BACTERIURIA
B
bacteriuria
The presence of
bacteria
in the urine. It
is common for small, harmless numbers
of bacteria to be found in the urine of
healthy people. Bacteriuria is of signi-
ficance only if more than
1 0 0 ,0 0 0
bacteria are present in each millilitre of
urine, or if
1 0 0
white blood cells (pus
cells) per millilitre of urine are present
(which is an indication of the body’s
response to the infection).
Bacteroides
A genus of
anaerobic
(capable of living
without
oxygen)
bacilli
(rod-shaped
bacteria
) that normally inhabit the intes-
tines. One particular type, B
acteroides
fragieis
, is commonly found in abdomi-
nal wound infections and in the blood
when the intestines are diseased.
bad breath
See
halitosis.
bagassosis
An occupational disease affecting the
lungs of workers who handle mouldy
bagasse (the fibrous residue of sugar-
cane after juice extraction). Bagassosis is
one cause of allergic
alveolitis,
a reaction
of the lungs to inhaled dust containing
fungal spores. Symptoms develop four
to five hours after inhalation of the dust
and may include shortness of breath,
wheezing, fever, headache, and cough;
typically, they last for about 24 hours.
Repeated exposure to dust may lead
to permanent lung damage. Protective
measures taken by industry have made
the disease rare.
Baker’s cyst
A firm, fluid-filled lump behind the
knee. A Baker’s cyst occurs as a result of
increased pressure in the knee joint due
to a buildup of fluid. Such a buildup is
a feature of disorders such as
rheumatoid
arthritis.
The cyst is created by a back-
ward ballooning-out of the synovial
membrane covering the knee joint.
Most Baker’s cysts are painless, and
some disappear spontaneously, some-
times after many months. Occasionally,
a cyst may rupture, causing fluid to seep
down between the layers of the calf mus-
cles. This can produce pain and swelling
in the calf that may mimic a deep vein
thrombosis (see
thrombosis, deep vein).
Diagnosis of a Baker’s cyst is con-
firmed by
ultrasound
scanning.Treatment
is rarely needed, but in a few cases
surgery may be performed.
balance
The ability to remain upright and move
without falling over. Keeping one’s bal-
ance is a complex process that relies on
a constant flow of information to the
brain about body position. The integra-
tion of all of this information, and
continual instructions from the brain,
enable the body to make the changes
needed to maintain balance.
The brain receives data on body posi-
tion from various sources: the eyes; the
sensory organs (called proprioceptors)
in the skin, muscles, and joints; and the
three semicircular canals of the labyrinth
of the inner
ear.
The part of the brain
called the
cerebellum
collates this infor-
mation and sends instructions to muscles
to contract or relax to maintain balance.
DISORDERS
Balance can be affected by various dis-
orders, particularly inner-ear disorders
such as
labyrinthitis
(inflammation of
the ear’s labyrinth) and
Ménière’s disease
(an abnormally high pressure of fluid in
the labyrinth). Less commonly,
otitis
media
(a disorder of the middle ear)
may disturb balance.
Damage to nerve tracts in the spinal
cord that carry information from posi-
tion sensors in the joints and muscles to
the brain can also impair balance. This
damage to the nerves may result from
spinal tumours, circulatory disorders,
nerve degeneration due to deficiency of
vitamin B12, or, rarely, tabes dorsalis (a
complication of
syphilis).
A tumour or
stroke
that affects the cerebellum in the
brain may cause clumsiness of the arms
and legs as well as other features of
impaired muscular coordination.
balanitis
Inflammation of the foreskin and the
glans
(head)
of the penis. Balanitis
results in pain and/or itchiness, and the
entire area may be red and moist. Causes
of balanitis include bacterial or fungal
infection,
phimosis
(tightness
of the
foreskin), or chemical irritation by con-
traceptive creams (see
contraception)
or
laundry products.
Treatment is usually with
antibiotic
drugs
or
antifungal drugs
(either applied
to the skin as cream or taken orally) and
careful washing of the penis and foreskin.
If balanitis recurs frequently, or is due to
phimosis,
circumcision
(surgical removal
of the foreskin) may be recommended.
baldness
See
alopecia.
ball-and-socket joint
A highly mobile
joint,
such as the shoul-
der or hip.
ballismus
Violent jerking and twitching of the
limbs that is caused by brain damage
within the area below the
thalamus
(a
structure that relays sensory informa-
tion). In most cases, only one side of
the body is affected, in which case the
condition is known as hemiballismus.
balloon angioplasty
See
angioplasty, balloon
.
ballottement
A technique occasionally used during a
physical examination (see
examination,
physical
) to check the position of an
organ, particularly in a fluid-filled area
of the body. It involves flicking or tap-
ping the area with the fingers, causing
the organ to move up and down. The
technique was once widely used to con-
firm pregnancy; when the wall of the
uterus is tapped, the fetus moves away
and floats back with a responding tap.
balloon catheter
A flexible tube with a balloon at its tip,
which, when inflated, keeps the tube in
place or applies pressure to an organ or
vessel. One type of balloon catheter is
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