The vaso-motor system / by Sir William M. Bayliss.

  • William Bayliss
Date:
1923
Catalogue details

Licence: In copyright

Credit: The vaso-motor system / by Sir William M. Bayliss. Source: Wellcome Collection.

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    REA CTION TO STRETCHING. Smooth muscle in various situations has been shown to respond to the stimulus of stretching by contraction. Such cases are the muscular tube of the earthworm (Straub,. 1900), and the stomach of the frog (Winkler, 1898). The frog’s heart sometimes ceases to beat when empty, but can be excited to contraction by distension with liquid. Wharton Jones (1852) noticed that the rhythmic contractions of the veins of the bat’s wing are directly dependent on the pressure within them. Certain phenomena noticed in blood vessels have been interpreted as due to similar pro* perties. In the course of experiments made for other pur¬ poses, I found that the volume of a limb whose nerves were cut was at first increased by a rise of arterial pressure,, as would naturally be expected. But this distension was followed, on return of the blood pressure to the original level, by a contraction much beyond that which corresponded previously to this height of blood pressure (Bayliss, 1902). At the time when these experiments were made, it was not known that the suprarenal gland could be stimulated through its nervous supply to send out adrenaline into the blood stream. This was shown by Elliott (1912). Anrep (1912) pointed out that all the methods used in my ex¬ periments were such as might cause a secretion of adrena¬ line and that it is unnecessary to assume a contractile re¬ sponse of the arterial muscle to distension. This fact does not, of course, exclude the possibility of such a response and the explanation of the opposite reaction to decreased tension is not quite so satisfactory. Figure 11 shows the large relaxation produced in the arterioles of the limb in consequence of a fall of pressure produced by brief closure of the femoral artery. This is regarded by Anrep as being due to the production of vaso-dilator substances in con-
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