The elastic properties of the arterial wall / by Charles S. Roy.

  • Roy Charles S. (Charles Smart)
Date:
1880
Catalogue details

Licence: Public Domain Mark

Credit: The elastic properties of the arterial wall / by Charles S. Roy. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    Exp. 6.—Strip of human aorta, 1 cm. broad, taken transversely. Length when stretched by weight of 50 grammes = 8-32 cm. Time. Temperature. Length. 2.55 p.m. 16-5 8-32 3.15 „ 22-0 8-256 3.35 „ 25*0 8-205 4.0 „ 300 8-155 4.20 „ 40'0 8-099 5.0 „ 17-5 8-295 Animal tissues must, then, be classed along with caoutchouc and bismuth, as exceptions to the general rule that heat causes expansion and cold contraction. They also, in accordance with the thermo-dynamic theory of Thomson, become warmer on being stretched and colder on being again relaxed. I shall have occasion to return to the thermo- elastic properties of animal tissues in considering the form of the curve of longitudinal elasticity of tho arterial wall. II. Viscosity1 of Animal Tissues2. In experiments on the longitudinal elasticity of animal tissues care must constantly be taken that error is not introduced owing to the disturbing influence of the elasticity after-action (elastische Nadiwirlamg). This phenomenon, which was first investigated by E. Weber3, consists, as is well known, in a secondary gradual expansion or contraction, lasting, it may be, for hours or even days after the primary expansion or contraction. When, for example, a strip of arterial wall, hung up by one extremity is stretched, by means of weights attached to its lower end, it does not at once attain the full degree of expansion which will finally be produced by the weight employed, but, after having stretched rapidly to a certain length, it continues gradually and 1 I see no reason why the term “ viscosity,” should not be applied to the molecular friction, or internal resistance, which must be looked upon as the cause of the after- action. The after-action is a phenomenon, and not a property, and some word is required which can express conveniently the causal molecular condition. Should further investi- gations show that the viscosity of metals, discovered by Thomson, is something essentially different in nature from the viscosity which causes the after-action, it will then be time enough to give the latter a distinctive name. 2 I have not made any connected series of experiments on this subject, and by rights it should not be referred to at length in a communication of this kind. I have, however, thought it advisable to say something on the subject, because, so far as I know, nothing is contained in English physiological literature concerning the elasticity after-action. 3 Poggendorf’s Annalen, 1841.