Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «P»:
Paraquat lung: Lung disease caused by the contact herbicide paraquat which selectively accumulates in the lungs and is highly toxic. Once X-ray changes from paraquat are evident in the lungs, death is virtually certain.
Paraquat lung emerged as a health concern in the 1970s, when the US government...
Parasite: An organism that lives in or on and
takes its nourishment from another organism. A parasite cannot live independently.
Parasitic diseases include infections by protozoa,
helminths, and arthropods:
Protozoa -- Malaria is caused by plasmodium, a protozoa, a single-cell organism that can on...
Parasitemia: The presence of a parasite in the blood. For example, malarial parasitemia.
Parasitemia is analogous to bacteremia (the presence of bacteria in the blood) and viremia (the presence of a virus in the blood). Parasitemia, bacteremia and viremia are all forms of sepsis (bloodstream infect...
Parasitic: Having to do with a parasite, as in a
parasitic infection; or acting like a parasite by taking
nourishment from another....
Parasitic worm: A worm classified as a parasite. (A
parasite is a disease-causing organism that lives on or in a human or
another animal and derives its nourishment from its host.) Lice are
examples of parasites that live on humans; bacteria and viruses are
examples of parasites that live either...
Parasitosis: Infestation or infection with parasites. See also: Delusional parasitosis....
Paraskevidekatriaphobia: Fear of Friday the 13th.
The word "paraskevidekatriaphobia" was devised by Dr. Donald Dossey who told his patients that "when you learn to pronounce it, you're cured!"...
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 disorder, and nocturnal dissociative disorder.
Sleep talking may range from a word or two to an entire speech of...
Parasplenic: Located near or alongside of the spleen.
The spleen is an organ located in the upper left part of the abdomen near the stomach. The spleen produces lymphocytes, filters blood, serves as a major reservoir for blood and destroys blood cells that are aged.
The prefix "para-" comes straigh...
Parasuicide: An apparent attempt at suicide, commonly called a suicidal gesture, in which the aim is not death. For example, a sublethal drug overdose or wrist slash. Previous parasuicide is a predictor of suicide. The increased risk of subsequent suicide persists without decline for at least two de...
Parasympathetic nervous system
Parasympathetic nervous system: A part of nervous
system that serves to slow the heart rate, increase the intestinal and gland activity, and relax the sphincter muscles. The parasympathetic nervous system, together with the
sympathetic nervous system (that accelerates the heart rate, constricts bloo...
Parathormone: A hormone that is made by the parathyroid gland and that is critical to calcium and phosphorus balance. Deficiency of parathormone results in abnormally low calcium levels in the blood (hypocalcemia). Excessive parathormone leads to elevated calcium levels in the blood (hypercalcemia) ...
Parathyrin: See: Parathormone....
Parathyroid adenoma: A small tumor of the parathyroid gland and the most common disorder of the gland. Parathyroid adenomas are benign (NOT malignant). The gland increases in size and produces PTH in excess. This is called primary hyperparathyroidism.
In most cases, patients are unaware of the tu...
Parathyroid gland: A gland that regulates calcium, located behind the thyroid gland in the neck. The parathyroid gland secretes a hormone called parathormone (or parathyrin) that is critical to calcium and phosphorus metabolism. Although the number of
parathyroid glands can vary, most people have fo...