Bma Illustrated Medical Dictionary

Toxoplasmosis contracted by a pregnant
woman is transmitted to the fetus in
about a third of cases. It may result in
miscarriageor 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.
TPAThe abbreviation used for tissue-
plasminogen activator.
trabeculectomyA surgical procedure
to control glaucomaby 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.)
tracerA radioactive substance that is
introduced into the body so that its dis-
tribution, processing, and elimination
from the body can be monitored.
tracheaThe air passage, also called the
windpipe, that runs from immediately
below the larynxto 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,

LOCATION

which beat the mucus upwards to help

keep the lungs and airways clear.

tracheitisInflammation of the trachea.

Tracheitis is usually caused by a viral

infection and is aggravated by inhaled

fumes, especially tobacco smoke. It often

occurs with laryngitisand bronchitisin a

condition known as laryngotracheobron-

chitis. Symptoms include a painful dry

cough and hoarseness. In most cases,

no treatment is needed.

tracheoesophageal fistulaA rare birth

defect in which an abnormal passage

connects the tracheawith 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.

tracheostomyAn operation in which

an opening is made in the tracheaand 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 ventilationor is unable

to keep saliva and other secretions out

of the trachea. Permanent tracheostomy

is needed after laryngectomy.

tracheotomyCutting of the trachea. (See

also tracheostomy.)

trachomaA persistent infectious disease

of the corneaand 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.

tractAny one of

a group of organs

that form a com-

mon pathway to

perform a partic-

ular function. The

TPA TRACT

T

TRACHEA

Cartilage ring

Mucous

membrane

STRUCTURE OF TRACHEA

Air

passage

Layer of

mucus

Trachea

Bronchus

Muscle