above the angle of the jaw, below and in
front of the ear, on each side of the face.
parotitisInflammation of the parotid
glands, often due to infection with the
mumpsvirus.
paroxetineA selective serotonin reuptake
inhibitorantidepressant drug. Possible
side effects include nausea, indigestion,
and appetite loss.
paroxysmA sudden attack, worsening,
or recurrence of symptoms or of a dis-
ease; a spasmor seizure.
parrot feverThe common name for
psittacosis.
parturition See childbirth.
parvovirusA viral infection that causes
a rash and joint inflammation. Many
children have no symptoms, but some
have a bright red rash on the cheeks, a
mild fever, and sometimes mild joint
inflammation. Symptoms are more sev-
ere in adults; they include a rash on the
palms and soles of the feet and severe
inflammation in the knee, wrist, and hand
joints. A diagnosis is made from the
symptoms and a blood test. The infec-
tion usually clears up within 2 weeks
without treatment.
passive smokingInvoluntary inhala-
tion oftobacco smokeby people who do
not smoke. Passive smoking has been
shown to increase the risks of chest and
ear infections in children and of tobacco-
induced cancers in adults.
pasteurizationThe process of heating
foods to destroy disease-causing micro-
organisms, and to reduce the numbers
of microorganisms responsible for fer-
mentation and putrefaction.
patch testA method of diagnosing the
substances responsible for contact der-
matitis. A selection of possible allergens
are put on a patch and taped to the
skin. A skin reaction indicates sensiti-
vity to a particular allergen.
patellaThe kneecap (see knee).
patentA term meaning open or unob-
structed (such as in patent ductus
arteriosus). The term patent medicine is
sometimes used to refer to proprietary
drugs protected by a patent.
patent ductus arteriosusA defect of
the heartin which the ductus arteriosus
(a channel between the pulmonary artery
and the aorta in the fetus) fails to closeat birth. It affects about 60 babies per
100,000. In the fetus, blood pumped by
the right side of the heart flows through
the ductus arteriosus and bypasses the
lungs (seefetal circulation). At or shortly
after birth, the ductus usually closes. In
some babies this closure may fail to
happen, preventing normal circulation.
There are usually no symptoms unless a
large amount of blood is misdirected, in
which case the baby fails to gain weight,
becomes short of breath on exertion,
and may have frequent chest infections.
Eventually, heart failuremay develop.
Diagnosis is made from hearing a
heart murmur, from chest X-rays, and
from an ECG and echocardiography.
The drug indometacin or surgery may
be used to close the duct.
paternity testingThe use of blood
tests to help decide whether a man is
the father of a child. Blood samples are
taken from the child, from the suspected
father, and sometimes from the mother.
The samples are tested for blood groups,
histocompatibility antigens, and simi-
larities in DNA. Genetic fingerprinting
provides the most decisive result.
patho-A prefix denoting a relationship
to disease.
pathogenAny agent, but particularly a
microorganism, that causes disease.
pathogenesisThe processes by which
a disorder originates and develops.
pathognomonicA medical term applied
to a symptom or sign that is character-
istic of a disease or disorder and is
therefore sufficient to make a diagnosis.
pathologicalRelating to disease or to
its study (pathology).
pathologyThe study of disease – its
causes, mechanisms, and effects on the
body. Pathologists conduct autopsies to
determine causes of death and to deter-
mine the effects that a disease or a
treatment has had.
pathology, cellularAlso called cytopath-
ology, the branch of cytology concerned
with the effects of disease on cells.
pathology, chemicalAnother name
for clinical biochemistry, the study of
abnormalities in the chemistry of body
tissues in disease.
pathophysiologyThe study of the ef-
fects of disease on body functions.PAROTITIS PATHOPHYSIOLOGYP