B. Khodorov

The Problem of Excitability (eBook, PDF)

Electrical Excitability and Ionic Permeability of the Nerve Membrane

• Format: PDF

Produktbeschreibung

The Russian edition of this book appeared in 1969 and im mediately gained widespread recognition as a reference work for research workers interested in the physiology, biophysics, and pharmacology of excitable tissues. There are several reasons for the book's success. It deals with a key problem in biology which has recently been the subject of very intensive study and it is of great interest to a wide scientific audience. Not only the fundamentals of the modern membrane theory of biopotentials, but also the vast factual material collected in the last decades by the study of the biophysical and pharmacological properties of the ionic permeability pores of the cell membrane, are described in the book in an authoritative yet readable form. Special attention is paid in the book to the systematic analysis of the consequences of the Hodgkin-Huxley mathematical theory of the nervous impulse for the problem of excitability. The relationship between the various parameters of excitability (threshold potential, threshold current, useful time), accommodation, and the action potential on the one hand, and the constants of ionic permeability of the nerve fiber membrane, on the other hand, is subjected to detailed examination in this context. To do this, the author has made extensive use not only of experimental results obtained on isolated fibers (especially single nodes of Ran vier), but also the results of his own investigations on mathematical models of excitable membranes.

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Produktdetails

• Verlag: Springer US
• Seitenzahl: 330
• Erscheinungstermin: 6. Dezember 2012
• Englisch
• ISBN-13: 9781461344872
• Artikelnr.: 44052984

Inhaltsangabe

I. Excitability and Relationships Between the Initial and Critical Values of the Membrane Potential.- Changes in Vt associated with primary shifts of Er.- Changes in Vt resulting from a primary shift of Ec.- II. The Resting Potential.- III. Passive and Subthreshold Active Changes in the Membrane Potential.- Passive changes of membrane potential.- The local response.- IV. The Action Potential.- Historical.- Effect of changes in external and internal sodium and potassium ion concentrations on action potential generation.- Movement of ions through the membrane during activity.- Evidence for subdivision of the ionic currents.- Changes in ionic permeability.- Quantitative description of ionic currents.- V. Dependence of Action Potential Parameters on the Constants of Membrane Ionic Permeability.- Maximal sodium permeability $$rm overline P _{Na} $$Na.- Steady-state sodium inactivation (1 - h?) and time constant Th.- Reactivity of the sodium system (sensitivity of PNa to changes in membrane potential).- The threshold potential.- Maximal steepness of rise of the ascending phase of the action potential.- Amplitude of the action potential.- Duration of the action potential.- Time constant of sodium activation Tm.- Maximal potassium permeability $$rm overline P _K $$.- Reactivity of the potassium system (sensitivity of $$rm overline P _K $$ to changes in membrane potential).- Effects of an increase in reactivity of thepotassium system.- Effects of a decrease in reactivity of the potassium activating system.- Time constant of potassium activation (Tn).- Assessment of the character of changes in ionic permeability of the membrane from changes in the action potential.- VI. Analysis of Threshold Conditions of Stimulation and the Relationship Between the Threshold Current andThreshold Potential.- The strength versus duration curve.- Character of critical depolarization of the membrane during the action of pulses of current of different duration. Nature of the utilization time.- Relationship between the threshold current and the passive and active properties of the membrane.- VII. Role of the Rate of Change of the Stimulus. The Phenomenon of Accommodation.- The accommodation curve.- The mechanism of accommodation.- Minimal gradient as a function of the constants of ionic permeability of the membrane.- Accommodation and repetitive responses.- VIII. Cable Properties and Geometry of Excitable Structures and Parameters of Their Electrical Activity.- The propagated action potential.- Threshold conditions of stimulation.- The threshold potential.- The threshold current.- The strength versus duration curve.- Repetitive responses in a continuous axon.- Effects of stimulation of excitable structures with a functionally nonuniform membrane.- The relationship between the velocity of conductance of the action potential and the cable properties and excitability of the fiber.- Conduction of impulses along a nonuniform fiber.- Some properties of spike conduction from a medullated into a nonmedullated segment of a nerve fiber.- Compensatory changes in ionic currents during conduction of the impulse along a nonuniform fiber.- IX. Molecular Mechanisms of Ionic Permeability of the Excitable Membrane.- Functional architecture of the excitable membrane.- The hypothesis of ionic carriers.- The hypothesis of ion pores.- Hypotheses on conformational changes in the membrane.- Investigations of mechanisms of the changes in ionic permeability on artificial membranes.- Precipitation membranes.- Phospholipid membranes.- Conclusion.- Addendum.