Identifier: physiologybioche00macl (find matches)
Title: Physiology and biochemistry in modern medicine
Year: 1918 (1910s)
Authors: Macleod, John James Rickard, 1876-1935 Pearce, R. G. (Roy Gentry), 1884-
Subjects: Physiology Biochemistry
Publisher: St. Louis : Mosby
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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f the flow, while the 202 THE CIRCULATION OP THE BLOOD other—the distal tube—being bent down stream, records merely lateralpressure. A photographic record of the movement of the fluid in thetwo tubes gives the velocity pulse (see Fig. 58). For physiologic pur-poses the form of apparatus used is constructed as shown in Fig. 59. Palpable Pulse.—To secure a record of the palpable pulse, the so-called sphygmograph is employed, although a tambour having a buttonin the center which is made to press on the artery may also be em-ployed. The commonest form of sphygmograph is that known asDudgeons (Fig. 60). It consists of a small button connected with aspring, the movements of which are transmitted and magnified by meansof a system of levers connected with a writing point arranged so asto inscribe its movements on a moving surface. The Analysis of the Curve The general contour of the pulse waves taken by any of the abovemethods are in general very much the same. The pressure and velocity
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Fig. 61.—Pulse tracing (sphygmogram) taken by sphygmograph. a d, the period of the pulsecurve; b, the primary; c, the dicrotic wave. Time marked in fifths of a second. (From Prac-tical Physiology.) pulse curves are, however, not usually taken for the purpose of observ-ing the contour of the wave but rather for measuring the difference inpressure or velocity actually produced during each pulse. It is a recordof the palpable pulse that is usually employed for studying the contourof the wave and the presence of secondary waves. A record of the pal-pable pulse wave (Fig. 61) shows two separate waves on the descendinglimb of the main wave. If a large number of similar pulse curves aretaken from different individuals or from the same individual underdifferent conditions, it will be found that of these two waves the secondone is by far the more constant; and if the waves are timed in relation-ship to the heart sounds, this second wave always occurs immediatelyafter the second sound, allowa

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