form of eye drops to treat glaucoma
and work by lowering the fluid pressure
in the eyeball.
Beta-blockers may reduce an individ-
ual’s capacity for strenuous exercise.
The drugs may worsen the symptoms
of asthma, bronchitis, or other forms of
lung disease. They may also reduce the
flow of blood to the limbs, causing cold
hands and feet. In addition, sleep dis-
turbance and depression can be side
effects of beta-blockers.
betahistineA drug used to treat Mén-
ière’s disease, reducing the frequency
and severity of the attacks of nausea
and vertigo.
betamethasoneA corticosteroid drug
used to treat inflammation. Betametha-
sone is applied to the skin as cream to
treat contact dermatitis and eczema. It is
also prescribed as nasal spray to treat
allergic rhinitis.
Betamethasone is taken by mouth to
treat some cases of asthmaand arthritis.
Adverse effects are unlikely with short-
term use. However, prolonged topical
use of the drug can cause thinning of
the skin and may aggravate any infec-
tion. Taken orally for a prolonged period
or in high doses, betamethasone can
cause adverse effects typical of other
corticosteroid drugs.
bezoarA ball of food and mucus, veg-
etable fibre, hair, or other indigestible
material, in the stomach. Trichobezoars,
which are composed of hair, may form
in children or emotionally disturbed
adults who nibble at, or pull out and
swallow, their hair. Symptoms include
loss of appetite, constipation, nausea
and vomiting, and abdominal pain. If
trichobezoars pass into the intestines,
they may cause obstruction (see intes-
tine,obstruction of). Bezoars can be
removed endoscopically or surgically.
bi-The prefix meaning 2 or twice, as in
bilateral (2-sided).
bicarbonate of sodaSee sodium bi-
carbonate.
biceps muscleThe name given to a
muscle originating as 2 separate parts,
which then fuse. It is the commonly
used name for the biceps brachii mus-
cle of the upper arm, which bends
the arm at the elbow and rotates the
forearm. The biceps femoris at the back
of the thigh bends the leg at the knee
and extends the thigh.
bicuspidA term meaning to have 2 cusps
(curved, pointed structures). Bicuspid
describes certain heart valvesand is
used as an alternative name for a pre-
molar tooth (see teeth).
bifocalA spectacle lens with 2 different
focal lengths. Glasses with bifocal len-
ses make corrections for both close and
distant vision.
bilateralA term that means affecting
both sides of the body, or affecting both
organs if they are paired (for example,
both ears in bilateral deafness).
bileA greenish-brown alkaline liquid
secreted by the liver. Bile carries away
waste products formed in the liver and
also helps to break down fats in the
small intestine for digestion.
The waste products in bile include the
pigments bilirubinand biliverdin, which
give bile its greenish-brown colour; bile
salts, which aid in the breakdown and
absorption of fats; and cholesterol. Bile
passes out of the liver through the bile
ducts and is then concentrated and
stored in the gallbladder. After a meal,
bile is expelled and enters the duode-
num (the first section of the small
intestine) via the common bile duct.
Most of the bile salts are later reab-
sorbed into the bloodstream to be
recycled by the liver into bile. Bile pig-
ments are excreted in the faeces. (See
also biliary system; colestyramine.)BETAHISTINE BILE
BicepsTricepsHumerusUlnaRadiusBICEPS MUSCLETwo heads of biceps B