A text-book of physiology for medical students and physicians . number ofobservers have recorded the time upon a cardiographic tracing of THE HEART BEAT, 545 the heart beat with results such as are shown in Fig. 233. Thefigure shows clearly the general fact that the first sound is heardvery shortly after the beginning of systole and the second oneimmediately after the end of systole. The first sound is thereforesystolic, and the second sound diastolic. A more exact and de-tailed study of the time relations of the heart sounds has been madeby Einthoven and Geluk.* These authors obtained graphic
A text-book of physiology for medical students and physicians . number ofobservers have recorded the time upon a cardiographic tracing of THE HEART BEAT, 545 the heart beat with results such as are shown in Fig. 233. Thefigure shows clearly the general fact that the first sound is heardvery shortly after the beginning of systole and the second oneimmediately after the end of systole. The first sound is thereforesystolic, and the second sound diastolic. A more exact and de-tailed study of the time relations of the heart sounds has been madeby Einthoven and Geluk.* These authors obtained graphic recordsof the heart sounds. The sounds received first by a microphonewere transmitted to a capillary electrometer and the movementsof the latter were photographed. As one result of their work theygive the schema shown in Fig. 234. It will be seen from this figurethat the first sound begins about sec. before the cardiogramshows the commencement of systole, and that for the first sound is heard only over the apex of the heart (a-b). Over the. ojsee. Fig. 234.—Schematic representation of the relation of the heart sounds to the ventric-ular beat: C, The cardiogram; 1, to show the duration of the first heart sound; 2, theduration of the second heart sound; S, the time record, each division corresponding sec. In 1, a-a marks the instant that the first heart sound is heard over the apex,and b-b the moment that it is heard at the second intercostal space.—(Einthoven andGeluk.) base of the heart (second intercostal space) the first sound is heard(b to c-d) just at the time when the semilunar valves are opened(&),—that is, at the beginning of the period of emptying accordingto the classification given on p. 539. The first sound ceases longbefore the ventricular contraction itself is over,—a fact whichwould seem to indicate that the muscular element in the first soundis not a muscular sound, such as is given out by a contractingskeletal muscle. The beginn
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Keywords: ., bookautho, bookcentury1900, bookdecade1910, booksubjectphysiology
