A reference handbook of the medical sciences, embracing the entire range of scientific and practical medicine and allied science . d so creates a negative pressure. A more efficientcause is probably found in the peculiar conditionssurroundiiig the coronary circulation. The filling of REFEREXCE HANDBOOK OF THE MEDICAL SCIEXCES Blood, Circulation of the blood-vessels in the walls of the heart shouldopen up its cavities much in the same way that adouble-walled bag is distended by filling in the spacebetween the two layers. Briickes theory of theSelbststeuerung des Herzens was, in fact, basedon th
A reference handbook of the medical sciences, embracing the entire range of scientific and practical medicine and allied science . d so creates a negative pressure. A more efficientcause is probably found in the peculiar conditionssurroundiiig the coronary circulation. The filling of REFEREXCE HANDBOOK OF THE MEDICAL SCIEXCES Blood, Circulation of the blood-vessels in the walls of the heart shouldopen up its cavities much in the same way that adouble-walled bag is distended by filling in the spacebetween the two layers. Briickes theory of theSelbststeuerung des Herzens was, in fact, basedon this sort of mechanism. It assumed that thesemilunar valves were thrown back during systolefar enough to prevent the entrance of blood into thecoronary arteries, whose distention at that timewould oppose the systole; but when at the oiLset ofdiastole, the coronaries are opened and the bloodenters under strong pressure from the aorta, thediastolic expansion would be materially theory has since been shown to be a curiousmixture of truth and error. Martin and Sedgwickdemonstrated that the pulse in the coronaries was. Fig. 734.—Showing Cur\-es of Pressure (A) and Velocity (B) inthe Coronary Artery of the Horse. (Chauveau and Rebatel.) synchronous with that in other systemic arteries;therefore Briicke was wrong so far as the mechanismby which the systolic dilatation of the coronaryvessels is prevented is concerned. The semilunarvalves do not close the orifices of these of the velocity of the blood flow in thecoronary arteries by Chauveau and Rebatel haveshown, on the other hand, that he was right as to thefacts. Their curves (see Fig. 734) show that thetension and rate of flow both increase in the coronaryartery at the beginning of systole (o); bloodstreams into it at this time. Then a second rise ofpressure is obser\-ed during which, however, thevelocity curve drops below the abscissa (b). This isthe moment when the contraction of the ventri
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