Physiology and biochemistry in modern medicine . been found that the amino-acid content increases until from 60 to80 mg. per cent of amino acid has accumulated. Beyond this point,however, the muscles do not seem to be able to take up any more aminoacid. The capacity of the intestinal organs, however, is more elastic; This is a convenient way of stating per 100 of blood. 608 METABOLISM for example, the amino nitrogen of the liver has been observed to becomeincreased to 125 or 150 mg. per cent of the original amount. Althoughthis absorption of amino acids by the tissues is extremely rapid,
Physiology and biochemistry in modern medicine . been found that the amino-acid content increases until from 60 to80 mg. per cent of amino acid has accumulated. Beyond this point,however, the muscles do not seem to be able to take up any more aminoacid. The capacity of the intestinal organs, however, is more elastic; This is a convenient way of stating per 100 of blood. 608 METABOLISM for example, the amino nitrogen of the liver has been observed to becomeincreased to 125 or 150 mg. per cent of the original amount. Althoughthis absorption of amino acids by the tissues is extremely rapid, it neverproceeds to such a point that the blood becomes entirely free of after many days starvation the blood contains its normal quotaof from 3 to 10 mg. per 100 gm. of moist tissue (Fig. 188). This indicatesthat a certain equilibrium must become established between the amino-acidcontent of the blood and that of the tissues, the concentration in the tissuesbeing approximately from five to ten times greater than in the blood. 150 100. 1 3 HoursFig. 187.—Curves showing the amount of amino nitrogen taken up by different tissues afterthe cutaneous injection of amino acids. The lowermost curve shows the urea concentration of theblood. (From D. D. Van Slyke.) The absorbed amino acids are very loosely combined with the tissues,for they can be extracted by such feeble reagents as water or dilute al-cohol. Their presence can not, however, be merely due to diffusion;for if it were, the concentration could not become greater in the tis-sues than in the blood. The further fate of the amino acids is difficultto follow. We know that they do not remain in the body for a long time,because most of the protein nitrogen in the food is excreted as ureawithin twenty-four hours after ingestion; and when single amino acidsare fed, they quickly reappear in the urine as urea. THi: OF 609 The tissues can therefore be only a stopping-place for the aminoacids. When the l
Size: 1321px × 1892px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpubli, booksubjectphysiology
