OESTROGEN HORMONES
OLIGOSPERMIA
Oestrogen drugs are often used together
with
progestogen drugs
.
Oestrogens suppress the production
of
gonadotrophin
hormones
,
which
stimulate cell activity in the
ovaries
.
High doses are used in postcoital con-
traception to prevent conception (see
contraception, emergency
). They are also
used to treat, or sometimes prevent,
menopausal symptoms and disorders.
Oestrogens may be used to treat certain
forms of
infertility
, female
hypogonadism
,
abnormal menstrual bleeding, prostatic
cancer (see
prostate, cancer of
), and cer-
tain types of
breast cancer
.
Oestrogens may cause breast tender-
ness and enlargement, bloating, weight
gain, nausea, reduced sex drive, depres-
sion, migraine, and bleeding between
periods. Side effects often subside after
2 or 3 months. The drugs can increase
the risk of abnormal blood clotting and
susceptibility to high blood pressure (see
hypertension
). Oestrogen drugs should
not be taken in pregnancy as they may
adversely affect the fetus.
oestrogen hormones
A group of
hor-
mones
that are essential for normal
female sexual development and healthy
functioning of the reproductive system.
In women, they are produced mainly in
the
ovaries
and also in the
placenta
in
pregnancy. Small amounts are pro-
duced in the
adrenal glands
in both
men and women, but oestrogens have
no known specific function in men. When
levels are low, oestrogen hormones can
be replaced with
oestrogen drugs
.
oestrone
See
estrone
.
ofloxacin
A
quinolone
antibiotic used to
treat skin, soft tissue, and lower
respira-
tory tract
and
urinary tract infections
.
It is
usually taken in tablet form to treat infec-
tions that have not responded to other
drugs but is also given by intravenous
infusion for severe
systemic
infections.
Side effects may include nausea, vomit-
ing, diarrhoea, and abdominal pain.
oils
See
fats and oils.
ointment
A greasy preparation used as
a vehicle to apply drugs in dry skin con-
ditions such as
eczema
or to protect or
lubricate the skin.
olanzapine
An
antipsychotic drug
used
for the treatment of
schizophrenia
.
olecranon
In the arm, the bony projec-
tion at the upper end of the
ulna
that
forms the point of the elbow.
olfactory nerve
The first
cranial nerve,
which conveys sensations of smell as
nerve impulses from the nose to the
brain. Each of the
2
olfactory nerves has
receptors in the mucous membrane lin-
ing the nasal cavity. These receptors
detect smells and send signals along
nerve fibres, which pass through tiny
holes in the roof of the nasal cavity and
combine to form the olfactory bulbs.
From here, nerve fibres come together
to form the olfactory nerve, leading to
the olfactory centre in the brain. Sense
of smell may be lost or impaired due to
damage to the olfactory nerves, usually
as a result of head injury.
OLFACTORY NERVE
oligo-
A prefix meaning few, scanty or
little, as in
oligospermia
(too few
sperm
in the
semen
).
oligodendroglioma
A rare and slow-
growing type of primary
brain tumour
mainly affecting young or middle-aged
adults. Surgical removal of the tumour
can, in some cases, lead to a total cure.
oligohydramnios
A rare condition in
pregnancy in which there is insufficient
amniotic fluid
surrounding the fetus in
the uterus.
oligospermia
A temporary or perma-
nent deficiency in the number of
sperm
in the
semen
. Oligospermia is a major
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