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The Body Electric
Semiconduction: The conduction of electrical current by the movement of
electrons or "holes" (the absence of electrons) through a crystal lattice. It is
the third and most recently discovered method of electrical conduction.
The others are metallic conduction, which works by means of electrons
traveling along a wire, and ionic conduction, which works by movement
of charged atoms (ions) in an electrolyte. Semiconductors conduct less cur-
rent than metals but are far more versatile than either of the other types of
conduction. Thus they are the basic materials of the transistors and inte-
grated circuits used in most electronic devices today.
Superconduction: The conduction of an electrical current by a specific material
that under certain circumstances (generally very low temperatures) offers
no resistance to the flow. Such a current will continue undiminished as
long as the necessary circumstances are maintained.
Synapse: The junction between one nerve cell and another, or between a nerve
cell and some other cell. See also Neurotransmitter.
Undifferentiated: Unspecialized, a term applied to cells that are in a primitive
or embryonic state. See also Dedifferentiation, Differentiation, Re-
differentiation .
Vertebrate: Any of the animals that have backbones, including all fish, am-
phibians, reptiles, birds, and mammals. All vertebrates share the same
basic anatomical arrangement, with a backbone, four extremities, and sim-
ilar construction of the muscular, nervous, and circulatory systems.