Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «P»:
Primary teeth: The first teeth which are shed and replaced by permanent teeth. The first primary tooth comes in at about 6 months of age and the 20th and last primary tooth erupts at around 2 1/2 years of age. The primary teeth are replaced beginning usually at about age 6. Also called baby teeth, m...
Primary tumor: A tumor that is at the original site where it first arose. For example, a primary brain tumor is one that arose in the brain as opposed to one that arose elsewhere and metastasized (spread) to the brain. The original tumor is sometimes called "the primary."...
Primitive neuroectodermal tumor
Primitive neuroectodermal tumor: One of a remarkable group of tumors that originate in cells from the primitive neural crest and share the same reciprocal translocation between chromosomes 11 and 22 and the same patterns of biochemical and oncogene expression. Some primitive neuroectodermal tumors (...
Primordia: See: Primordium....
Primordium: In embryology, organ or tissue in its earliest recognizable stage of development. As, for example, the thyroid primordium. The plural is primordia. Borrowed directly from the Latin primordium (to begin), derived from the Latin words primus (first) + ordiri (to begin0. Known also as the a...
Primum non nocere
Primum non nocere: The Latin words
for medical slogan "First do no harm," a fundamental
medical precept of Hippocrates (ca. 460-ca.377 B.C.)....
Principal investigator: In biomedical research, the person who directs a research project or program. The principal investigator (the PI) usually writes and submits the grant application, oversees the scientific and technical aspects of the grant, and has responsibility for the management of the res...
Principal joints of the body
Principal joints of the body: The principal joints of the
human body include the following:
Ankle (tibia-fibula and talus)
Atlas and axis
Atlas and occipital
Elbow (humerus, radius, and ulna)
Femur and tibia
Hip bone and femur
Prinzmetal angina: See: Angina, Prinzmetal....
Prion: A disease-causing
agent that is neither bacterial nor fungal nor viral and contains no
genetic material. A prion is a protein that occurs normally in a
harmless form. By folding into an aberrant shape, the normal prion
turns into a rogue agent. It then coopts other normal prions to
Prion dementia: See: Gerstmann-Straussler-Scheinker syndrome....
Prion disease: A disease due to a prion, a proteinaceous infectious particle that lacks nucleic acids. Prions are composed largely, if not entirely, of an altered formal (an abnormal isoform) of a normal cellular protein.
The known prion diseases of humans and other mammals are:
Prior approval: See: Prior authorization....
Prior authorization: In pharmacy, a cost-containment procedure that requires a prescriber to obtain permission to prescibe a medication prior to prescribing it. Also called prior approval....
Private mutation: A rare mutation found usually only in a single family or a small population. It is like a privately printed book....