CAVITY, ABDOMINAL
C
Thrombus in cavernous sinus
The clot obstructs blood flow in the cavernous
sinus, causing pressure behind the eye socket.
and eye movements may be paralysed
due to pressure on the
optic nerve
and
other cranial nerves.
TREATMENT
Treatment w ith
antibiotic drugs
and
anti-
coagulant drugs
can save vision. Left
untreated, blindness w ill result, and the
infection may eventually prove fatal.
cavity, abdominal
........
~ ........
See
abdomen.
cavity, dental
A hole in a tooth, commonly caused by
dental caries (see
caries,
cavity, oral
dental).
See
mouth.
cavity, pelvic
The area of the body that lies below the
abdomen, framed by the pelvic bones
and lower spine. The pelvic cavity con-
tains the lower digestive and urinary
organs, nearly all of the reproductive
organs in females, and part of the
reproductive system in males.
cavity, pleural
The space between the two layers of the
pleura
(membrane) that lines the chest
wall and the outside of the lungs.
CD4 count
A blood test used to monitor
HIV infec-
tion
and
AIDS
.
The procedure involves
counting the number of CD
4
lympho-
cytes
(white blood cells responsible for
fighting infection) in a blood sample.
CD
4
lymphocytes are destroyed by HIV,
and reduced levels of these cells indi-
cate the progression of H IV and the
eventual development of AIDS.
cefaclor
A common antibiotic that belongs to
the group of
cephalosporin drugs
.
cefadroxil
A
cephalosporin drug,
w hich is used to
treat bacterial infections.
cefalexin
A
cephalosporin drug
,
w hich is used to
treat bacterial infections.
cefotaxime
A
cephalosporin drug
,
w hich is used to
treat bacterial infections.
cefuroxime
A
cephalosporin drug
,
w hich is used to
treat bacterial infections.
celecoxib
A COX
-2
inhibitor drug (a type of
non-
steroidal anti-inflammatory drug
) used to
relieve the pain and inflammation of
rheumatoid arthritis
and
osteoarthritis
.
Side effects of celecoxib include nausea
and diarrhoea. Abdominal discomfort
may also occur, but can be m inim ized
by taking the drug w ith food.
cell
The basic structural unit of all living
organisms. The human body comprises
billions of cells, w hich are structurally
and functionally integrated to perform
the complex tasks necessary for life. In
spite of variations in size and function,
most of the cells have a sim ilar form.
CELL MEMBRANE
Each cell is a microscopically small bag
containing liquid cytoplasm. It is sur-
rounded by a membrane that regulates
the passage of useful substances (such
as oxygen and nutrients) into the cell
and waste materials (such as carbon
dioxide) and manufactured substances
(such as hormones) out of the cell.
Some cells, such as those lining the
small intestine, have m icrovilli, projec-
tions that increase the cells’ surface area
to facilitate absorption.
NUCLEUS
All cells, except red blood cells, have a
nucleus
.
The nucleus controls all major
cell activities by regulating the amount
and types of
proteins
made in the cell.
Inside the nucleus are
chromosomes
,
w hich are made of the nucleic acid
DNA
.
This acid contains the instructions
for
protein synthesis
,
w hich are carried
into the cytoplasm by a type of
RNA
(another nucleic acid) and are decoded
in
particles
called
ribosomes.
The
nucleus also contains a spherical struc-
ture called the nucleolus, w hich plays a
role in the production of ribosomes.
ORGANELLES
In the cytoplasm there are various tiny
structures called organelles, each with a
particular role. Energy is generated by
mitochondria
breaking down sugars and
fatty acids. Substances that would dam-
age the cell if they came into contact
with the cytoplasm are contained in
particles called lysosomes and peroxi-
somes. A system of membranes in the
cytoplasm,
called
the
endoplasmic
reticulum, transports materials through
the cell. Flattened sacs called the Golgi
complex receive and process proteins
from the endoplasmic reticulum.
Enzymes and hormones are secreted
by vesicles (small saclike structures) at
the cell surface. Some waste products
and other materials are transported and
stored in vacuoles (spaces created by
the cytoplasm). The cytoplasm has a
network of fine tubes (microtubules)
and filaments (microfilaments) known
as the cytoskeleton, w hich gives the
cell a definite shape.
cell death
See
apoptosis
.
cell division
The processes by w hich cells multiply.
Mitosis
is the most common form of
cell division, giving rise to daughter
cells identical to the parent cells.
Meio-
sis
produces egg (see
ovum
)
and
sperm
cells that differ from their parent cells
in that they have only half the normal
number of
chromosomes
.
cellular immunity
The part of the body’s defence mecha-
nisms (see
immune system
)
that attacks
and
destroys
harmful
cells
directly
rather than by using
antibodies
(pro-
teins created to combat infection).
Lymphocytes (a type of white blood
cell) mount a response against infectious
organisms and other abnormal cells,
such as cancer cells. There are two main
types: T-lymphocytes, w hich provide
cellular immunity, and B-lymphocytes,
152
previous page 151 BMA A Z Family Medical Encyclopedia   2004 read online next page 153 BMA A Z Family Medical Encyclopedia   2004 read online Home Toggle text on/off