I
The technique carries some risks, so it
is performed only when other tests,
such as
ultrasound scanning,
detect an
abnormality.
By
attaching
additional
instruments, doctors can use the feto-
scope to take samples of fetal blood or
tissue for analysis and to perform sur-
gical procedures, such as insertion of a
catheter into the fetal bladder. (See also
amniocentesis
;
chorionic villus sampling
. )
fetus
The unborn child from the end of the
eighth
week
after
conception
until
birth. For the first eight weeks, the
unborn child is called an
embryo
.
The fetus develops in the mother’s
uterus
in a sac filled w ith
amniotic fluid
,
w hich cushions it against injury. The
oxygen and nutrients required by the
fetus are supplied via the
placenta
,
an
organ embedded in the inner w all of
the uterus that is attached to the fetus
by the
umbilical cord
.
FEV
See
forced expiratoryvolume
.
fever
Known medically as pyrexia, elevation
of body temperature above the normal
level of 3 7°C in the mouth and 0.6°C
lower in the axilla (armpit). A fever may
be accompanied by symptoms such as
shivering, sweating, a headache, thirst,
unusually rapid breathing, and a flushed
face.
Confusion
or
delirium
sometimes
occur with a fever, especially in elderly
people. A high fever may cause seizures
in a child under five years (see
convul-
sion, febrile
) or
coma
.
CAUSES
Most
fevers
are
caused
either
by
bacterial infections, such as
tonsillitis
,
or by viral infections, such as
influenza
.
In such cases, proteins called pyrogens
are released when the white blood
cells fight the microorganisms that are
responsible
for
the
infection
(see
immune system
) .
Pyrogens act on the
temperature-controlling centre in the
brain, causing it to raise the tempera-
ture of the body in an attempt to
destroy the invading microorganisms.
Fever
may
also
occur
in
other
conditions
where
infection
is
not
present. Such conditions include
dehy-
dration
,
thyrotoxicosis
(a condition that
results from overactivity of the thyroid
gland),
lymphoma
(a tumour of the lym -
phatic system), and
myocardial infarction
(heart attack).
FIBRILLATION
TREATMENT
Drugs such as
aspirin
,
other
nonsteroidal
anti-inflammatory drugs
,
or
paracetamol
may be given to reduce fevers that are
due to infections. Otherwise, treatment
is directed at the underlying cause; for
example,
antibiotic drugs
are given to
treat a bacterial infection.
feverfew
The common name for the plant T
a n
-
a c e t u m
p a r t h e n i u m
, w hich is used in
herbal medicine for the treatment of
headache and migraine.
fibrates
A type of
lipid-lowering drug
that is used
to treat high blood levels of
triglycerides
or
cholesterol
.
fibre, dietary
The indigestible plant material in food.
Dietary fibre includes certain types of
polysaccharide,
cellulose,
hem icellu-
lose, lignin, and gums and pectins (see
carbohydrates
) .
Humans do not have
the enzymes necessary to digest these
substances,
so
the
material
passes
through the digestive system virtually
unchanged and cannot be used as a
source of energy.
Some components of dietary fibre
hold water, thereby adding bulk to the
faeces and aiding bowel function. For
this reason, dietary fibre can be effec-
tive in treating
constipation, diverticular
disease
,
and
irritable bowel syndrome
.
A high-fibre diet can help to reduce
blood cholesterol levels. Certain high-
fibre foods, such as fruit and vegetables,
are also beneficial in protecting against
cancers. Unrefined carbohydrate foods,
including
wholemeal
bread,
cereals,
and root vegetables, are very rich in
dietary fibre. (See also
nutrition
. )
fibre-optics
The transmission of images through
bundles
of
thin,
flexible
glass
or
plastic threads. Light from a powerful
external
source
is
conducted
along
the length o f the fibre, without losing
its intensity, by a process known as
total internal reflection.
Fibre-optics
have led to the development o f
endo-
scopes
,
instruments
that
enable
structures deep w ithin the body to be
viewed directly.
fibrillation
Localized, spontaneous, rapid contrac-
tions o f muscle fibres that can affect
both skeletal and heart muscle.
In skeletal muscle, fibrillation gener-
ally occurs when a nerve supplying a
muscle is destroyed, causing the mus-
cle to become weak and waste away.
Unlike
fasciculation
(muscular quiver-
ing), fibrillation in skeletal muscle is
not visible through the skin; instead,
the contractions can be detected using
an
EMG
(electromyogram).
Fibrillation in the heart muscle is
caused by disruption to the spread of
nerve impulses through the wall of one
of the chambers of the heart. Either the
upper chambers (see
atrial fibrillation
) or
the lower chambers (see
ventricular fib-
rillation
) o f the heart may be affected.
The condition can be detected by the
use of an
ECG
(electrocardiogram). Fib-
rillation
in
heart
muscle
has
the
F
GOOD SOURCES OF FIBRE (per
1 0 0
g portion)
Essential for the efficient working of the digestive system, fibre is usually eaten as
fruit or grains. Among the best sources are bran, apricots, prunes, and wholemeal
bread. Eating sufficient fibre in food can reduce constipation. The recommended
daily intake is
2 5
to
3 0
grams.
Wholemeal flour
9.6
Dried apricots
24
Peanuts
8.1
Celery
4.9
Peas
12
Raisins
6.4
Green beans
7.4
Prunes
16.1
Bran
44
.........
1
...........
1
..........
1
.........
1
............
1
..........
1.........
1
..........
1
...........
1
}
5
10
15
2 0
25
3 0
35
4 0
45
307
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