producing the pigment melanin. (See
also sunlight, adverse effects of; sunburn.)
superegoThe part of the personality,
as described in psychoanalytic theory,
that is responsible for maintaining a
person’s standards of behaviour. Popu-
larly termed the “conscience”, the
superego arises as a result of a child
incorporating the moral views of those
in authority (usually parents).
superficialSituated near the surface.
superinfectionA second infectionthat
occurs during the course of an existing
infection. The term usually refers to an
infection by a microorganism that is
resistant to drugs being used against
the original infection.
superiority complexAn individual’s
exaggerated and unrealistic belief that
he or she is better than other people. In
modern psychoanalytic theory, a superi-
ority complex is considered to be a
compensation for unconscious feelings
of inadequacy or low self-esteem.
supernumeraryA term meaning more
than the normal number.
supernumerary teethOne or more
teethin excess of the usual number.
These teeth are usually extracted.
supinationThe act of turning the body
to a supine position (lying on the back
with the face upward) or of turning the
hand to a palm forward position. The
opposite of supination is pronation.
suppositoryA solid medical prepara-
tion, of cone or bullet shape, designed
to be placed in the rectum to dissolve.
Suppositories are used to treat rectal
disorders such as haemorrhoids or
proctitis. They may also be used to soft-
en faeces and stimulate defaecation. In
addition, suppositories may be used to
administer drugs into the general circu-
lation, via blood vessels in the rectum, if
vomiting is likely to prevent absorption
after oral administration or if the drug
would cause irritation of the stomach.
suppurationThe formation or discharge
of pus.
suprarenal glandsAnother name for
the adrenal glands.
supraspinatus syndromeSee painful
arc syndrome.
supraventricular tachycardiaAn ab-
normally fast but regular heart-rate that
occurs in episodes lasting for several
hours or days. Supraventricular tachy-
cardia occurs when abnormal electrical
impulses that arise in the atria of the
hearttake control of the heartbeat from
the sinoatrial node. Symptoms include
palpitations, breathlessness, chest pain,
or fainting (see Stokes–Adams syndrome).
Diagnosis is by an ECG. An attack can
sometimes be terminated by Valsalva’s
manoeuvreor by drinking cold water.
Recurrent attacks are treated with anti-
arrhythmic drugs. Rarely, the condition
may require application of an electric
shock to the heart (see defibrillation).
surfactantA substance, such as a soap
or emulsifier, that reduces surface ten-
sion. Pulmonary surfactant is secreted by
the alveoli in the lungs, preventing them
from collapsing during exhalation, and
is absent in babies born significantly
prematurely. This deficiency causes
breathing difficulties, and the infant
needs artificial ventilationand the admin-
istration of an artificial surfactant.
surfer’s nodulesMultiple bony out-
growths on the foot bones and on the
bony prominence just below the knee.
surgeryThe treatment of disease, injury,
or other disorders by direct physical inter-
vention, or those aspects of medicine that
dealwith the study, diagnosis, and man-
agement of disorders treated in this way.
surgical spiritA liquid preparation,
consisting mainly of ethyl alcohol, that
has a soothing and hardening effect
when applied to the skin. It may be
used before injections as an antiseptic.
surrogacyThe agreement by a woman
to become pregnant and give birth to a
child with the understanding that she
will surrender the child after birth to the
contractual parents. Surrogacy may be
accomplished by artificial insemination
or by in vitro fertilization.
susceptibilityA total or partial vulner-
ability to an infection or disorder.
sutureA type of joint, found only be-
tween the bones of the skull, in which the
adjacent bones are mobile during birth
but then become so closely and firmly
joined by a layer of connective tissue that
movement between them is impossible.
The term suture is also used to refer
to a surgical stitch (see suturing).SUPEREGO SUTURE
S