. Electro-physiology. Electrophysiology. ELECTROMOTIArE ACTION IN NERVE 337. Hermann showed, the electromotive action of the conducting tissues is perhaps of the first importance. In view of the fact that muscle as well as nerve can be excited by its own demar- cation current, as well as by the current of action of a second preparation, provided the conditions of short-circuiting are other- wise favourable, it is prima facie not improbable that the internal short-circuiting of the action current may be an essential factor in the wave of negative excitation (or contraction) also. If with Herman
. Electro-physiology. Electrophysiology. ELECTROMOTIArE ACTION IN NERVE 337. Hermann showed, the electromotive action of the conducting tissues is perhaps of the first importance. In view of the fact that muscle as well as nerve can be excited by its own demar- cation current, as well as by the current of action of a second preparation, provided the conditions of short-circuiting are other- wise favourable, it is prima facie not improbable that the internal short-circuiting of the action current may be an essential factor in the wave of negative excitation (or contraction) also. If with Hermann (Handb. d. Physiol. i. 1, p. 256, and ii. 1, p. 194) we consider the galvanic action of any excited point with reference to its environment, this is found (as shown by Fig. '2'21, E} to consist in the "initiation of minor currents in its immediate vicinity," which are short-circuited within the indifferently conducting sheath of the electromotive tract. As in the immediate proximity of an artificial cross-section, numerous point of fibre. (Hermann.) lines of current find exit on both sides of the excited segment at the non-excited surface, and eventually effect an excitation there, while at the excited point itself there is, on account of the ingoing lines of current, a tendency to alteration in the opposite sense. Hermann makes express reference to the presumably high intensity of these minute currents, in which the short- circuiting lines are microscopic, so that the resistance is practically negligible. It is evident that a progressive wave of excitation may well be produced in this way. The Action of Nerve upon Muscle opens out a further question, which has as yet found no solution. Notwithstanding the fact that muscle possesses the same independent excitability as nerve, and as living protoplasm in general, the excitation of striated and smooth muscle occurs, in the majority of cases, indirectly from the nerve. The actual process of transmission is thus unknown
Size: 2081px × 1201px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1800, bookdecade1890, bookpublisherlondonmacmillan
