File:A manual of human physiology, including histology and microscopical anatomy, with special reference to the requirements of practical medicine (1885) (14781379865).jpg

Identifier: manualofhumanphy01land (find matches)
Title: A manual of human physiology, including histology and microscopical anatomy, with special reference to the requirements of practical medicine
Year: 1885 (1880s)
Authors: Landois, L. (Leonard), 1837-1902 Stirling, William, 1851-1932
Subjects: Physiology Histology
Publisher: Philadelphia, P. Blakiston, Son, and Company
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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urve—SPHYGMOGRAM or ARTERIOGRAM—we candistinguish the ascending part(ascent) of the curve, the apex,and the descending part (descent).Secondary elevations scarcelyever occur in the ascent, whichis usually represented by astraight line, while they occurconstantly in the descent. Suchelevations occurring in the de-scent are called catacrotic, andthose in the ascent, anacrotic(Landois). When the recoilelevation or dicrotic wave occursin a well-marked form in thedescent, the pulse is said to bedicrotic, and when it occurs twice,tricrotic. Measuring Pulse-Curves.—If the smoked surface on which the tracingis inscribed is moved at a uniformrate by means of the clock-work,then the height and length of thecurve are measured by means of anordinary rule. If we know the rateat which the paper was moved, thenit is easy to calculate the duration ofany event in the curve. For exactobservation a low-power microscopewith a micrometer in the eye-pieceshould be used,fixing the tracings see p, 130.
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Fig. 54. Pulse-curves of the carotid, radial, andposterial tibial arteries of a healthystudent, obtained by Landois angio-graph writing upon a plate attachedto a vibrating tuning-fork. Eachdouble vibration corresponds to0-01613 sec. For the method of smoking the paper and LANDOIS GAS-SPHYGMOSCOPE. 135 It is very convenient to write the curve upon a plate of glass fixedto a tuning-fork kept in vibration. Every part of the curve showslittle elevations (whose rate of vibration is known beforehand). Allthat is required is to count the number of vibrations in order toascertain the duration of any part of the curve. Fig. 54 was taken in this way from (A) the carotid, (B) the radial,and (C) the posterior tibial arteries of a healthy student. The results are:— 1-2,1-3, 1-4,1-5, Carotid. 717 23-556 Radial. 7 1622-539 PosteriorTibiaL 8192849 This method has also been used for the registration of other physiologicalprocesses—e.g., contraction of muscle. Landois Gas-SphyglUOSCOpe.—A superfi

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