Book contents
- Frontmatter
- Contents
- Preface
- Publishers' Note
- Chapter 1 Structural organization of the nervous system
- Chapter 2 Resting and action potentials
- Chapter 3 The ionic permeability of the nerve membrane
- Chapter 4 Membrane permeability changes during excitation
- Chapter 5 Voltage-gated ion channels
- Chapter 6 Cable theory and saltatory conduction
- Chapter 7 Neuromuscular transmission
- Chapter 8 Synaptic transmission in the nervous system
- Chapter 9 The mechanism of contraction in skeletal muscle
- Chapter 10 The activation of skeletal muscle
- Chapter 11 Contractile function in skeletal muscle
- Chapter 12 Cardiac muscle
- Chapter 13 Smooth muscle
- Further reading
- References
- Index
Chapter 2 - Resting and action potentials
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- Publishers' Note
- Chapter 1 Structural organization of the nervous system
- Chapter 2 Resting and action potentials
- Chapter 3 The ionic permeability of the nerve membrane
- Chapter 4 Membrane permeability changes during excitation
- Chapter 5 Voltage-gated ion channels
- Chapter 6 Cable theory and saltatory conduction
- Chapter 7 Neuromuscular transmission
- Chapter 8 Synaptic transmission in the nervous system
- Chapter 9 The mechanism of contraction in skeletal muscle
- Chapter 10 The activation of skeletal muscle
- Chapter 11 Contractile function in skeletal muscle
- Chapter 12 Cardiac muscle
- Chapter 13 Smooth muscle
- Further reading
- References
- Index
Summary
Electrophysiological recording methods
Although the nervous impulse is accompanied by effects that can under especially favourable conditions be detected with radioactive tracers, or by optical and thermal techniques, electrical recording methods normally provide much the most sensitive and convenient approach. A brief account is therefore necessary of some of the technical problems that arise in making good measurements both of steady electrical potentials and rapidly changing ones.
In order to record the potential difference between two points, electrodes connected to a suitable amplifier and recording system must be placed at each of them. If the investigation is only concerned with action potentials, fine platinum or tungsten wires can serve as electrodes, but any bare metal surface has the disadvantage of becoming polarized by the passage of electric current into or out of the solution with which it is in contact. When, therefore, the magnitude of the steady potential at the electrode tip is to be measured, non-polarizable or reversible electrodes must be used, for which the unavoidable contact potential between the metal and the solution is both small and constant. The simplest type of reversible electrode is provided by coating a silver wire electrolytically with AgCl, but for the most accurate measurements calomel (Hg/HgCl2) half-cells are best employed.
When the potential inside a cell is to be recorded, the electrode has to be very well insulated except at its tip, and so fine that it can penetrate the cell membrane with a minimum of damage and without giving rise to electrical leaks.
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- Information
- Nerve and Muscle , pp. 9 - 20Publisher: Cambridge University PressPrint publication year: 2011