A Chemical Sign of Life (1917)

Seitenzahl:

94

Gewicht:

150 g

Erschienen bei:

Cambridge Scholars Publishing

Kurzbeschreibung

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER IV EXCITATION AND CONDUCTION We have shown by this study of nerves that living matter must necessarily undergo metabolic activity and that without an increase of this activity protoplasm will not function. In short, to be excitable, the protoplasm must respire, and to be excited, its metabolic activity must be accelerated. It has also been demonstrated that the excited state travels along the fiber with simultaneous increase of the metabolism. Although our theme in this little volume is not a consideration of how this state of excitation is transmitted, but is rather an analysis of the conditions which characterize the irritable tissue, the relation between these two phenomena is so close that we shall consider certain facts which are directly concerned with them. The two phases of protoplasmic irritability are excitability and conductivity, or transmission, of this excitation. Since it is very difficult experimentally to produce excitation without conduction, we are accustomed to consider the fundamental processes underlying these two processes as probably identical. There are certain facts which are sometimes cited as evidence that these phenomena are not necessarily interdependent. In the case of localized and partial narcosis, for instance, local excitability in the narcotized portion does not disappear simultaneously with conductivity throughthis region, assuming, of course, that the same strength of current when stimulating in or above the narcotized part is made use of. Since we have no evidence that the resistance of the surrounding sheath of the fiber and that of the conducting medium are the same, we cannot assume that in both experiments the same strength of stimulus was really applied to the conducting portion. The non-transmissibility of the inhibitory ...

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Mehr von:  Shiro Tashiro, Cambridge Scholars Publishing