Glossary try the best to avoid the use of medical terms that could make it more difficult to understand the information on this website. Still, there are a number of terms that can't be avoided and that are useful to know because they are so often used by the doctors, nurses, and other medical professionals with whom you might speak. The list below includes the terms used on for which we have provided definitions.

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Paget Disease

1) The most common use of the term refers to a bone disorder in which bone is formed and broken down excessively, resulting in weakened bones. This condition can cause bone pain, deformed bones, arthritis, and numerous fractures.

2) Other, less common uses of the term refer to rare forms of cancer involving the nipple of the breast or the skin of other areas such as the perianal region, penis, or vulva (also termed extramammary).


Pale skin color


An epidemic that occurs over a wide geographic area (across continents)


tumor that releases excess hormones called catecholamines (e.g., dopamine, epinephrine (adrenaline), norepinephrine and their metabolites, such as metanephrines) and usually occurs somewhere in the abdomen but outside the adrenal glands


Any of a genus (Paramecium) of ciliate chiefly freshwater protozoans that have an elongate body rounded at the anterior end and an oblique funnel-shaped buccal groove bearing the mouth at the extremity.


One of the four major groups of microorganisms (bacteria, viruses, fungi, and parasites) that may live freely in nature, live on another organism without harming it, or live at the expense of the host organism


Administration of a substance (e.g., a drug) by injection (under or through the skin) or intravenously but not through the digestive system (not enterally)


numbness, tingling, or prickling; an alteration in sensation


1) Of or pertaining to the cells that line a cavity, such as the chest or abdomen;

2) A specialized cell in the stomach that makes acid to help in food digestion, as well as intrinsic factor, which is needed to absorb vitamin B12

Paroxysmal choreoathetosis

A condition characterized by involuntary, intermittent, and irregular movements of facial muscles and limbs


Organism that causes disease




A physician who diagnoses and characterizes disease by examining a patient’s tissues, blood, and other body fluids. Pathologists work in two broad areas:

Anatomic pathology is the examination of the physical appearance and microscopic structure of tissues. Anatomic pathologists look at biopsies and organs removed at surgery (surgical pathology) as well as cells that are collected from brushings or body fluids (cytology). They also perform autopsies to investigate the cause of death (autopsy pathology).

Clinical pathology deals with the measurement of chemical constituents of blood and other body fluids (clinical chemistry), analysis of blood cells (hematology), identification of microorganisms (microbiology), and the collection, preparation and use of blood for transfusion (transfusion medicine). Clinical pathologists direct the laboratories that perform these tests and provide consultation to other doctors on the significance of test results.


Sac-like membrane that surrounds the heart and the base of the blood vessels that lead into it

Peripheral nervous system

All parts of the nervous system except the brain and spinal cord


Membranes that cover the abdominal cavity and the outside of abdominal organs


Measurement of the acidity or alkalinity of a substance. A pH of 7.0 is neutral. A substance with a pH less than 7.0 is an acid, with increasing acidity as the pH decreases toward zero. Likewise, a substance with a pH greater than 7.0 is a base (alkali), with increasing alkalinity as the pH moves toward 14.0.


The observable physical or biochemical characteristics of a person, as determined by both their genetic makeup and environmental influences


tumor located in one or both of the adrenal glands that releases excess hormones called catecholamines (e.g., dopamine, epinephrine (adrenaline), norepinephrine and their metabolites, such as metanephrines)


A substance in the body that contains both lipid (fat) and phosphorous; phospholipids are found in all cells throughout the body because they are a major component of the cell membrane, the outermost layer of a cell.

Pituitary gland

Pea-sized gland located in the center of the head behind the sinus cavity at the base of the brain; the pituitary consists of two parts that produce different hormones: 1) in the anterior portion, growth hormone (GH), adrenocorticotropin (ACTH), thyroid-stimulating hormone (TSH), lutenizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin (PRL) are produced; 2) in the posterior portion, oxytocin and antidiuretic hormone (ADH) (produced in the hypothalamus) are stored for release.


The organ that connects a pregnant woman with her developing baby in the uterus; blood from the mother and baby do not mix directly, but a thin membrane within the placenta allows nutrients from the mother to pass to the baby and waste products to pass from the baby to the mother for elimination.


1. Deposit on the inner arterial walls in atherosclerosis
2. Flat, raised patch on the skin or mucous membrane
3. Deposit of saliva and bacteria on teeth that encourages the development of caries


Straw-colored, fluid part of blood and lymph

Plasma cell

Mature lymphocyte (B cell) that produces and secretes antibodies


Also known as: Pleurae (plural)

One of the two membranes that surrounds each lung and lines the chest cavity


Also known as: Pleura

One of the two membranes that surrounds each lung and lines the chest cavity


An inflammation of the lungs; usually caused by a hypersensitive allergic reaction to repeated exposure to organic particles such as molds, grain dust, and chemicals

Polyclonal antibody

Antibody produced by or derived from many types (clones) of plasma cells


Increase in the number of erythrocytes (red cells, RBCs) in the blood


A large molecule consisting of multiple identical or similar chemical units that are linked together


Gene having many different possible forms (alleles)

See also: Polymorphism


Inherited person-to-person variation in the genetic code sequence within a specified DNA segment or gene

See also: Polymorphic

Polymyalgia Rheumatica

A disease that causes pain and weakness in the neck, shoulder muscles and pelvis, and morning stiffness. It commonly affects people over 50 years of age, especially women.


A growth, such as on the lining of the mouth or intestines, that is usually benign; examples include uterine polyps and colorectal polyps


At or toward the back


1. one that comes before or gives rise to another
2. in chemistry, one substance that comes before or gives rise to another often more stable substance


Based on reasonable evidence or assumption; based on early, preliminary or partial results


The number of people with a particular disease at any given time in a population

Preventive Medicine

That branch of medicine concerned primarily with the prevention of disease

Prion Protein

An infectious agent (not bacteria or virus) that is an irregular form of a normal protein; prion proteins cause a variety of infections, including Mad Cow Disease and Creutzfeld-Jacob disease. Prion proteins are thought to induce normal brain proteins to assume an irregular shape, rendering them dysfunctional.


1) prediction about the course or outcome of a disease or illness
2) the likelihood of recovery from a disease or illness


(adj. Prophylactic)
1. Measure taken to prevent or protect against disease
2. Antibiotic prescribed to prevent infection


inflammation of the prostate


Proteins are large molecules that form the structural part of most organs and make up enzymes and hormones that regulate body functions.


Also known as: Itch

An irritating skin condition that causes a desire to scratch


Also known as: Itch

An irritating skin condition that causes a desire to scratch

Purpura fulminans

Involves severe clotting throughout much of the body, ultimately causing death to the tissues. If not treated immediately, it is a life-threatening condition.


Collection of fluid, white blood cells, microorganisms, and cellular material that indicates the presence of an infected wound or abscess