PANCREATIC DIGESTION 



67 



Normal 



a-amido-caproic 



acid. 



/CH3 

 CH2 

 CH, 



CH.NH., 

 ICOOH. 



Iso- butyl 



a-amido- 



acetie acid 



/CH3 CH3 



\/ 

 CH 

 CH2 



CH.NH2 

 COOH. 



Tyrosine is a little more complicated, as it is not only an amido-acid, 

 but also contains an aromatic radicle. Propionic acid has the 

 formula C2H5.COOH ; amido-propionic acid is C2H4.NH2.COOH, 

 nd is called alanine. If another H in this is replaced by oxjrphenyl 

 C^H,.OH), we get C.H3.NH2.C6H4OH.COOH, which is oxyphenyl- 

 amido-propionic acid, or tyrosine. Figs. 22 and 23 represent the 

 ci ystalhne forms of leucine and tyrosine. 



EXTIRPATION OF THE PANCREAS 



Complete removal of the pancreas in animals and diseases of the 

 pancreas in man produce a condition of diabetes, in addition to the 

 loss of pancreatic action in the intestines. Grafting the pancreas 

 fi-om another animal into the abdomen of the animal from which the 

 pancreas has been removed reheves the diabetic condition. 



How the pancreas acts otherwise than in producing the pancreatic 

 juice is not known. It must, however, have other functions related 

 to the general metabolic phenomena of the body, which are disturbed 

 by removal or disease of the gland. This is an illustration of a 

 universal truth — viz. that each part of the body does not merely do 

 its own special work, but is concei'ned in the great cycle of changes 

 which is called general metaboHsm. Interference with any organ 

 upsets not only its specific function, but causes disturbances through 

 the body generally. The interdependence of the circulatory and 

 respiratory systems is a well-known instance. Eemoval of the 

 thyi'oid gland upsets the whole body, producing widespread changes 

 known as myxoedema. Eemoval of the testis produces not only a 

 loss of the spermatic secretion, but changes the whole growth and 

 appearance of the animal. Eemoval of the greater part of the 

 kidneys produces rapid wasting and the breaking down of the tissues 

 '^ form an increased quantity of urea. The precise way in which. 

 aese glands are related to the general body processes is, however, a 

 subject of which we know as yet very Mttle. The theory at present 

 most in favour is that certain glands produce an internal secretion, 

 which leaves the gland via the lymph, and is then distributed to 

 minister to parts elsewhere. Eemoval of such glands as the thyroid 



f2 



