On the properties of the arterial and venous walls / by J.A. MacWilliam.

  • John Alexander MacWilliam
Date:
[1901]
Catalogue details

Licence: In copyright

Credit: On the properties of the arterial and venous walls / by J.A. MacWilliam. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    death is used, the series of increasing extensions is broken by a number of smaller extensions to give place again to larger increments. This is probably due to a contractile reaction of the muscular tissue of the strip against the stretching force, or is a result of mechanical stimula- tion caused by the clamps grasping each end of the strip. (Fig. 19.) Repeated Stretching.—When a transverse strip is weighted in the way described and then unloaded, and after a time again weighted in the same way, a second tracing is obtained differing very strikingly from the first. It is in fact essentially similar to that obtained from a strip of relaxed artery. The extension caused by the first weight is very great. A third experiment of the same sort gives residts essentially similar to those of the second experiment. (Figs. 18 and 19.) Fig. 19.—Carotid (ox), contracted. Transverse strip. During the first loading the largest extensions were followed by two or three small oneB; these were succeeded by decidedly larger ones which gradually diminished in size. ™ Longitudinal Strip of Contracted Artery.—-With strips of similar dimen- sions cut longitudinally from the arterial wall, the total elongation produced by a total load similar to that used with transverse strips (e.g., 240 340 grammes) is very much less than with]transverse strips —commonly between a half and a third. The character of the tracing differs in the two cases. In the longi- tudinal strip there is only a slight increase, if any, in the amount of elongation produced as the earlier weights are added, then a progres- sive diminution. After unloading, the longitudinal strip recovers much more readily and completely than the transverse strip ; the former shortens quite to its original length. (Fig. 20.) Further, a repetition of the process of loading does not cause the striking alteration in the tracing seen with the transverse strip ; with