. Nutritional physiology . uence of thisarrangement, constitute short cuts or shunts in the cir-^culation, and are perfused by an exceptionally large quan-tity of blood. No portion of the blood can long escapetheir influence. The urine discharged by the many tubu-lar units of the kidneys is conveyed through the ureters,contractile vessels which lead to the bladder. This, is asaccular organ capable of accommodating much urine whendilated, and of contracting again to nearly complete expul-sion of its contents. Its walls of muscle (the same typefound in the alimentary canal) are obviously under n
. Nutritional physiology . uence of thisarrangement, constitute short cuts or shunts in the cir-^culation, and are perfused by an exceptionally large quan-tity of blood. No portion of the blood can long escapetheir influence. The urine discharged by the many tubu-lar units of the kidneys is conveyed through the ureters,contractile vessels which lead to the bladder. This, is asaccular organ capable of accommodating much urine whendilated, and of contracting again to nearly complete expul-sion of its contents. Its walls of muscle (the same typefound in the alimentary canal) are obviously under ner-vous control and much subject to reflexes. Urine of average composition is a complex solution con-taining some 3 or 4 per cent, of dissolved solids. Theleading substance is urea, the chief nitrogenous waste ofthe system, and the index, according to Folin, of theexogenous metabolism. Its origin has been the duty of the kidney is less to manufactureurea than to select and remove from the blood the urea. r ~-^}. l^iJnt-ys arirl the urinary bladder. Tl,r In,, kidnevsare shown withm an outhne which suggests the borlv cavity Thei?advantageous connections with the chief arterv anrl vein ofthe svstem are indicated. Below is the bladder reached bv the two uretersThese vessels enter the bladder low down and behind-not at where they disappear from the figure REMOVAL OF THE END-PRODUCTS OF METABOLISM 173 originating in the liver and elsewhere. Second in abun-dance among the in*inary constituents we ordinarily findthe mineral salts. The quantity of these depends in alarge measure upon the amoimt in the diet, and as sodiumchlorid is the one taken most freely, so it will generally -bethe principal inorganic compound in the urine. Thechlorids of the mixture are accompanied by phosphates andsulphates. These are not to any extent salts which havebeen eaten, but, like the urea, they represent modifiedfragments of protein molecules. The phosphates comefrom a limite
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Keywords: ., bookcentury1900, bookdecade1910, bookidcu31, booksubjectnutrition
