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

  • Bayliss, William Maddock, Sir, 1860-1924.
Date:
1923
Catalogue details

Licence: In copyright

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

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    vaso-constriction in the organ in question, but that an actual vaso-dilatation occurred therein. Loven (1866) first described the phenomenon in the rabbit’s ear on stimulation of the posterior auricular nerve, and in the case of the saphenous artery when the dorsalis pedis nerve was stim¬ ulated. Bradford (1889) found that stimulation of the central ends of the dorsal roots of the kidney area caused vaso¬ dilatation in the kidney. It is probable that the effect would be found to be more or less common to all organs if the appropriate nervous channels could be stimulated apart from the vaso-motor nerves. Figure 50 gives examples. In some cases, the reflex dilatation spreads to the cor¬ responding organ of the opposite side, but this is not very common. I found that reciprocal innervation holds here as in the general depressor reflex; that is, the dilatation is due both to excitation of dilators and to inhibition of constrictor [Explanation to Fig. 50.] A Upper curve — blood pressure. Lower curve — volume of upper part of hind leg of dog. At the Signal, the central end of the dorsalis pedis nerve of same leg was stimulated, causing a marked dilatation of the leg, with a slight fall in blood pressure. The usual rise of general pressure was absent here. B Upper curve — blood pressure. Lower curve drops of blood falling from cut femoral vein. At the signal, the central end of the anterior crural nerve of the same side was stimulated. A rise of blood pressure is seen, accompanied by vaso dilatation in the leg. Fig. 44 above shows that stimulation of a sensory nerve from another region, namely, that of the ann, causes vaso-constriction in the leg. The fact is also seen in C Upper curve — volume of hind leg of dog. Lower curve — blood pressure. Vaso-dilators cut off by section of lumbar and sacral dorsal roots. At the signal, the median nerve was stimulated. Rise of pressure, with constriction of the leer. o • D Same experiment as C, but the central end of a dorsal root of the leg area, the sixth lumbar, was stimulated. There is also rise of blood pressure, but the vessels of the leg dilate.