. Kirkes' handbook of physiology . if a continuous roll of unsmoked paper be used, thetrace is made by an inked pen) when a figure similar to figure 186 will beobtained. This indicates two main variations of the blood pressure. Thesmaller excursions of the lever correspond with the systole and diastole of theheart, and the larger curves correspond with the respirations, being calledthe respiratory undulations of blood pressure, to which attention will be directedin the next chapter. Of course, the undulations spoken of are seen only inrecords of arterial blood pressure. They are more clearly m
. Kirkes' handbook of physiology . if a continuous roll of unsmoked paper be used, thetrace is made by an inked pen) when a figure similar to figure 186 will beobtained. This indicates two main variations of the blood pressure. Thesmaller excursions of the lever correspond with the systole and diastole of theheart, and the larger curves correspond with the respirations, being calledthe respiratory undulations of blood pressure, to which attention will be directedin the next chapter. Of course, the undulations spoken of are seen only inrecords of arterial blood pressure. They are more clearly marked in the ar-teries nearer the heart than in those more remote. The amount of thepressure in the smaller arteries as well as the indication of the systolic riseof pressure is, comparatively speaking, small. In order to record the details of the undulations of arterial pressure, it isbetter for some purposes to use the Hiirthle membrane manometer than themercurial manometer. Two views of this instrument are shown in figure Fig. 187.—Tracing of Normal Arterial Pressure Taken from the Rabbit with a Hiirthle Manom-eter. The horizontal lines show zero pressure. Time in seconds. (Dreyer.) The instrument consists of a hollow tube and cup covered with rubber sheetagainst which a disc supported by a metal spring is adjusted. The apparatusis filled with fluid, the interior of which is connected with the artery by meansof a metal tube and cannula. The pressure transmitted to the apparatustends to stretch the rubber and bend the spring, and the movement thusproduced is communicated by means of a lever to a writing style and so toa recording apparatus. This instrument obviates the errors which mightbe caused by the inertia of the mercury in the mercurial manometer; it alsoshows in more detail the variations of the blood pressure in the vessel duringand after each individual beat of the heart. As regards the actual amount of blood pressure, from observations whichhave been made by
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