urine flow from the bladder and/or a
longstanding urinary tract infection.
The most common symptom of a stone
in the kidney or ureter is renal colic (a
severe pain in the loin) that may cause
nausea and vomiting. There may be
haematuria(blood in the urine). A blad-
der stone is usually indicated by
difficulty in passing urine. The site of
the stone can usually be confirmed by
intravenous or retrograde urography.
Renal colic is treated with bed rest
and an opioid analgesic(painkiller). With
an adequate fluid intake, small stones
are usually passed in the urine without
problems. The first line of treatment for
larger stones is lithotripsy, which uses
ultrasonic or shock waves to disinte-
grate the stones. Alternatively, cytoscopy
can be used to crush and remove stones
in the bladder and lower ureter. In some
cases, surgery may be needed.
calendar methodA method of contra-
ception,also called the rhythm method,
based on abstaining from sexual inter-
course around the time of ovulation
(calculated by a woman’s menstrual
cycles). The method is unreliable be-
cause the menstrual cycle may vary (see
contraception, natural methods).
calf musclesThe muscles extending
from the back of the knee to the heel.
The gastrocnemius muscle starts be-
hind the knee and forms the bulky part
of the calf; under it is the soleus muscle
which starts at the back of the tibia
(shin). The 2 muscles join to form the
Achilles tendon, which connects them to
the heel. Contraction of the calf mus-
cles pulls the heel up and is important
in walking, running, and jumping. Pain
in these muscles occurs because of
cramp, sciatica, or, more rarely, deep
vein thrombosis. The calf muscles may
be affected by claudication(pain caused
by walking and relieved by rest).
caliper splintAn orthopaedicdevice
that corrects or controls a deformed leg
or supports a leg weakened by a muscu-
lar disorder, allowing a person to stand
and walk.
callositySee callus, skin.
callus, bonyA diffuse growth of new,
soft bone that forms as part of the heal-
ing process in a fracture. As healing
continues, the callus is replaced by hard-
er bone, and the original shape of the
bone is restored.
callus, skin An area of thickened skin,
usually on the hands or feet, caused by
regular or prolonged pressure or friction.
A corn is a callus on a toe. If corns are
painful, the thickened skin can be pared
away by a chiropodist using a scalpel.
caloric testA method of finding out
whether the labyrinthin the inner ear is
diseased. It is performed as part of in-
vestigations into vertigo(dizziness) and
hearing loss. The outer-ear canal of the
ear is briefly flooded with water at dif-
ferent temperatures. If the labyrinth is
normal, nystagmus (rapid reflex flicker-
ing of the eyes) occurs for a predictable
period. If the labyrinth is diseased, the
response is absent or reduced.
calorieA unit of energy. One calorie is
the amount of energy needed to raise
the temperature of 1 gram of water by
1°C. However, the term calorie is also
used in medicine and dieteticsto mean
kilocalorie, a larger unit equal to 1,000
calories. Normally, when calorie intake
matches the amount of energy expended,
body weight remains constant. If intake
exceeds expenditure, weight is usually
gained; if expenditure exceeds intake,
weight is usually lost. In general, fats
contain the most calories. Energy can
also be measured in joules: 1 calorie
equals 4.2 joules. (See also calorimetry;
diet and disease.)
calorie requirements See energy re-
quirements.
calorimetryThe measurement of the
calorievalue of foodstuffs or the energy
expenditure of a person. In direct calori-
metry, a small measure of food is burned
up inside a sealed container, which is
immersed in water. The rise in water
temperature that results is used to cal-
culate the calorie value.
Energy production in humans is mea-
sured by oxygenuptake. Every litre of
oxygen taken into the body produces 4.8
kilocalories of energy. Energy production
is calculated by comparing the percent-
age of oxygen in air inhaled and exhaled.
campylobacterA group of bacteria that
are among the most common causes of
gastrointestinal disorders. The bacteriaCALENDAR METHOD CAMPYLOBACTER
C