. Eight lectures on the signs of life from their electrical aspect. Electrophysiology. •] MUSCLE CURRENTS of the amount of vitality possessed by muscle. A weak muscle can do less work than a strong muscle, and a given muscle in the course of fatigue, or of that last act of life that we call death, can give less and less extensive contraction, and effect a smaller and smaller amount of work. Paripassic with declin- ing contraction we witness declining electromotive response, and we admit or assume that the common substratum of the decline, whether mechanical or electrical, is decline of chemica
. Eight lectures on the signs of life from their electrical aspect. Electrophysiology. •] MUSCLE CURRENTS of the amount of vitality possessed by muscle. A weak muscle can do less work than a strong muscle, and a given muscle in the course of fatigue, or of that last act of life that we call death, can give less and less extensive contraction, and effect a smaller and smaller amount of work. Paripassic with declin- ing contraction we witness declining electromotive response, and we admit or assume that the common substratum of the decline, whether mechanical or electrical, is decline of chemical activity. An excised muscle has been set up to show this parallelism between mechanical and electrical response. A lever attached to the tendon indicates to you, by its excursion on a smoked glass plate, the extent or height of the mechanical movements (contraction). A galvanometer connected to the muscle by. MechdnicaL Response. ELectnc< Response. Fig. 2.—Simultaneous records of a series of muscular contractions, and of the corresponding series of negative variations. The method and apparatus for obtaining such records is described in the Appendix, p. l6o, Fig. 63. wires and unpolarisable electrodes, indicates to you, by the excursion of the reflected spot of light, the extent or voltage of the accompanying electrical movements. The muscle is excited indirectly, by excitation of its nerve, and, as you see, the two sets of movements, mechanical and electrical, run an approxi- mately parallel course—both are large together or small to- gether, and if one is absent, so is the other. You would notice, however, on closer comparison, that the parallelism is not perfect, the mechanical and electrical responses are not an exact replica of each other, and the defect of correspondence is particularly apparent in simultaneous records of the two sets of responses. I cannot at present enter further upon this difference, I think it requires further study; if you ask which of t
Size: 3242px × 771px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyo, bookyear1903
