CIRCULATORY SYSTEM
chronological age
The most common measurement of an
individual’s
age
.
Churg-Strauss syndrome
A condition characterized by vasculitis
(inflammation in the walls of small
blood vessels), w hich mainly affects
adults in their thirties who have
asthma
.
It is thought to be due to an allergy of
unknown cause.
The vasculitis can cause a variety of
symptoms, depending on the parts of
the body that are affected. Common
problems include abdominal pain, if
the bowel is involved, and skin rashes.
The disease may be severe or even life-
threatening, although in most cases it
responds w ell to treatment with oral
corticosteroid drugs
.
The drug treatment
may need to be continued, at a low
dose, for some time to prevent a recur-
rence of the condition.
chylomicron
A globule of fat (see
fats and oils
)
that
is carried into the bloodstream from
the intestine following the digestion of
a meal containing fat.
Cicatrin
The brand name for an
antibacterial
skin preparation.
ciclosporin
An
immunosuppressant drug
that is used
following
transplant surgery
.
The drug
reduces the risk of tissue rejection and
the need for large doses of
corticosteroid
drugs
.
Ciclosporin may
need
to
be
taken indefinitely after a transplant. It is
also used to treat
rheumatoid arthritis
and other
autoimmune disorders
.
Because ciclosporin suppresses the
immune system
,
it increases the suscepti-
bility of the body to various infections.
Swelling of the gums and increased
hair growth are fairly common side
effects. The drug may also cause kidney
damage, so it is necessary for anyone
who is taking it to undergo regular
monitoring of kidney function.
Cilest
The brand name for a combined
oral
contraceptive
.
cilia
Hairlike, mobile filaments that exist on
the surface
of some
epithelial
cells
(see
epithelium
) .
Cilia are found in par-
ticularly
abundant
amounts
in
the
linings of the respiratory tract, where
they move rhythmically to propel dust
and mucus out of the airways.
ciliary body
A structure in the
eye
containing mus-
cles that alter the shape of the
lens
to
adjust focus. (See also
accommodation.)
cimetidine
An
H2-receptor antagonist,
w hich is a
type of
ulcer-healing drug.
Cimetidine
can be taken in tablet or liquid form,
or it may be injected. The drug pro-
motes healing of gastric and duodenal
ulcers (see
peptic ulcer)
and reduces the
symptoms of
oesophagitis
(inflamma-
tion of the gullet).
Side effects include fatigue, dizzi-
ness, and skin rashes. Rarely, the drug
may cause impotence and
gynaecomastia
(breast enlargement in men).
CIN
The
abbreviation for
cervical intraepi-
thelial neoplasia.
cinnarizine
An
antihistamine drug
used to control
nausea and vomiting due to travel sick-
ness, or to reduce nausea and vertigo in
disorders
of the
inner
ear
such as
labyrinthitis
and
Meniere’s disease.
High
doses of the drug are sometimes used
to improve circulation in people with
peripheral vascular disease
and
Raynaud’s
disease.
Side effects of cinnarizine may
include
drowsiness,
lethargy,
a
dry
mouth, and blurred vision.
Cipramil
A brand name for citalopram, an
anti-
depressant drug.
ciprofloxacin
An
antibiotic drug
that is used to treat
infections of the respiratory, gastro-
intestinal, and urinary tracts.
Cipro-
floxacin may also be used as an initial
treatment for
anthrax.
Ciproxin
A brand name for ciprofloxacin, an
antibiotic drug.
circadian rhythms
Any pattern of physiological functions
that is based on a cycle approximately
24
hours long (also called a diurnal
rhythm). One example of this pattern is
the daily cycle of sleeping and wakeful-
ness. (See also
biorhythms.)
circulation, disorders of
Conditions affecting the flow of blood
around the body. (See
arteries, disorders
of; veins, disorders of
. )
circulatory collapse
A life-threatening condition in w hich
the
circulatory system
is
unable
to
maintain an adequate blood flow to the
organs and tissues of the body (see
shock
) .
Circulatory collapse can occur
when the heart stops beating (see
car-
diac arrest
) ,
or be due to loss of blood
or problems with the blood vessels.
circulatory system
The
heart
and
blood vessels
,
w hich
together are responsible for the m ain-
tenance of a continuous flow of blood
through the body. Also known as the
cardiovascular system, the circulatory
system provides the body tissues with a
supply of oxygen and nutrients, and
carries away carbon dioxide and other
waste products.
STRUCTURE AND FUNCTION
The circulatory system has two main
parts: the systemic circulation, w hich
supplies blood to the whole body apart
from the lungs; and the pulmonary cir-
culation to the lungs, w hich supplies
the blood with fresh oxygen (see
circu-
latory system
box, overleaf).
Oxygen-rich blood from the pul-
monary circulation enters the systemic
circulation via the left
ventricle
of the
heart. The ventricle pumps it under
high pressure into the
aorta
(the body’s
main artery),
from where it travels
through arteries and smaller arterioles
to all parts of the body. W ithin the body
tissues, the arterioles branch into net-
works of fine blood vessels known as
capillaries. Oxygen and other nutrients
pass from the blood through the thin
capillary walls and into the tissues;
carbon dioxide and other waste pro-
ducts pass in the opposite direction.
Deoxygenated blood is returned to the
heart via venules (small veins), veins,
and the
venae cavae
(the two principal
veins in the body).
W ithin
the
systemic
circulation,
there is also a bypass (the portal cir-
culation)
that
carries
nutrient-rich
blood from the stomach, intestine, and
other digestive organs via the portal
vein to the
liver
.
Nutrients and other
substances pass into the liver cells for
processing, storage, breakdown, or re-
entry
into
the
general
circulation.
Blood passes out of the liver through
C
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