138 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



the latter is intact, sinking in this case to perhaps— 11.2 millimeters. 1 What 

 is striking in connection with the "quick -charging'" of the ventricle is that 

 the greatest and longest negative pressure in the auricle coincides, as we should 

 expect, with the earlier part <>f its diastole, and therefore with the systole of 

 the ventricle, when the auricle is cut off from it by the shut valve. 2 By 

 this suction within the auricle the flow from the veins into it probably is 

 heightened, and the store of blood increased which accumulates in the reservoir 

 to await the opening of the valve. The quick-charging mechanism itself is 

 quickly charged. Nor should it be forgotten that the work of the ventricle 

 contributes in some degree to this suction within the auricle. The heart is 

 air-tight in the chest, which is a more or less rigid case. At each ventricular 

 systole the heart pumps some blood out of this case, and shrinks as it does so, 

 thus tending to produce a vacuum; in other words, to increase the amount of 

 negative pressure within the chest, and thus help to expand the swelling- auri- 

 cles. Therefore for the suction which helps to charge the auricles during the 

 systole of the ventricles, that systole itself is partly responsible. 3 



Is the Auricle Emptied by its Systole ? — Authorities differ still as to the 

 extent to which the auricle is emptied by its systole; some holding the scarcely 

 probable view that, during this time, its contents are all, or nearly all, trans- 

 ferred to the ventricle; 4 and others taking the widely different view that the 

 auricle actually continues to receive blood during its systole, which latter simply 

 increases the discharge into the ventricle. According to this latter opinion the 

 flow from the great veins into the auricle is absolutely unbroken. 5 All are 

 agreed, however, that the auricular appendix is the most completely emptied 

 portion of the chamber. 



Are the Venous Openings into the Auricle closed during- its Systole ? 

 If not, does Blood then regurgitate, or enter? — As to these questions dif- 

 ferences of opinion are possible, because at the openings of the veins into the 

 auricle no valves exist which are effective in the adult, except at the mouth of 

 the coronary sinus. It is therefore a question, what happens at the mouths of 

 the veins during the auricular systole. These mouths are surrounded by rings 

 composed of the muscular fibres of the auricular wall ; and for some distance 

 from the heart the walls of some of the great veins are rich in circular fibres 

 of muscle. We have seen already (p. 115) that a rhythmic contraction of the 

 venae cavic and pulmonary vein- occurs just before the systole of the auricles 

 and musl accelerate the flow into the latter. Their swiftly following systole is' 

 known to begin at the mouths of the great veins and from these to spread over 

 the rest of each auricle. It is evident at once that the circular fibres must 



1 < roltz and < ranle : op. cit., p. 109. 



2 von Frey uud Krehl: i>/>. cit., p. 5.",; \\ r . T. Porter: op. cit., p. 523. 



' A. Mosso: Die Diagnostik des Pulses, etc. Zweiter Theil : Ueber den negativen Puis, 

 S. 42. 



1 M. Foster: .1 Text-book of Physiology, New York, 1896, p. 182. 



Skoda: " I'eher die Function der Vorkammern des Herzens," Sitzungsberichfe der maihem.- 

 rmturw. Classe der kai*. Akminnif 'l<r Wixsnixchnften in Wien, 1852, Bd. ix. S. 788. L. Her- 

 mann : Lehrbuch der Physiologie, 1900, S. 66. 



