ELECTRICAL INJURY
E
electrical injury
Damage to tissues caused by an electric
current passing through the body and
the associated heat release. The internal
tissues of the body, being moist and
salty, are good conductors of electricity.
Dry skin provides a high resistance to
current flow, but moist skin has a low
resistance and thus allows a substantial
current to flow into the body. Serious
injury or death from domestic voltage
levels is therefore more likely to occur
in the presence of water.
PHYSICAL EFFECTS
All except the mildest electric shocks
may result in unconsciousness. Alternat-
ing current (A C ) is more dangerous
than direct current (D C ): it causes sus-
tained muscle contractions, w hich may
prevent the victim from releasing the
source of the current. A current as small
as
0.1
amp passing through the heart
can cause a fatal
arrhythmia
(irregular
heartbeat). The same current passing
through the
brainstem
may cause cessa-
tion of the heartbeat and breathing.
Larger currents may cause charring of
tissues, especially where
the current
enters and exits the body.
electric shock treatment
See
ECT
.
electrocardiography
See
ECG
.
electrocautery
A technique for destroying tissue using
heat produced by an electric current.
Electrocautery is used to remove skin
blemishes such as
warts
.
(See also
cauter-
ization
;
diathermy
;
electrocoagulation
. )
electrocoagulation
Use of a high-frequency electric current
to seal blood vessels by heat, stopping
bleeding
.
Electrocoagulation is used in
surgery; the current is delivered through
a surgical knife, enabling the surgeon to
make bloodless incisions. The procedure
is also used to stop nosebleeds and to
destroy abnormal blood vessel forma-
tions, such as
spider naevi
,
in w hich case
current is applied through a fine needle.
electroconvulsive therapy
See
ECT
.
electrode
A device through w hich an electrical
current is transmitted or received. In
ECG
,
for example, electrodes are applied
to the chest wall to detect electrical
impulses from the heart. Other proce-
dures using electrodes include certain
types of
physiotherapy,
in w hich elec-
trodes are attached to the skin and emit
electrical
impulses
to
stimulate
the
underlying
muscles.
(See
also
ECT;
electrocautery
;
electrocoagulation
;
electrol-
ysis; electronystagmography.)
electroencephalography
See
EEG.
electrolysis
Permanent removal of unwanted hair
by introducing a short-wave electric
current into the hair
follicle.The
current
destroys the hair root either by causing
a chemical reaction (a process that is
called galvanism) or by generating heat,
w hich seals off the blood vessels sup-
plying the hair (see
diathermy).
WHY IT
IS DONE
Hair on the face and body can be
removed
temporarily
by
shaving
or
plucking or by the use of depilatory
creams, abrasives, or wax preparations.
However, electrolysis is the only method
of permanent hair removal.
AREAS THAT CAN
BE TREATED
W ith a few exceptions, electrolysis can
be safely used on any part of the body.
Its use should be avoided on the lower
margins of the eyebrows because the
skin above the eyelids is very delicate
and easily damaged. It is also question-
able whether the technique should be
used on the armpits due to the risk of
bacterial infection. Electrolysis has no
harmful effect on the breasts (where
How
electrolysis is done
To remove each hair, a fine needle is inserted into
the follicle and a small electric current is passed
through it. The current destroys the root of the
hair and the hair is then pulled out. The procedure
may cause some pain, but, in skilled hands, it is
harmless. Ifthe treatment is successful, there
should be no further hair growth from that follicle.
hair sometimes grows around the are-
ola, the pigmented area surrounding
the nipple) and does not affect
breast-
feeding
.
The legs are not well suited to
electrolysis because treatment of this
extensive area requires so many sessions
that the procedure would be very time-
consuming and expensive.
NEWER TREATMENTS
Alternative methods of hair removal,
w hich are faster and less painful than
electrolysis, are now available.
One new method is a form of
laser
treatment
in w hich hair follicles are dis-
abled by a laser beam. The treatment can
be used on several hundred hair follicles
simultaneously. It works best on people
with pale skin and dark hair, because
the melanin (dark pigment) in the hair
absorbs energy from the laser, while the
skin (which has little melanin) is rela-
tively unaffected.
Another new technique, known as
photo-epilation,
involves
the
use
of
intense pulsed light to disable hundreds
of hair follicles at the same time, with
minimal side effects.
electrolyte
A substance whose molecules dissociate
(split) into its constituent
ions
(electri-
cally charged particles) when dissolved
or melted. For example, sodium chlo-
ride (table salt) dissociates into sodium
cations (positively charged ions) and
chloride anions (negatively charged ions)
when dissolved in water.
electromyography
See
EMG
.
electronystagmography
A method of recording types of
nys-
tagmus
(abnormal, jerky movements of
the eye) in order to investigate their
cause. In electronystagmography, elec-
trical changes caused by eye movements
are picked up by
electrodes
that are
placed near the eyes and are recorded
on a graph.
electrophoresis
The movement of electrically charged
particles that are suspended in a
colloid
solution under the influence of an elec-
tric current. The direction, distance, and
rate of movement of the particles vary
according
to
their
size,
shape,
and
electrical charge.
Electrophoresis
is
used
to
analyse
mixtures (to identify and quantify the
proteins in blood, for example), and it
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