. Elements of human physiology. Physiology. THE VASCULAR MECHANISM 221 ventricular pressure in animals, or the heart-sounds in man.' Applying the latter method we may obtain the curve shown in Fig. 119. In this curve it will be seen that the first heart-. Cardiogram (Hiirthle sound, corresponding to the ventricular systole, begins, not at the commencement of the rise of the cardiogram, but at the notch near the top of the ascent. From this fact we may Fig. 119. 1 â 1 ifV. _ ,\r. - _ _ __P=^^ Cardiogram (r.) with simultaneous record of heart-sounds (a) (Hiirthle). 1. Position of first heart-sou
. Elements of human physiology. Physiology. THE VASCULAR MECHANISM 221 ventricular pressure in animals, or the heart-sounds in man.' Applying the latter method we may obtain the curve shown in Fig. 119. In this curve it will be seen that the first heart-. Cardiogram (Hiirthle sound, corresponding to the ventricular systole, begins, not at the commencement of the rise of the cardiogram, but at the notch near the top of the ascent. From this fact we may Fig. 119. 1 â 1 ifV. _ ,\r. - _ _ __P=^^ Cardiogram (r.) with simultaneous record of heart-sounds (a) (Hiirthle). 1. Position of first heart-sound. 2. Position of second heart-sound. conclude that the first part of the ascent is caused by the auricular systole forcing blood into the ventricle, the ventri- ' This mechanical record of the heart-sounds has been successfully accomplished by Hiirthle. His method consists in an application of the microphone. A special form of stethoscope is so arranged that by its means the vibrations corresponding to the heart-sounds are transmitted to a contact between silver and carbon. Through this contact a strong current is passing. This also passes through an electro-magnet, which attracts an iron disc attached to the membrane of a Marey's tambour. Any vibration transmitted to the carbon-silver contact alters its resistance, and so the strength of the current passing through the electro-magnet. In this way the heart-sounds can affect the pull exerted by the electro-magnet on the membrane of the tambour, and the change in the volume of the contained air is recorded by means of an ordinary registering Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Starling, Ernest Henry, 1866-1927. Chicago : W. T. Keener
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