- Julius Bernstein
Julius Bernstein (
December 18 ,1839 -February 6 ,1917 ) was a Germanphysiologist who was born inBerlin . He studied medicine at theUniversity of Breslau underRudolf Heidenhain , and at theUniversity of Berlin underEmil Du Bois-Reymond . He received his medical degree at Berlin in 1862, and began his career at the Physiological Institute of theUniversity of Heidelberg as an assistant toHermann von Helmholtz . In 1872 he succeededFriedrich Goltz as professor of physiology at theUniversity of Halle . Bernstein remained in Halle for the remainder of his career.Bernstein's work was concentrated in the fields of
neurobiology andbiophysics . He is remembered for his explanation regarding the origin of the "resting potential" and "action potential" of nerves and muscles. In 1902 he developed the "membrane theory" of electrical potential in biological cells and tissues, which provided the first practical physico-chemical explanation of bioelectric events. This hypothesis is considered the first actual quantitative theory inelectrophysiology .Bernstein (1902, 1912) correctly proposed that excitable cells are surrounded by a membrane selectively permeable to K+ion s at rest and that during excitation the membrane permeability to other ions increases. His "membrane hypothesis" explained the resting potential of nerve and muscle as a diffusion potential set up by the tendency of positively charged ions to diffuse from their high concentration incytoplasm to their low concentration in the extracellular solution while other ions are held back. During excitation, the internal negativity would be lost transiently as other ions are allowed to diffuse across the membrane, effectively short-circuiting the K+ diffusion potential. In the English-language literature, the words "membrane breakdown" were used to describe Bernstein's view of excitation. (From "Ion Channels of Excitable Membranes", Third Edition, by Bertil Hille).His pioneering research laid the groundwork for experimentation on the conduction of the nerve impulse, and the transmission of information in the
nervous system . Bernstein also invented a "differential rheotome", a device used to measure thevelocity of bio-electric impulses.Written Works
* " [http://vlp.mpiwg-berlin.mpg.de/references?id=lit8435 Untersuchungen über den Erregungsvorgang im Nerven- und Muskelsysteme] ", Heidelberg: Winter, 1871 (Experiments of the excitation procedure in nerve and muscle systems)
* "Die fünf Sinne des Menschen". (The five senses of humans) Leipzig: Brockhaus, 1875
* "Die mechanische Theorie des Lebens, ihre Grundlagen und ihre Erfolge". Braunschweig: Vieweg, 1890
* "Lehrbuch der Physiologie des thierischen Organismus, im speciellen des Menschen". Stuttgart: F. Enke, 1894
* "Elektrobiologie: Die Lehre von den elektrischen Vorgängen im Organismus auf moderner Grundlage dargestellt". Braunschweig: Vieweg, 1912References
* [http://www.bernstein-zentren.de/_media/Seyfarth_Bernstein_BC94(06).pdf Julius Bernstein, Pioneer Neurobiologist and Biophysicist]
* [http://vlp.mpiwg-berlin.mpg.de/references?id=per51 Short biography, bibliography, and links on digitized sources] in theVirtual Laboratory of theMax Planck Institute for the History of Science
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