Carpenter's principles of human physiology (1881) (14781101362)

Identifier: carpentersprinci00carp (find matches)

Title: Carpenter's principles of human physiology

Year: 1881 (1880s)

Authors: Carpenter, William Benjamin, 1813-1885 Meneses, Henry Power

Subjects: Human physiology Physiology

Publisher: London : J. & A. Churchill

Contributing Library: Francis A. Countway Library of Medicine

Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

Text Appearing Before Image:

321gives a normal tracing ofarterial pressure obtainedwith the mercurial Kymo-graph from a rabbit. Poi-seuille estimated the pres-sure in the arteries at 6*3inches of mercury on thesquare inch, which he as-sumed as the standard forall arteries, and for all Mam-malia. But the tracings of Lud-wig and Volkmann showedthat the range of variation isvery wide, being in the carotid of the Horse from 6-13 inches, in the Dogfrom 7-8 inches, and in the Rabbit from 2-3 J inches; in Man it is probablyabout equal in the larger arteries to a column of mercury 8 inches in height(Ranke, 6 or 7 Faivre). Bernard has invented a lighter instrument, termedthe Cardiometer, the indications given by which are somewhat higher thanthose obtained by Poiseuilles apparatus. The following table presents theresults of Volkmanns observations! upon the relative lateral pressure at fourpoints of the circulation in different animals, expressed in millimetres—namely,* Bernard, vol. i. p. 205, 1859. f Op. tit., p. 173.

Text Appearing After Image:

Differential Manometer of Bernard.* 320 OF THE CIRCULATION OF THE BLOOD. (i.) the carotid near its origin, (n.) a peripheral branch of the carotid or someother artery, (in.) a peripheral rootlet of a vein, and (iv.) a jugular vein :— i. ii. in. IV. Goat . . . . 135 .. 126 . . 41 . 18 mm. Horse . . 122 .. 97 . . 44-5 . . 21:5 mm Calf . . . . 165-5 . .. 146 . . 27 9 mm. Fig. 143. The periodic variations of the blood-pressure depend, on the one hand, upon the frequency and vigour of thecontractions of the heart, and, upon the other hand, onthe resistance the blood meets with in its passage throughthe smaller vessels. The pressure of the blood in thearteries rises with increased strength and frequency ofthe hearts action, since more blood is then pumpedinto them than can readily escape through the capil-laries. Hence we find that section of the vagus whichis followed by a quicker pulse, produces higher meanpressure, whilst stimulation of the vagus, which causesslowing of the pulse, is f

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1881

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