ABSTRACT
CONTENTS 5.1 Introduction ....................................................................................................................... 115 5.2 Maxwell’s Equations and the Properties of Materials .............................................. 116 5.3 Physics of the Interactions of Electric Fields with Biological Materials ................. 117 5.4 Biological Amplification ................................................................................................. 127 5.5 Effects of Electric Fields on Cell Membranes ............................................................. 128 5.6 Nonlinear Effects of AC Fields on Cells ....................................................................... 132
5.6.1 Introduction ........................................................................................................... 132 5.6.2 Rectification by Cell Membranes ....................................................................... 133
5.7 Thermal Effects ................................................................................................................. 144 5.8 Natural Fields and Man-Made Fields ........................................................................... 147 5.9 Discussion and Summary................................................................................................ 152 Acknowledgments ..................................................................................................................... 152 References ................................................................................................................................... 152
The fact that electrical currents can affect the behavior of biological systems has been known for more than 2000 years. Electric shocks have been used to treat a wide variety of ailments since the eighteenth century. However, our knowledge of how these fields and the resulting currents influence biological systems is surprisingly incomplete. Electrical signals are clearly important in the control of biological processes and in carrying information from one part of the body to another. Nerve cells propagate electrical signals from sensors of pressure, temperature, light, sound, etc., to the brain and return control signals to muscles and other tissue. Yet, if we choose to stimulate these processes with external electrical inputs, we have a relatively limited understanding of how a given electrical signal will affect various biological organs; what the safe limits of exposure are (particularly overextended periods of time); and how electrical signals are carried across cell membranes, are propagated along nerves, or affect growth processes and cell division.
