ORGANELLE
ORTHO-
organelle One of various specialized
structures contained within a body
cell.
organic Related to a body
organ;
hav-
ing organs or an organized structure; or
related to
organisms
or to substances
from them. In chemistry, “organic” refers
to certain compounds that contain car-
bon. In medicine, the term indicates the
presence of disease. (See also
inorganic.)
organic brain syndrome See
brain
syndrome, organic.
organism A general term for an individ-
ual animal or plant.
Bacteria
and
viruses
are disease-causing
microorganisms
.
organophosphates Highly poisonous
agricultural insecticides that are harm-
ful when absorbed through the skin, by
inhalation, or by swallowing. Among the
many possible symptoms are nausea,
vomiting, abdominal cramps, diarrhoea,
blurred vision, excessive sweating, head-
ache, confusion, and twitching. Severe
poisoning may cause breathing difficulty,
palpitations, seizures, and unconscious-
ness. If left untreated, death may result.
Treatment may include washing out the
stomach (see
lavage, gastric
) or removing
soiled clothing and washing contami-
nated skin. Injections of
atropine
may be
given, and
oxygen therapy
and/or artifi-
cial
ventilation
may be needed. With
rapid treatment, people may survive
doses that would otherwise have been
fatal. Long term effects of organophos-
phates in sheep dips are thought to be
responsible for debilitating illness with
neural, muscular, and mental symptoms.
orgasm Intense sensations produced
by a series of muscular contractions at
the peak of sexual excitement. Orgasm
usually lasts for about 3-10 seconds but
can last up to a minute in women.
In men, contractions of the muscles of
the inner pelvis massage seminal fluid
from the
prostate gland
into the
urethra
,
from which it is forcefully propelled via
the urethral orifice (see
ejaculation).
Orgasm in women is associated with
irregular contractions of the voluntary
muscles of the walls of the
vagina
and,
in some women, of the
uterus
, followed
by relief of congestion in the pelvic
area. Some women experience multiple
orgasms if stimulation is continued.
Orgasm is followed by a refractory phase
during which there is no physical re-
sponse to further sexual stimulation.
Both men and women may experience
problems with orgasm (see
ejaculation,
disorders of; orgasm, lack of).
orgasm, lack of Inability to achieve
orgasm during sexual activity. It may be
due to inhibited sexual desire (see
sexual
desire, inhibited
) or inability to become
aroused or maintain arousal (see
frigid-
ity
;
impotence
). In men, there may be a
problem achieving orgasm despite nor-
mal arousal (see
ejaculation, disorders of
).
The problem is common in women; some
may achieve orgasm through
masturba-
tion
but not during sexual intercourse.
Sometimes it is due to pain during
intercourse (see
intercourse, painful).
For both sexes, contributory factors
include problems with technique or in
the relationship, unfamiliarity with sex-
ual responses, psychological problems
(such as anxiety, early sexual trauma, or
inhibitions), and fear of pregnancy.
Sex
therapy
,
relationship counselling
, and
psychotherapy
are sometimes helpful.
orlistat An anti-obesity drug used with a
slimming diet to treat severe obesity.
Unlike
appetite suppressants,
orlistat acts
on the gastrointestinal tract, preventing
the digestion of fats by lipases (pancreat-
ic
enzymes).
Instead of being absorbed,
the fats pass out of the body in faeces.
Side effects are gastrointestinal and
can be minimized by reducing fat in-
take. Flatulence and faecal urgency are
common. Deficiencies of fat-soluble vit-
amins may develop with prolonged use.
ornithosis A disease of birds, caused by
the microorganism
chlamydia psittaq,
that can cause
psittacosis
in humans.
orphan drugs Drugs that have been
developed to treat rare conditions but
are not manufactured generally.
orphenadrine A
muscle-relaxant drug
used to treat painful muscle spasm due
to soft-tissue injury and
Parkinson's dis-
ease
. Side effects include a dry mouth
and blurred vision.
ORT An abbreviation for
oral rehydration
therapy.
(See also
rehydration therapy.)
ortho- A prefix meaning normal, correct,
or straight, as in
orthopaedics
, a branch
of surgery concerned with correcting dis-
orders of the bones and joints.
O
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