Biomedical Engineering Reference
In-Depth Information
Figure 18.3.
Nineteenth century “Electric Air Treatment” (Borgens 1989; McCaig et al. 2005).
Used with permission from The American Physiological Society.
“negative breeze” meant to cure a broad range of ailments, even baldness. A
metal receptor above the patient's head and a metal plate placed beneath the
patient acted as the cathode and anode, respectively. The metal plate was con-
nected to a static-electricity generator (inside a wooden cabinet in Figure 18.3). A
patient might be occasionally shocked due to faulty or incorrectly grounded
wires, but no therapeutic benefi t came from such a device (Borgens 1989).
Such treatments were stopped by the next century, thanks to knowledge
gained in human electrophysiology. However, the elimination of bogus treat-
ments did not bring demise to electrotherapeutic treatment. Instead, the fi eld
advanced as evidence began to show correlations between electricity and
anatomy. The role of electric fi elds (EFs) in tissues is still being investigated, but
now the fi eld of bioelectricity or electrical therapy is held with higher scientifi c
regard.
18.5.1 Physiological Endogenous Electric Fields
The well-known action potential, one of the most signifi cant discoveries in elec-
trophysiology, is a momentary reversal in the potential difference across a plasma
membrane (as in a nerve cell or muscle fi ber) that occurs when a cell has been
activated by a stimulus. The action potential is, in part, what makes neurons so
unique from most other cells in the body. However, there is another electrical
phenomenon discovered before the action potential, which is not usually men-
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