Bma Illustrated Medical Dictionary

of collagen, a protein in connective tissue,

causing weakness of small blood vessels

and poor wound healing. Haemorrhages

may occur anywhere in the body, includ-

ing the brain. In the skin, haemorrhages

result in bruising. Bleeding into the

gums and loosening of teeth are com-

mon. Bleeding into muscles and joints

causes pain. Scurvy is treated with large

doses of vitamin C. Bleeding stops in 24

hours, healing resumes, and muscle

and bone pain quickly disappear.

sealants, dentalPlastic coatings that

are applied to the chewing surfaces of

the back teethto help prevent decay.

seasicknessA type of motion sickness.

seasonal affective disorder syndrome

A form of depressionin which mood

changes occur with the seasons. Sufferers

tend to become depressed in winter and

feel better in spring. Exposure to bright

light for 2–4 hours each morning seems

to prevent occurrence in some people.

sebaceous cystA harmless smooth nod-

ule under the skin, most commonly on

the scalp, face, ear, and genitals. The

cyst contains a yellow, cheesy material

and may become very large and infected

by bacteria, making it painful. Large or

infected cysts can be surgically removed.

sebaceous glandsGlands in theskin

that secrete a lubricating substance called

sebum. Sebaceous glands either open

Scoliosis usually starts in childhood or
adolescence and becomes progressively
more marked until growth stops. In many
cases, another part of the spine curves
to compensate, resulting in an S-shaped
spine. The cause of juvenile scoliosis is
unknown. Rarely, scoliosis is due to a
congenital abnormality of the vertebrae.
In some cases, physiotherapymay be
sufficient to control scoliosis. Progressive
or severe scoliosis may require immobi-
lization of the spine in a brace, followed
by surgery (spinal fusion) to straighten it.
scorpion stingsInjection of venom by a
scorpion into a victim using a sting in its
tail. Manyspecies are not dangerous,
but some in North Africa, southern US,
South America, the Caribbean, and India
are highly venomous. Some stings may
cause only mild pain and tingling; but in
more venomous species severe pain,
restlessness, sweating, diarrhoea, and
vomiting can occur. Stings are rarely fatal
in adults but require prompt attention. If
pain is the only symptom, analgesics
and a cold compress may be enough. In
severe cases, antivenommay be needed.
scotomaAn area of abnormal vision
within the visual field.
screeningThe testing of apparently
healthy people with the aim of detect-
ing disease at an early, treatable stage.
(See also cancer screening.)
scrofulaTuberculosisof the lymph nodes
in the neck, often those just beneath the
angle of the jaw. Scrofula is rare in deve-
loped countries. Antituberculous drugs
clear up the condition in most cases.
scrotumThe pouch that hangs behind
the penis and contains the testes. It con-
sists of an outer layer of thin, wrinkled
skin over a layer of muscular tissue. Swel-
ling of the scrotum may be due to an
inguinal hernia, swollen testis, hydrocele,
or fluid accumulation due to heart failure.
scuba-diving medicineA medical spe-
cialityconcerned with the physiological
hazards of diving with self-contained
underwater breathing apparatus. Most
hazards stem from the pressure increase
with depth. Conditions treated include
burst lung and decompression sickness.
scurvyA disease, now rare in developed
countries,caused by inadequate vitamin
Cintake. Scurvy disturbsthe production

SCORPION STINGS SEBACEOUS GLANDS

S

Sebaceous

gland

Fat

Hair

SEBACEOUS GLANDS

Arrector pili

muscle

Hair

follicle

Sebum

Skin

surface