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Medical Dictionary


See plano-.

planigraphy (pla-nig′ra-fe)
SYN: tomography. [L. planum, plane, + G. graphe, a writing]

planimeter (pla-nim′e-ter)
An instrument formed of jointed levers with a recording index, used for measuring the area of any surface, by tracing its boundaries. [L. planum, plane, + G. metron, measure]

planimetry (pla-nim′e-tre)
The measurement of surface areas and perimeters by tracing the boundaries. P. on photomicrographs or projected images may be used to evaluate the size of cells.

planithorax (plan′i-tho′raks)
A diagram of the chest showing the front and back in plane projection, after the manner of Mercator projection of the earth's surface.

plankter (plangk′ter)
Any type of plankton.

plankton (plangk′ton)
A general term for many floating marine forms, mostly of microscopic or minute size, which are moved passively by winds, waves, tides, or currents; it includes diatoms, algae, copepods, and many protozoans, crustacea, mollusks, and worms. [G. planktos, wandering]

planktonic (plangk-ton′ik)
Relating to plankton;plankton-like.

plano-, plan-, plani-
1. A plane; flat, level. [L. planum, plane; planus, flat] 2. Wandering. [G. planos, roaming]

planocellular (pla-no-sel′u-lar)
Relating to or composed of flat cells. [L. planus, flat, + cellular]

planoconcave (pla′no-kon-kav′)
Flat on one side and concave on the other; denoting a lens of that shape.

planoconvex (pla′no-kon-veks′)
Flat on one side and convex on the other; denoting a lens of that shape.

planography (pla-nog′ra-fe)
SYN: tomography.

planomania (plan-o-ma′ne-a)
A rarely used term for the morbid impulse to leave home and discard social restraints. [G. planos, wandering, + mania, frenzy]

Planorbis (plan-or′bis)
A European and North African genus of freshwater snails (family Planorbidae), including P. p., intermediate host of the sheep and cattle fluke, Paramphistoma cervi. [G. planos, wandering, + L. orbis, circle, ring]

planovalgus (pla-no-val′gus)
A condition in which the longitudinal arch of the foot is flattened and the hindfoot is everted. [plano- + L. valgus, turned outward]

planta, gen. and pl. plantae (plan′ta, plan′te) [TA]
SYN: sole. [L.] p. pedis [TA] SYN: sole of foot.

plantago (plan-ta′go)
The root and leaves of the common or large-leaved plantain, P. major (family Plantaginaceae). [L. plantain] p. ovata coating the separated outer mucilaginous layers of P. ovata seeds; used in simple constipation associated with lack of sufficient bulk. p. seed SYN: psyllium seed.

plantain seed
SYN: psyllium seed.

plantalgia (plan-tal′je-a)
Pain on the plantar surface of the foot over the plantar fascia. [L. planta, sole of foot, + G. algos, pain]

plantar (plan′tar) [TA]
Relating to the sole of the foot. SYN: plantaris [TA] . [L. plantaris]

plantaris (plan-tar′is) [TA]
SYN: plantar, plantar. [L.]

plantigrade (plan′ti-grad)
Walking with the entire sole and heel of the foot on the ground, as do humans and bears. [L. planta, sole, + gradior, to walk]

planula, pl .planulae (plan′u-la, -le)
Name given by Lankester to a coelenterate embryo when it consists of the two primary germ layers only, the ectoderm and endoderm. [L. dim. of planum, flat surface] invaginate p. SYN: gastrula.

planum, pl .plana (pla′num, pla′na)
SYN: plane. [L. plane] plana coronalia SYN: frontal plane. plana frontalia [TA] SYN: frontal plane. horizontal planes [TA] plane parallel and relative to the horizon; in the anatomic position, horizontal planes are transverse planes; in the supine or prone positions, horizontal planes are frontal (coronal planes). SYN: plana horizontalia [TA] . plana horizontalia [TA] SYN: horizontal planes. p. interspinale [TA] SYN: interspinous plane. SEE ALSO: Addison clinical planes, under plane. p. intertuberculare [TA] SYN: intertubercular plane. SEE ALSO: Addison clinical planes, under plane. p. medianum [TA] SYN: median plane. p. occipitale [TA] SYN: occipital plane. p. orbitale SYN: orbital plane. p. popliteum SYN: popliteal surface of femur. plana sagittalia [TA] SYN: sagittal plane. p. semilunatum the area of epithelium bounding the sensory area of the crista ampullaris. p. sphenoidale [TA] SYN: jugum sphenoidale. p. sternale SYN: sternal plane. p. subcostale [TA] SYN: subcostal plane. p. supracristale [TA] SYN: supracristal plane. p. temporale [TA] SYN: temporal plane. p. transpyloricum [TA] SYN: transpyloric plane. See Addison clinical planes, under plane. plana transversalia [TA] SYN: transverse plane.

planuria (pla-noo′re-a)
1. Extravasation of urine. 2. The voiding of urine from an abnormal opening. [G. planos, wandering, + ouron, urine]

plaque (plak)
1. A patch or small differentiated area on a body surface ( e.g., skin, mucosa, or arterial endothelium) or on the cut surface of an organ such as the brain; in skin, a circumscribed, elevated, superficial, and solid area greater than 1.0 cm in diameter. 2. An area of clearing in a flat confluent growth of bacteria or tissue cells, such as is caused by the lytic action of bacteriophage in an agar plate culture of bacteria, by the cytopathic effect of certain animal viruses in a sheet of cultured tissue cells, or by antibody (hemolysin) produced by lymphocytes cultured in the presence of erythrocytes and to which complement has been added. 3. A sharply defined zone of demyelination characteristic of multiple sclerosis. 4. See dental p.. [Fr. a plate] atheromatous p. a well-demarcated yellow area or swelling on the intimal surface of an artery; produced by intimal lipid deposit. bacterial p. in dentistry, a mass of filamentous microorganisms and a large variety of smaller forms attached to the surface of a tooth that, depending on bacterial activity and environmental factors, may give rise to caries, calculus, or inflammatory changes in adjacent tissue. SYN: dental p. (2) , mucous p., mucinous p.. bacteriophage p. a clear circular zone in an otherwise confluent growth of bacteria on an agar surface resulting from bacterial lysis by bacterial viruses. dental p. 1. the noncalcified accumulation mainly of oral microorganisms and their products that adheres tenaciously to the teeth and is not readily dislodged; 2. SYN: bacterial p.. Hollenhorst plaques glittering, orange-yellow, atheromatous emboli in the retinal arterioles that contain cholesterol crystals and originate in the carotid artery or great vessels. mucous p., mucinous p. SYN: bacterial p.. neuritic p. SYN: senile p.. pleural p. fibrous thickening of the parietal pleura, characteristically caused by inhalation exposure to asbestos; both microscopic and macroscopic calcification in this lesion is common. Randall plaques mineral concentrations on renal papillae. senile p. a spherical mass composed primarily of amyloid fibrils and interwoven neuronal processes, frequently, although not exclusively, observed in Alzheimer disease. SYN: neuritic p..

Plaque Index
An index for estimating the status of oral hygiene by measuring dental plaque that occurs in the areas adjacent to the gingival margin.

Formation (especially of cells). See plasma-. [G. plasso, to form]

plasm (plazm)
SYN: plasma.

plasma (plaz′ma)
1. The proteinaceous fluid (noncellular) portion of the circulating blood, as distinguished from the serum obtained after coagulation. SYN: blood p.. 2. The fluid portion of the lymph. 3. The fluid in which the fat droplets of milk are suspended. 4. A “fourth state of matter” in which, owing to elevated temperature, atoms have broken down to form free electrons and more or less stripped nuclei; produced in the laboratory in connection with hydrogen fusion (thermonuclear) research. SYN: plasm. [G. something formed] antihemophilic p. human p. in which the labile antihemophilic globulin component, present in fresh p., has been preserved; it is used to temporarily relieve dysfunction of the hemostatic mechanism in hemophilia. blood p. SYN: p. (1) . p. expander (plaz′ma eks-pan′der) SYN: p. substitute. fresh frozen p. (FFP) separated p., frozen within 6 hours of collection, used in hypovolemia and coagulation factor deficiency. p. hydrolysate an artificial digest of protein derived from bovine blood p. prepared by a method of hydrolysis sufficient to provide more than half of the total nitrogen present in the form of α-amino nitrogen; used when high protein intake is indicated and cannot be accomplished through ordinary foods. SEE ALSO: protein hydrolysate. p. marinum sea water diluted to make it isotonic with p.. muscle p. an alkaline fluid in muscle that is spontaneously coagulable, separating into myosin and muscle serum. normal human p. sterile p. obtained by pooling approximately equal amounts of the liquid portion of citrated whole blood from eight or more adult humans who have been certified as free from any disease that is tranmissible by transfusion, and treating it with ultraviolet irradiation to destroy possible bacterial and viral contaminants. salted p. the fluid portion of blood drawn from the vessels, which is prevented from coagulating by being drawn into a solution of sodium or magnesium sulfate. SYN: salted serum.

plasma-, plasmat-, plasmato-, plasmo-
Formative, organized; plasma. [G. plasma, something formed]

plasmablast (plaz′ma-blast)
Precursor of the plasma cell. SYN: plasmacytoblast. [plasma + G. blastos, germ]

plasma cell dyscrasia
A diverse group of diseases characterized by the proliferation of a single clone of cells producing a monoclonal immunoglobulin or immunoglobulin fragment (a serum M component). The cells usually have plasma cell morphology, but may have lymphocytic or lymphoplasmacytic morphology. This group includes multiple myeloma, Waldenström macroglobulinemia, the heavy chain disease, benign monoclonal gammopathy, and immunocytic amyloidosis.

plasmacrit (plaz′ma-krit)
A measure of the percentage of the volume of blood occupied by plasma, in contrast to a hematocrit. [plasma + G. krino, to separate]

plasmacyte (plaz′ma-sit)
SYN: plasma cell.

plasmacytoblast (plas-ma-si′to-blast)
SYN: plasmablast.

plasmacytoma (plaz′ma-si-to′ma)
A discrete, presumably solitary mass of neoplastic plasma cells in bone or in one of various extramedullary sites; in humans, such lesions are probably the initial phase of developing plasma cell myeloma. [plasmacyte + G. -oma, tumor]

plasmacytosis (plaz′ma-si-to′sis)
1. Presence of plasma cells in the circulating blood. 2. Presence of unusually large proportions of plasma cells in the tissues or exudates. [plasmacyte + G. -osis, condition]

plasmagene (plaz′ma-jen)
A determinant of an inherited character located in the cytoplasm. SYN: cytogene. [plasma + gene]

plasmakinins (plaz′ma-kin′inz)
A group of highly active oligopeptides found in sera that act upon smooth muscle of blood vessels, uterus, bronchi, etc.; E.G., bradykinin, kallidin.

plasmalemma (plaz-ma-lem′a)
SYN: cell membrane. [plasma + G. lemma, husk]

plasmalogens (plaz-mal′o-jenz)
Generic term for glycerophospholipids in which the glycerol moiety bears a 1-alkenyl ether group (on rarer occasions, a 1-alkyl ether group); e.g., alk-1-enylglycerophospholipid; p. synthesis is reduced in disorders of the peroxisome. SYN: phosphoglyceracetals.

plasmals (plaz′malz)
Long-chain aldehydes occurring in plasmalogens; e.g., stearaldehyde, palmitaldehyde.

plasmapheresis (plaz′ma-fe-re′sis)
Removal of whole blood from the body, separation of its cellular elements by centrifugation, and reinfusion of them suspended in saline or some other plasma substitute, thus depleting the body's own plasma without depleting its cells. [plasma + G. aphairesis, a withdrawal]

plasmapheretic (plaz′ma-fe-ret′ik)
Relating to plasmapheresis.

See plasma-.

plasmatic (plaz-mat′ik)
Relating to plasma. SYN: plasmic.

plasmatogamy (plaz-ma-tog′a-me)
SYN: plasmogamy.

plasmenic acid (plaz′men-ik)
Proposed name for phosphatidates such as 2-acyl-1-alk-1-enylglycerol 3-phosphate.

plasmic (plaz′mik)
SYN: plasmatic.

plasmid (plaz′mid)
A genetic particle physically separate from the chromosome of the host cell (chiefly bacterial) that can stably function and replicate and usually confer some advantage to the host cell; not essential to the cell's basic functioning. SYN: extrachromosomal element, extrachromosomal genetic element, paragene. [cytoplasm + -id] bacteriocinogenic plasmids bacterial plasmids responsible for the elaboration of bacteriocins. SYN: bacteriocin factors, bacteriocinogens. conjugative p. a p. that can effect its own intercellular transfer by means of conjugation; this transfer is accomplished by a bacterium being rendered a donor, usually with specialized pili. SYN: infectious p., transmissible p.. F p. the prototype conjugative p. associated with conjugation in the K-12 strain of Escherichia coli. SYN: fertility factor, sex factor. infectious p. SYN: conjugative p.. nonconjugative p. a p. that cannot effect conjugation and self-transfer to another bacterium (bacterial strain); transfer depends upon mediation of another (and conjugative) p.. R plasmids SYN: resistance plasmids. resistance plasmids plasmids carrying genes responsible for antibiotic (or antibacterial drug) resistance among bacteria (notably Enterobacteriaceae); they may be conjugative or nonconjugative plasmids, the former possessing transfer genes (resistance transfer factor) lacking in the latter. SYN: R factors, R plasmids, resistance factors, resistance-transferring episomes. transmissible p. SYN: conjugative p..

plasmin (plaz′min)
A serine proteinase hydrolyzing peptides and esters of l-arginine and l-lysine and converting fibrin to soluble products; occurs in plasma as the precursor plasminogen (profibrinolysin) and is activated to p. by organic solvents, which remove an inhibitor, and by streptokinase, trypsin, and plasminogen activator, all cleaving a single arginyl-valyl bond; p. is responsible for the dissolution of blood clots. SYN: fibrinase (2) , fibrinolysin.

plasminogen (plaz-min′o-jen)
A precursor of plasmin. There is an autosomal dominant deficiency of p. [MIM*173350] that may promote thrombosis. See plasmin.

plasminokinase (plaz′min-o-ki′nas)
SYN: streptokinase.

plasminoplastin (plaz′min-o-plas′tin)
Term proposed for activator agents that produce plasmin by direct action on plasminogen; e.g., staphylokinase, plasminogen activator.

See plasma-.

plasmodia (plaz-mo′de-a)
Plural of plasmodium. [L.]

plasmodial (plaz-mo′de-al)
1. Relating to a plasmodium. 2. Relating to any species of the genus Plasmodium.

plasmodiotrophoblast (plaz-mo′de-o-tro′fo-blast)
SYN: syncytiotrophoblast. [plasmodium + G. trophe, nourishment, + blastos, germ]

Plasmodium (plaz-mo′de-um)
A genus of the protozoan family Plasmodidae (suborder Haemosporina, subclass Coccidia), blood parasites of vertebrates, characterized by separate microgametes and macrogametes, a motile ookinete, sporogony in the invertebrate host, and merogony (schizogony) in the vertebrate host; includes the causal agents of malaria in humans and other animals, with an asexual cycle occurring in liver and red blood cells of vertebrates and a sexual cycle in mosquitoes, the latter cycle resulting in the production of large numbers of infective sporozoites in the salivary glands of the vector, which are transmitted when the mosquito bites and draws blood. Primate malaria is transmitted by various species of Anopheles mosquitoes, bird malaria by species of Aedes, Culex, Anopheles, and Culiseta. [Mod. L. from G. plasma, something formed, + eidos, appearance] P. aethiopicum SYN: P. falciparum. P. berghei a species of protozoan that is the etiologic agent of rodent malaria from central Africa; an important source of experimental nonprimate mammal malaria. P. brazilianum a protozoan species found in New World monkeys of the family Cebidae in northern South America and Panama, which can cause mild malaria in humans. P. cynomolgi a protozoan species similar to P. vivax occurring naturally in the macaque, but infecting humans both accidentally and experimentally; it produces a P.-vivax type of malaria. P. falciparum Laverania falciparum, a species that is the causal agent of falciparum (malignant tertian) malaria; a young trophozoite is about one-fifth the size of an erythrocyte, but developing erythrocytic stages are rarely seen in circulating blood, as they render infected cells sticky and cause them to concentrate in capillaries in the vital organs, particularly the brain and the heart; a schizont occupies about one-half to two-thirds of the red blood cell and has fine, sparse granules (observed in peripheral blood only from moribund patients); infected erythrocytes are normal or contracted in size and are likely to contain basophilic granules and red dots (Maurer clefts or dots); multiple infection is extremely frequent and causes bouts of fever somewhat irregularly, since the parasite's cycles of multiplication are usually asynchronous. SYN: malignant tertian malarial parasite, P. aethiopicum. P. knowlesi a species of protozoan from Southeast Asia that causes monkey malaria with a quotidian fever cycle; highly fatal in rhesus monkeys; naturally acquired by a human in Malaysia, and also transmitted to humans experimentally. P. kochi a P. species now recognized as Hepatocystis kochi. P. malariae a protozoan species that is the causal agent of quartan malaria; a ring-stage trophozoite is triangular, ovoid, or slightly bean shaped, with fine or coarse black granules, approximately one-third the size of an eythrocyte; the schizont is oval or rounded and nearly fills the red blood cell; infected erythrocytes are normal or slightly contracted in size, usually with no stippling (the two most important characteristics that distinguish it from P. vivax), although extremely fine Ziemann dots may be observed; multiple infection is extremely rare; thus, bouts of fever occur fairly regularly at 72-hour intervals; prolonged asymptomatic parasitemia is characteristic of the species, and recrudescence of fever may occur 10 years or more after the initial episode. SYN: quartan parasite. P. ovale a protozoan species that is the agent of the least common form of human malaria; resembles P. vivax in its earlier stages but often modifies the cell membrane, causing it to form a fimbriated outline and, often assume an oval shape; Schüffner dots are abundant and appear early, host cells are normal or only slightly enlarged, and only about 8–10 grapelike merozoites are produced; fever is tertian (every 48 hours), and relapses are infrequent. P. vivax a protozoan species that is the most common malarial parasite of humans (except in West Africa, where the form of the Duffy antigen (FyFy) protects most of the resident populations, which has permitted P. ovale to replace P. vivax); the early trophozoite is irregular and ameboid in shape, one-fourth to one-third the size of a red blood cell, and contains several fine granules; the schizont is irregular in shape, fills the enlarged erythrocyte, and contains numerous yellow-brown pigment granules; affected red blood cells are pale, enlarged, and contain Schüffner dots in the later stages of growth; characteristically causes bouts of fever fairly regularly at 48-hour intervals, but multiple infection, causing irregular fever patterns, is common. SYN: tertian parasite.

plasmodium, pl .plasmodia (plaz-mo′de-um, -de-a)
A protoplasmic mass containing several nuclei, resulting from multiplication of the nucleus with cell division. [Mod. L. fr. G. plasma, something formed, + eidos, appearance] placental p. SYN: syncytiotrophoblast.

Plasmodromata (plaz-mo-dro′ma-ta)
A former taxonomic category that included ameboid and flagellate Protozoa in which the nucleus is not separated into reproductive (micro-) and vegetative (macro-) portions; equivalent to the present phylum Sarcomastigophora. [plasmo- + G. dromos, a running, a course]

plasmogamy (plaz-mog′a-me)
Union of two or more cells with preservation of the individual nuclei; formation of a plasmodium. SYN: plasmatogamy, plastogamy. [plasmo- + G. gamos, marriage]


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