. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine . Heart.—There is generalagreement in the view that the second sound is owing to theclosure of the semilunar valves of the aortic and pulmonaryvessels ; the former, owing to their greater tension in conse-quence of the higher blood-pressure in the aorta, taking muchthe larger share in the production of the sound, as may beascertained by listening over these vessels in the exposed these valves are hooked back, the second sound disap-pears, so that there can be no doubt that the
. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine . Heart.—There is generalagreement in the view that the second sound is owing to theclosure of the semilunar valves of the aortic and pulmonaryvessels ; the former, owing to their greater tension in conse-quence of the higher blood-pressure in the aorta, taking muchthe larger share in the production of the sound, as may beascertained by listening over these vessels in the exposed these valves are hooked back, the second sound disap-pears, so that there can be no doubt that they bear some impor-tant relation to the causation of the sound. In regard to the first sound of the heart the greatest diversityof opinion has prevailed and still continues to exist. The fol-lowing among other views have been advocated by physiolo-gists : 1. The first sound is caused by the tension and vibration ofthe auriculo-ventricular valves. 2. The first sound is owing to the contractions of the largemass of muscle composing the ventricles. 3. The sound is directly traceable to eddies in the
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1890
