. A text-book of human physiology . nsfusion of blood, abouthalf the quantity transfused remains in the vessels at the end of the first day;while if distilled water is used in transfusion the blood quickly recovers itsnormal constitution (Worm-Miiller, Regeczy). Along with transudation the secretory activity of the glands increases andthis cooperates to diminish the quantity of fluid in the vessels. Particularly isthis true of the mucous membrane of the intestine and of the kidneys. If aNaCl solution bo transfused not too rapidly into a vein, after some time trans-fusion and secretion of urine
. A text-book of human physiology . nsfusion of blood, abouthalf the quantity transfused remains in the vessels at the end of the first day;while if distilled water is used in transfusion the blood quickly recovers itsnormal constitution (Worm-Miiller, Regeczy). Along with transudation the secretory activity of the glands increases andthis cooperates to diminish the quantity of fluid in the vessels. Particularly isthis true of the mucous membrane of the intestine and of the kidneys. If aNaCl solution bo transfused not too rapidly into a vein, after some time trans-fusion and secretion of urine exactly balance each other (Dastre and Loye). Thus by transudation and secretion the quantity of fluid is gradually broughtback to the normal. But this takes place as a rule rather slowly, and other fac-tors meantime must step in to regulate the blood pressure. One such factor isvasodilation, by means of which the resistance in the vessels is lowered (Worm-Miiller). Another is the activity of the heart. If transfusion be performed. Fig. 79.—Blood pressure curve, showing a sudden fall due to stoppage of the heart, as theresult of strong stimulation of the vagus. The time of stimulation indicated by the twovertical lines. | | = ten seconds. slowly enough, the heart is al)le to throw a correspondingly larger quantity ofblood into the vessels and so to preserve the cardiac pressure within safe if the transfusion take place more rapidly, or if the total quantity trans-fused be very large, the heart may drive more blood into the vessels than beforethe transfusion but not enough to prevent stasis of blood in the heart. Finally, 208 CIRCULATION OF THE BLOOD the quantity transfused becomes so great that sooner or later the demands uponthe heart are excessive, and the arterial blood pressure falls in spite of theabnormally large quantity of fluid in the vessels. One sometimes meets withcases where the heart works powerfully enough during the transfusion to over-come the inc
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