Medical clinics of the Hospital Necker, or, Researches and observations on the nature, treatment, and physical causes of diseases. Tr. from the French.

  • Isidore Bricheteau
Date:
1837
Catalogue details

Licence: Public Domain Mark

Credit: Medical clinics of the Hospital Necker, or, Researches and observations on the nature, treatment, and physical causes of diseases. Tr. from the French. Source: Wellcome Collection.

Provider: This material has been provided by the University of Massachusetts Medical School, Lamar Soutter Library, through the Medical Heritage Library. The original may be consulted at the Lamar Soutter Library at the University of Massachusetts Medical School.

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    head with loss of substance, leave no doubt as to the impulsion which that viscus communicates, during its systole, to the brain. This theory of the encephalic movements has been long demon- strated by the experiments of M. Richerand.* What is the degree of impulsion which the blood sent by the heart communicates to the brain ? Can it be estimated by that v/hich sets in motion, at each contraction of the heart, a weight of fifty pounds suspended to the lower hmbs? Or can we admit, with M. Poiseulle,^ that the total force which moves the blood in an artery is in a direct ratio with the area of the circle of the artery; or in a direct ratio with the square of its diameter, whatever may be the place it occupies ? Without replying to these questions, which are accessory to our object, and perhaps not capable of being solved, I may remark that some physiologists have endeavoured to diminish the force of impulsion of the blood on the encephalon, by advancing, that the elbow formed by the carotid canal retards the course of the fluid ; but in order that this should occur, we must suppose the arterial system to be emptied at the instant when the left ventricle sends the blood to the brain, which is never the case; consequently the curvature of the carotid, like that of other vessels, can have no influence on the progressive velocity of the blood sent by the heart.^ The degree, then, of impulsion communicated by tbe circulation to the encephalon is solely in a ratio with the quantity of blood carried to it: this quantity, according to the calculations—which, it must be admitted, are sufficiently imprecise—of Keil and Haller, being nearly one half [?] of the whole of the blood contained in the animal economy. Natural phenomena, like potent medicines, produce disorder when they are carried beyond the proper measure; thus, the access of blood to the brain, which in the healthy state is the natural exci- tant of that organ, becomes, when it is too impetuous, the cause of different symptoms; so that the integrity of the functions of the brain is associated not only with the movement communicated to it by the blood, but also with the amount of this movement, which must have a physiological mean. When too feeble or too impe- tuous, it is equally injurious. The experiments of which we have spoken, and the opinions which we have emitted, sufficiently prove this. ' Eleraens de Physiologie—Memoires de la Sociele Medicale d'Emula- tion. 3°annee. * Theses de Paris. ^ Were it necessary to give a trivial demonstration of this reasoning, and yet an entirely physical one, I might say, that by curving in various direc- tions a tube filled with water, and adapting to it a piston, we may see that the impulsion given it by the piston has the same result, as if the appa- ratus was straight; that is, the jet is continuous.—B. Yet the author, farther on, appears to support the opposite view. It is well known that the jet from a pipe of a regulai curve, connected with a reser- voir, rises much higher than from a pipe, the curve of which is less, or which is angular.—E. D.
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