above the angle of the jaw, below and in
front of the ear, on each side of the face.
parotitis Inflammation of the
often due to infection with the
selective serotonin reuptake
antidepressant drug. Possible
side effects include nausea, indigestion,
and appetite loss.
paroxysm A sudden attack, worsening,
or recurrence of symptoms or of a dis-
parrot fever The common name for
parvovirus A 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
tion usually clears up within
passive smoking Involuntary inhala-
smoke by 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.
pasteurization The process of heating
foods to destroy disease-causing
, and to reduce the numbers
of microorganisms responsible for fer-
mentation and putrefaction.
patch test A method of diagnosing the
substances responsible for contact
A selection of possible
are put on a patch and taped to the
skin. A skin reaction indicates sensiti-
vity to a particular allergen.
patella The kneecap (see knee).
patent A term meaning open or unob-
). The term patent medicine is
sometimes used to refer to proprietary
drugs protected by a patent.
patent ductus arteriosus A defect of
in which the ductus arteriosus
(a channel between the pulmonary artery
and the aorta in the fetus) fails to close
at 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
). 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.
Diagnosis is made from hearing a
The drug indometacin or surgery may
be used to close the duct.
paternity testing The 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
, and simi-
lari ties in
DNA. Genetic fingerprinting
provides the most decisive result.
patho- A prefix denoting a relationship
pathogen Any agent, but particularly a
, that causes disease.
pathogenesis The processes by which
a disorder originates and develops.
pathognomonic A 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.
pathological Relating to disease or to
its study (
pathology The 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, cellular Also called cytopath-
ology, the branch of
with the effects of disease on cells.
chemical Another name
for clinical biochemistry, the study of
abnormalities in the chemistry of body
tissues in disease.
pathophysiology The study of the ef-
fects of disease on body functions.