UMBILICUS
URETHRITIS
Umbilical hernias sometimes develop
in adults, especially in women after
childbirth.
Surgery may be necessary for
a large, persistent, or disfiguring hernia.
umbilicus The scar on the abdomen
that marks the site of attachment of the
umbilical cord
to the
fetus.
It is com-
monly called the navel.
unconscious A specific part of the mind
in which ideas, memories, perceptions,
or feelings that a person is not currently
aware of are stored and processed. The
contents of the unconscious mind are
not easily retrieved, in contrast to those
of the
subconscious.
(See also
Freudian
theory; Jungian theory.)
unconsciousness An abnormal loss of
awareness of self and one's surroundings
due to a reduced level of activity in the
reticular formation of the
brainstem
. An
unconscious person can be roused only
with difficulty or not at all. Unconscious-
ness may be brief and light, as in
fainting
,
or deep and prolonged (see
coma
).
underbite See
prognathism.
unsaturated fats See
fats and oHs.
unstable bladder Another name for
irritable bladder.
uraemia The presence of excess
urea
and other chemical waste products in
the blood, caused by
kidney failure
.
uranium A radioactive metallic element
that does not occur naturally in its pure
form but is widely found in ores such as
pitchblende, carnotite, and uraninite.
Radioactive decay of uranium yields a
series of radioactive products, including
radium
and
radon.
During the various
decay stages,
radiation
is emitted. Ura-
nium is also poisonous.
urea A waste product of the breakdown
of proteins by the liver that is transpor-
ted to the kidneys and eliminated in the
urine. Urea is also formed in the body
from the breakdown of cell proteins.
Kid-
n ey failure
impairs the kidneys' ability
to eliminate urea and leads to uraemia;
measurement of blood levels of urea is a
routine kidney function test. Urea is
used in various creams and ointments
to treat skin disorders such as
psoriasis
.
ureter One of the 2 tubes that carry urine
from the
kidneys
to the
bladder.
Each
ureter is 25-30 cm long. There are 3 lay-
ers in the walls of the ureters: a fibrous
outer layer; muscular middle layer; and
inner watertight layer. Each ureter is sup-
plied by blood vessels and nerves. Urine
flows down the ureters partly from grav-
ity but mainly as a result of
peristalsis.
Some people are born with double
ureters, on
1
or both sides of the body.
This sometimes causes
reflux
of urine,
incontinence
, or infection.
ureteric colic See
renal colic
.
ureterolithotomy The surgical removal
of a stone (see
calculus, urinary tract
)
stuck in a
ureter.
It is not commonly
needed because
lithotripsy
and
cysto-
scopy
can be used to deal with stones.
urethra The tube through which
urine
is
excreted from the
bladder
. In females, it
is short and opens to the outside in
front of the vagina. In males, it is much
longer, is surrounded by the prostate
gland at its upper end, and forms a
channel through the length of the penis.
urethral dilatation The procedure in
which a
urethral stricture
in a male is
widened by inserting a slim, round-
tipped instrument through the opening
of the
urethra
at the tip of the
penis.
urethral discharge A fluid that flows
from the
urethra
in some cases of
ure-
thritis
caused by infection.
urethral stricture A rare condition in
which the male
urethra
becomes nar-
rowed and sometimes shortened as a
result of shrinkage of scar tissue within
its walls. Scar tissue may form after
injury to the urethra or after persistent
urethritis
. The stricture may make passing
urine or ejaculation difficult or painful,
and it may cause some deformation of
the penis when erect. Treatment is usu-
ally by
urethral dilatation
.
urethral syndrome, acute A set of
symptoms, usually affecting women,
that are very similar to
cystitis
but which
occur in the absence of infection.
urethritis Inflammation of the
urethra
,
usually due to an infection but some-
times having other causes.
Urethritis may be caused by various
infectious organisms, including the bac-
terium that causes
gonorrhoea. Non-
gonococcal urethritis
may be caused by
any of a large number of different types
of microorganisms. Urethritis may also
be caused by damage from an accident
U
569
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