daughter cells identical to the parent
cells. Meiosisproduces egg (see ovum)
and spermcells that differ from their
parent cells in that they have only half
the normal number of chromosomes.
cellulitisA bacterial infection of the skin
and the tissues beneath it, usually affect-
ing the face, neck, or legs. Cellulitis is
most commonly caused by streptococci
bacteria, which enter the skin via a
wound. The affected area is hot, tender,
and red, and there may be fever and
chills. Untreated cellulitis at the site of a
woundmay progress to bacteraemiaand
septicaemiaor, occasionally, to gangrene.
Cellulitis is usually more severe in peo-
ple with reduced immune response, such
as those withdiabetes mellitusor an
immunodeficiency disorder. Treatment is
with an antibioticsuch as a penicillindrug
orerythromycin. (See also erysipelas.)
celsius scaleA temperature scale in
which the melting point of ice is zero
degrees (0°C) and the boiling point of
water is 100 degrees (100°C). On this
scale, normal body temperature is 37°C.
(See also Fahrenheit scale.)
cementumBone-like tissue surround-
ing the root of a tooth (see teeth).
centigrade scaleThe obsolete name
for the celsius scale.
central nervous systemThe anatomi-
cal term for the brainand spinal cord,
often abbreviated as CNS. The central
nervous system is made up of neurons
(nerve cells) and works in tandem with
the peripheral nervous system(PNS),
which carries signals between the CNS
and the rest of the body. The CNS is
responsible for receiving sensory infor-
mation from organs such as the eyes
and ears, analysing it, and then initiat-
ing an appropriate motor response. (See
also nervous system.)
centrifugeA machine that separates
the different components of a body fluid
for analysis. When a fluid such as blood
is spun at high speed around a central
axis, groups of particles of varying den-
sity, for example red and white blood
cells, are separated by centrifugal force.
cephalexinAn alternative spelling of
cefalexin, a common cephalosporin drug.
cephalhaematomaAn extensive, soft
swelling on the scalp of a newborn infant,which is caused by bleeding into the
space between the craniumand its
fibrous covering due to pressure on the
baby’s head during delivery. The swelling
is not serious and gradually subsides.
cephalicRelating to the head, as in
cephalic presentation, the head-first
position of a baby in the birth canal.
cephalopelvic disproportionA com-
plication of childbirth (see childbirth,
complications of) in which the mother’s
pelvis is too narrow in proportion to the
size of the baby’s head.
cephalosporin drugsA large group of
antibiotic drugsderived from the fungus
CEPHALOSPORIUM ACREMONIUM, which are
effective against a wide range of infec-
tions. Cephalosporins are used to treat
ear, throat, and respiratory tract infec-
tions, and conditions, such as urinary
tract infectionsand gonorrhoea,in which
the causative bacteria are resistant to
other types of antibiotics. Occasionally,
the drugs cause allergic reactions, such
as rash, itching, and fever. Rarely, anaphy-
lactic shockoccurs. Other side effects
include diarrhoea and blood disorders.
cerebellar ataxiaJerky, staggering gait
and other uncoordinated movements
caused by a disease of or damage to
the cerebellum. Other features include
dysarthria(slurred speech), hand tremor,
and nystagmus (abnormal jerky eye
movements). Possible causes include
stroke, multiple sclerosis, a brain tumour,
damage caused by alcohol dependence,
and degeneration of the cerebellum due
to an inherited disorder.
cerebellumA region of the brain behind
the brainstemconcerned with maintain-
ing posture and balance and coordinating
movement. The cerebellum is situated
behind the brainstemand has 2 hemi-
spheres. From the inner side of each
hemisphere arise 3 nerve fibre stalks,
which link up with different parts of the
brainstem and carry signals between
the cerebellum and the rest of the
brain. Nerve fibres from these stalks fan
out towards the deep folds of the cortex
(outer part) of each brain hemisphere,
which consists of layers of grey matter.
Information about the body’s posture
and the state of contraction or relax-
ation in its muscles is conveyed fromCELLULITIS CEREBELLUMC