snake bites Most snake bites are by non-
venomous species. Venomous snakes are
found mainly in the tropics; the only
species native to the UK is the adder.
The effects of a venomous bite depend
on the species and size of the snake,
the amount of venom injected, and the
age and health of the victim. A bite from
an adder or other viper typically causes
immediate pain and swelling at the site,
followed by dizziness and nausea, a
drop in blood pressure, an increase in
heart-rate, and internal bleeding.
injections are given for all bites to pre-
vent infection and tetanus. An injection
is also given for a ven-
omous bite. With prompt treatment,
most victims recover completely.
sneezing The involuntary expulsion of air
through the nose and mouth as a result
of irritation of the upper respiratory tract.
This may be due to the common
, the presence of mucus,
or inhaling an irritant substance.
Snellen chart A method of measuring
snoring Noisy breathing through the
open mouth during sleep, produced by
vibrations of the soft palate. Snoring is
often caused by a condition that hinders
breathing through the nose, such as a
, or enlarged
. Snoring is more common when
sleeping on the back. If the underlying
cause can be treated, snoring may stop.
Snoring is also a feature of
snow-blindness A common name for
snuff A preparation of powdered
(often with other substances) for
inhalation. Snuff is addictive because it
; it also irritates the
nasal lining and increases the risk of
cancer of the nose and throat.
snuffles A general term for nasal obstruc-
tion, especially in infants suffering from
respiratory tract infection.
social and communication disorders
A collective term for disorders such as
begin in childhood. Problems tend to
persist throughout life.
social skills training A form of behav-
iour modification in which individuals
are encouraged to improve their ability to
communicate. This is an important part
for people with
or those with chronic psych-
ological disorders, such as
is a commonly used tech-
nique in which various social situations
are simulated in order to improve the
individual's confidence and performance.
sociopathy An outdated term for
social personality disorder.
that helps to regulate
the body's water balance and maintain
normal heart rhythm and is involved in
conduction of nerve impulses and con-
traction of muscles. The level of sodium
in the blood is controlled by the kidneys,
which eliminate any excess in the urine.
Almost all foods contain sodium natu-
rally or as an ingredient added during
processing or cooking. Consequently,
deficiency is rare and is usually the
result of excessive loss of the mineral
through persistent diarrhoea or vomiting,
or profuse sweating. Symptoms include
weakness, dizziness, and muscle cramps.
In severe cases, there may be a drop in
blood pressure, leading to confusion,
fainting, and palpitations. Treatment is
with supplements. In hot climates, sodium
supplements may help to prevent
by compensating for sodium
lost through heavy sweating.
Excessive sodium intake is thought to
be a contributory factor in
Another adverse effect is fluid reten-
tion, which, in severe cases, may cause
dizziness and swelling of the legs.
sodium aurothiomalate A preparation
that is given by injection.
used to relieve
, and pain caused
It often causes belching
and abdominal discomfort. Long-term
use may cause swollen ankles, muscle
cramps, tiredness, and nausea.
sodium cromoglicate A drug given by
inhaler to control mild
dren and allergic or exercise-induced
asthma in adults; as a nasal spray to
; in eye-drops for
; and orally for
. Side effects include coughing
and throat irritation on inhalation.