TPA
TRACT
Toxoplasmosis contracted by a pregnant
woman is transmitted to the fetus in
about a third of cases. It may result in
miscarriage
or
stillbirth,
or the infant may
have an enlarged liver and spleen, blind-
ness,
hydrocephalus,
learning difficulties,
or may die during infancy. Infection in
late pregnancy usually has no ill effects.
The diagnosis is made from
blood
tests.
Treatment (with
pyrimethamine
and a
sulphonamide drug)
is necessary
only in pregnant women, in children
with severe symptoms, in people with
an immune system deficiency, and in
cases of retinitis or choroiditis.
TPA The abbreviation used for
tissue-
plasminogen activator.
trabeculectomy A surgical procedure
to control
glaucoma
by allowing the
fluid from the front chamber of the eye
to drain out under the conjunctiva.
trace elements
Minerals
necessary in
minute amounts in the diet to maintain
health. Examples are
chromium, copper,
zinc,
and
selenium.
(See also
nutrition.)
tracer A radioactive substance that is
introduced into the body so that its dis-
tribution, processing, and elimination
from the body can be monitored.
trachea The air passage, also called the
windpipe, that runs from immediately
below the
larynx
to behind the upper
part of the
sternum
, where it divides to
form the
bronchi
. The trachea is made
of fibrous and elastic tissue and smooth
muscle. It also contains about 20 rings of
cartilage,
which keep it open. The lining
of the trachea has cells (goblet cells)
that secrete mucus and cells with
cilia
,
which beat the mucus upwards to help
keep the lungs and airways clear.
tracheitis Inflammation of the
trachea.
Tracheitis is usually caused by a viral
infection and is aggravated by inhaled
fumes, especially tobacco smoke. It often
occurs with
laryngitis
and
bronchitis
in a
condition known as laryngotracheobron-
chitis. Symptoms include a painful dry
cough and hoarseness. In most cases,
no treatment is needed.
tracheoesophageal fistula A rare birth
defect in which an abnormal passage
connects the
trachea
with the
oesopha-
gus.
About 3 babies per 10,000 are born
with this
fistula.
The condition is often discovered soon
after birth; diagnosis may be confirmed
by
X-rays.
Treatment consists of an oper-
ation to close the fistula and connect
the trachea and oesophagus correctly.
tracheostomy An operation in which
an opening is made in the
trachea
and a
tube is inserted to maintain an effective
airway. A tracheostomy is used for the
emergency treatment of airway prob-
lems involving the
larynx
. A planned
tracheostomy is most commonly perfor-
med on a person who has lost the
ability to breathe naturally and is under-
going long-term
ventilation
or is unable
to keep saliva and other secretions out
of the trachea. Permanent tracheostomy
is needed after
laryngectomy
.
tracheotomy Cutting of the
trachea.
(See
also
tracheostomy
.)
trachoma A persistent infectious disease
of the
cornea
and
conjunctiva.
Trachoma
is caused by
chlamydia trachomatis
and is spread by
direct contact and
possibly by flies
(see
chlamydial
infections
).
It is
uncommon in the
UK,
but, world-
wide, is the most
common cause of
blindness .
tract Any one of
a group of organs
that form a com-
mon pathway to
perform a partic-
ular function. The
TRACHEA
Trachea
Bronchus
Air
passage
Mucous
membran
Layer of
mucus
Muscle
Cartilage ring
LOCATION
STRUCTURE OF TRACHEA
T
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