I
fluke
A type of flattened worm , also known
as a trematode, that may infest humans
or
animals. The
two
main
diseases
caused by flukes are
liver fluke
infesta-
tion,
w hich occurs worldwide,
and
schistosomiasis,
a
debilitating
disease
that is common in tropical countries.
flunitrazepam
A type of
benzodiazepine drug
that is
used as a sleeping drug in the treatment
of
insomnia
. T h e
effects of flunitrazepam
may persist into the following day. Pro-
longed use of this drug may result in
dependence (see
drug dependence
) .
Also
known as Rohypnol, or the “date-rape”
drug, flunitrazepam is a
controlled drug.
fluorescein
A harmless
orange
dye
(that
glows
green in contact with defective cells
when blue light is shone on it) used in
ophthalmology
to aid the diagnosis of
certain eye disorders. Fluorescein can be
applied to the front of the eye to detect
abrasions of the
conjunctiva
or
cornea
.
It
is also given intravenously during fluo-
rescein
angiography
in order to detect
abnormalities of the blood vessels in the
retina
(the light-sensitive inner layer at
the back of the eye), w hich occur in
such conditions as
macular degeneration
and
diabetic retinopathy
.
fluoridation
The addition of
fluoride
to the water
supply as a means of reducing the in ci-
dence of dental
caries
(tooth decay).
Some areas have naturally high levels
of fluoride in the drinking water; in
other areas, however, fluoride is added
to bring the concentration up to the
recommended level. In the UK, deci-
sions to add fluoride to drinking water
are made by the local authorities.
fluoride
A mineral that helps to prevent dental
caries
(tooth decay) by strengthening
tooth enamel
(see
teeth
) ,
making it
more resistant to acid attacks. Fluoride
may also reduce the acid-producing
ability of microorganisms in
plaque
.
Fluoride that is ingested during the
formation of teeth has a lifelong bene-
ficial effect because it is incorporated
into the developing tooth substance. In
the UK, fluoride is added to the water
supply, and fluoridation has led to a
decrease
in
the incidence
of tooth
decay among children.
FOLEY CATHETER
Fluoride is also beneficial to both chil-
dren and adults when it is applied
directly to the teeth as part of dental
treatment or used in the form of a
mouthwash or toothpaste. However, the
ingestion of excess fluoride as the teeth
are forming can lead to fluorosis (stain-
ing of the tooth enamel).
fluorosis
Mottling or staining of the tooth ena-
mel (see
teeth
)
that is caused by the
ingestion of excess
fluoride
as the teeth
are formed. In severe cases of fluorosis
the enamel develops brown stains. This
occurs principally in areas in w hich the
fluoride
level
in
water
exceeds
the
recommended
level
or
if additional
supplements are taken.
fluorouracil
An
anticancer drug
used in the treat-
ment of cancers of the breast, bladder,
ovaries, and intestine.
fluoxetine
An
antidepressant drug
that belongs to
a drug group called
selective serotonin
reuptake inhibitors
(SSRIs). SSRIs work
by increasing the amount of
serotonin
available in the brain and thus stimu-
lating brain cells. The most common
adverse
effects
include
restlessness,
insomnia, headache, and diarrhoea.
flupentixol
An
antipsychotic drug
used
to
treat
schizophrenia
and sim ilar illnesses. It is
also sometimes prescribed for
depres-
sion
.
Side
effects of the drug most
commonly
include
blurred
vision,
nausea, a rapid heartbeat,
dizziness,
and
parkinsonism
.
flurazepam
A type of
benzodiazepine drug
that is
used as a sleeping drug in the treat-
ment of
insomnia
.
The drug’s effects
may persist the following
day. Pro-
longed use may result in dependence
(see
drug dependence
).
flurbiprofen
A
nonsteroidal anti-inflammatory drug
that
is used particularly to ease the symp-
toms
of
musculoskeletal
disorders,
such as
rheumatoid arthritis
.
flush
Reddening of the face, and sometimes
of the neck, caused by dilation of the
blood vessels near the skin surface.
Flushing may occur during
fever
or as a
result of embarrassment.
Hot flushes
are
common at the
menopause
.
fluticasone
A
corticosteroid drug
taken in the form
of an inhaler to control
asthma
,
as a
nasal spray to relieve the symptoms of
allergic rhinitis
(see
rhinitis allergic
) ,
and as an ointment or cream to treat
dermatitis
and
eczema
.
Side effects are rare, but may include
nosebleeds when the drug is taken as a
nasal spray,
candidiasis
(thrush) of the
mouth and throat when taken as an
inhaler, and skin irritation when taken
as an ointment or cream.
Flynn-Aird syndrome
A rare, inherited disorder that is charac-
terized by
atrophy
(wasting away) of the
muscles and skin,
ataxia
(incoordination
and clumsiness), and dementia. Other
symptoms
of
Flynn-Aird
syndrome
include tooth decay (see
caries, dental
),
stiffness in the joints,
retinitis pigmentosa
(degeneration of the rods and cones
of the
retina
), peripheral
neuropathy
(a
peripheral
nerve
disorder),
cataracts
,
and progressive loss of hearing. Flynn-
Aird syndrome shows an autosomal
dominant pattern of inheritance (see
genetic disorders
) .
foam, contraceptive
See
spermicides
.
focal point
The point at w hich light rays converge
after passing through a
lens
.
In people
w ith norm al vision, light rays from a
viewed object converge on the light-
sensitive
retina
after passing through
the cornea and lens, producing a clear
image. In shortsightedness, the focal
point occurs in front of the retina and
the image is blurred; in longsighted-
ness, it occurs beyond the retina, with
the same result.
foetus
An alternative spelling for
fetus
.
Foley catheter
A type of
catheter
(flexible tube) that
is fed through the
urethra
into the
bladder
and used for the continuous
drainage of
urine
(see
catheterization,
urinary
). A Foley catheter is kept in
place w ithin the
bladder
by means of a
balloon at its tip that is inflated with
either air or liquid.
F
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