CHAPTER LXXI 

 THE METABOLISM OF PROTEIN (Cont'd) 



UNDETERMINED NITROGEN AND DETOXICATION 

 COMPOUNDS 



In the present chapter we shall refer briefly to the groups of urinary 

 substances styled undetermined nitrogenous compounds and to the com- 

 pounds that are excreted in the urine as the result of the combination in 

 the body of certain toxic bodies with chemical substances that render 

 them harmless (detoxication compounds). 



Undetermined Nitrogen 



Included under undetermined nitrogen are amino acids, peptides and 

 basic substances. The amount of amino acids and peptides in normal 

 urine is very small but may become considerable in disease, especially 

 of the liver, when leucine and tyrosine may appear. The presence of 

 traces of amino acid and peptone in normal urine is to be expected, 

 for although the actual concentration of amino acids in the blood is 

 never very great, a certain leakage of amino acids must occur into the 

 urine. 



The peptide is sometimes known as oxyproteic acid. It becomes dis- 

 tinctly increased in phosphorus poisoning and in such conditions as are 

 accompanied by excessive protein metabolism. The basic constituents 

 include such substances as trimethylamine, ethylamine, putrescine and 

 cadaverine (page 502), and there are probably many more of a similar 

 nature. Many of these substances are similar to the so-called ptomaines 

 found in meat, etc., and they have been called the ptomaines of urine, 

 from which they can be isolated by rendering the urine alkaline and 

 shaking out with ether. It is probably to the presence of these sub- 

 stances that urine mainly owes its toxic action. 



The Detoxication Compounds 



Certain nocuous substances are produced in the intestine during the 

 digestive process (see page 501), and others may result from the meta- 

 bolic processes in the tissues. To guard against the harmful action of 

 these substances on the organism, they become detoxicated in various 



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