constitute a recent 



Fig. 58. — Individual in 

 which gigantism has re- 

 sulted from over-secretion 

 by the pituitary gland. 



Note the narrow chest, length 

 of arms and legs, and large size 

 of hands and feet. Height, 8 ft., 

 3 in. (From Gushing, "The 

 Pituitary Body and its Dis- 

 orders," copyright, 1912, by 

 Lippincott and Co., reprinted 

 by permission.) 



