Webster's New World Medical Dictionary

paraplegia
Paralysis of the lower part of the
body, including the legs.
paraquat lung
Lung disease caused by the con-
tact herbicide paraquat, which selectively accumu-
lates in the lungs and is highly toxic. The prognosis
depends upon the severity of exposure. Paraquat
lung is rare because the herbicide must be directly
inhaled to cause the disease. Paraquat lung
emerged as a health concern in the 1970s, when the
US government sprayed paraquat aerially over some
illegal marijuana fields. Some of the sprayed plants
survived and were sold, causing paraquat lung in
purchasers who smoked the product.
parasite
A plant or an animal organism that lives
in or on another and takes its nourishment from
that other organism. Parasitic diseases include
infections that are due to protozoa, helminths, or
arthropods. For example, malaria is caused by
Plasmodium, a parasitic protozoa.
parasitemia
The presence of parasites in the
blood. In malaria, a measure called the parasitemia
index reflects the severity of the disease.
parasitic
Having to do with a parasite, as in a
parasitic infection; or acting like a parasite by tak-
ing nourishment from another.
parasomnia
A sleep disorder in which odd or
dangerous events occur that intrude on sleep. The
parasomnias include sleep talking, sleepwalking
(somnambulism), sleep terrors, REM behavior dis-
order, and nocturnal dissociative disorder.
parasympathetic nervous system
The part of
the involuntary nervous system that serves to slow
the heart rate, increase intestinal and glandular
activity, and relax the sphincter muscles. The
parasympathetic nervous system, together with the
sympathetic nervous system, constitutes the auto-
nomic nervous system.
parathormone
A hormone that is made by the
parathyroid glands and is critical to maintaining cal-
cium and phosphorus balance. Deficiency of
parathormone results in abnormally low calcium in
the blood (hypocalcemia). Excessive parathormone
leads to elevated calcium levels in the blood and
calcium deposition in cartilage. Also known as
parathyroid hormone and parathyrin.