bruitsThe sounds made in the heart,
arteries, or veins when blood circula-
tion becomes turbulent or flows at an
abnormal speed. This happens when
blood vessels become narrowed by dis-
ease (as in arteriosclerosis), when heart
valves are narrowed or damaged (as in
endocarditis), or if blood vessels dilate
(as in an aneurysm). Bruits are usually
heard through a stethoscope.
bruxismRhythmic grinding or clenching
of the teeth that usually occurs during
sleep. The chief underlying causes are
emotional stress and minor discomfort
when the teeth are brought together.
BSEThe abbreviation for bovine spongi-
form encephalopathy.
bubonic plagueThe most common
form of plague, characterized by the
development of a bubo (swollen lymph
node) in the groin or armpit.
buccalAn anatomical term, from the
Latin word for cheek, that means relat-
ing to the cheek or mouth. Some drugs
are available as buccal preparations,
which are placed between the cheek
and gum, where they dissolve and are
absorbed directly into the circulation.
buck teethProminent upper incisors
(front teeth), which protrude from the
mouth. Orthodontic treatment involves
repositioning the teeth with a remov-
able brace (see brace,dental) or a fixed
orthodontic appliance.
Budd–Chiari syndromeA rare disor-
der in which the veins draining blood
from the liver become blocked or nar-
rowed. Blood accumulates in the liver,
which swells. Liver failureand portal
hypertension result. Treatment is aimed
at removing the cause of the obstruction:
this may be a blood clot, pressure on
the veins from a liver tumour, or a con-
genital abnormality of the veins. In most
cases, treatment has only a limited effect
and, unless a liver transplantcan be
done, the disease is fatal within 2 years.
budesonideAn inhaled corticosteroid
drugused in the treatment of bronchial
asthmato prevent asthma attacks. It is
administered using an inhaler. Side
effects of budesonide, which include
hoarseness, throat irritation and, rarely,
fungal infections, can be reduced by
rinsing the mouth after administration.bronchospasmTemporary narrowing of
the bronchi (airways into the lungs) due
to contraction of the muscles in the
walls of the bronchi, by inflammation of
the lining of the bronchi, or by a combi-
nation of both. Contraction may be
triggered by the release of substances
during an allergic reaction (see allergy).
When the airways are narrowed, the air
is reduced, causing wheezing or cough-
ing. Asthmais the most common cause
of bronchospasm. Other causes include
respiratory infection, chronic obstructive
pulmonary disease (see pulmonary dis-
ease, chronic obstructive), anaphylactic
shock, or allergic reaction to chemicals.
bronchusA large air passage in a lung.
Each lung has 1 main bronchus, origi-
nating at the end of the trachea
(windpipe). This main bronchus divides
into smaller branches known as seg-
mental bronchi, which further divide
into bronchioles.
bronchus, cancer ofSee lung cancer.
brown fatA special type of fat, found in
infants and some animals. Brown fat is
located between and around the scapu-
lae (shoulderblades) on the back. It is a
source of energy and helps infants to
maintain a constant body temperature.
brucellosisA rare bacterial infection,
caused by various strains of BRUCELLA,
which may be transmitted to humans
from affected cattle, goats, and pigs.
Brucellosis may also be transmitted in
unpasteurized dairy products. Initially, it
causes a single bout of high fever, aches,
headache, backache, poor appetite, weak-
ness, and depression. Rarely, untreated
severe cases may lead to pneumoniaor
meningitis. In long-term brucellosis, bouts
of the illness recur over months or
years; and depression can be severe. The
disease is treated by antibiotic drugs.
bruiseA discoloured area under the
skin caused by leakage of blood from
damaged capillaries (tiny blood vessels).
At first, the blood appears blue or black;
then the breakdown of haemoglobin
turns the bruise yellow. If a bruise does
not fade after a week, or if bruises
appear for no apparent reason or are
severe after only minor injury, they may
be indications of a bleeding disorder.
(See also black eye; purpura.)BRONCHOSPASM BUDESONIDEB