Otherwise, treatment is directed at the
underlying cause (for example, giving
antibiotic drugsfor a bacterial infection).
feverfewThe common name for the
plant TANACETUM PARTHENIUM, which is
used in herbal medicine to treat head-
ache and migraine.
fibratesA group of lipid-lowering drugs
used to treat high blood levels of tri-
glyceridesor cholesterol.
fibre, dietaryIndigestible plant mater-
ial in food. Dietary fibre includes certain
types of polysaccharides, cellulose,
hemicelluloses, gums and pectins (see
carbohydrates), and lignin. Humans do
not have the necessary enzymes to
digest these substances, which pass
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 rea-
son, dietary fibre can be effective in
treating constipation, diverticular disease,
and irritable bowel syndrome. Unrefined
carbohydrate foods such as wholemeal
bread, cereals, and root vegetables are
rich in fibre. (See also nutrition.)
fibre-opticsThe transmission of ima-
ges through bundles of thin, flexible
glass or plastic threads which propa-
gate light by total internal reflection.
This means that all the light from a
powerful external source travels the
length of the fibre without losing its
intensity. Fibre-optics have led to the
development of endoscopes, which en-
able structures deep within the body
to be viewed directly.
fibrillationLocalized spontaneous, rapid
contractions of individual muscle fibres.
Unlike fasciculation(muscular quiver-
ing), fibrillation cannot be seen through
the skin. In skeletal muscles, fibrillation
is detected by an EMG. In heart muscle,
it is detected by an ECG.
Fibrillation usually occurs once a nerve
supplying a muscle is destroyed, which
causes the affected muscle to become
weak and waste away. Fibrillation of the
heart muscle is caused by disruption to
the spread of nerve impulses through
the muscle wall of a heart chamber (see
atrial fibrillation; ventricular fibrillation).
fibrinA substance that is produced in
the blood during the process of blood
clotting. A dissolved protein called
fibrinogenis converted to fibrin, which
forms long filaments that bind clumps
of plateletsand other blood cells into a
mass which plugs the bleeding point.
fibrinogenA protein that is present in
blood and which is converted into fibrin
during the blood clottingprocess.
fibrinolysisThe breakdown of fibrin, the
principal component of any blood clot.
Fibrin is a stringy protein that is formed
in blood as the end product of coagula-
tion (see blood clotting). Blood also
contains a fibrinolytic system, which is
activated in parallel with the coagulation
system when a blood vessel is damaged.
The fibrinolytic system prevents the for-
mation of clots in undamaged blood
vessels, thereby preventing blockage, and
it dissolves a clot once a broken vessel
wall has healed. Thrombosis(abnormal
clot formation) occurs if there is a dis-
turbance in the balance between the
coagulation and fibrinolytic mechanisms.
fibrinolytic drugsAnother name for
thrombolytic drugs, which are used to
dissolve blood clots.
fibroadenomaA noncancerous fibrous
tumour most commonly found in the
breast. Fibroadenomas of the breast are
painless, firm, round lumps and are usu-
ally 1–5 cm in diameter and movable.
They occur most often in women under
30 and black women. Multiple tumours
may develop in one or both breasts.
The lumps are removed surgically and
the tissue examined to confirm diagnosis.
fibroadenosisAn outdated term for the
general lumpiness that is a normal fea-
ture of some women’s breasts. Cyclical
changes in hormone levels often lead
to lumpiness, which is more obvious
before a menstrual period. Lumpy
breasts do not increase the risk of deve-
loping breast cancer. However, a new
solitary, discrete breast lump should be
assessed by a doctor to rule out the
possibility of breast cancer.
fibrocystic diseaseA term used to
refer either to the inherited disorder
cystic fibrosisor the presence of general
lumpiness of the breasts that is a varia-
tion of normal. (See also fibroadenosis).FEVERFEW FIBROCYSTIC DISEASE
F