Copy of `Dorland's Medical Dictionary`

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Dorland's Medical Dictionary Category: Health and Medicine > Medical Dictionary Date & country: 31/12/2010, USA Words: 39128

plasmalemma
(plaz″mә-lem´ә) plasma membrane.

plasmapheresis
(plaz″mә-fә-re´sis) the removal of plasma from withdrawn blood, with retransfusion of the formed elements into the donor; generally, type-specific fresh frozen plasma or albumin is used to replace the withdrawn plasma. The procedure may be done for purposes of collecting plasma components or for therapeutic ...

plasmid
(plaz´mid) an extrachromosomal self-replicating structure found in bacterial cells that carries genes for a variety of functions not essential for cell growth. Plasmids consist of cyclic double-stranded DNA molecules, replicating independently of the chromosomes and transmitting through successive cell divisions g...

plasmin
(plaz´min) the active principle of the fibrinolytic or clot-lysing system, a proteolytic enzyme with a high specificity for fibrin and the particular ability to dissolve formed fibrin clots.

plasminogen
(plaz-min´ә-jәn) the inactive precursor of plasmin, occurring in plasma and converted to plasmin by the action of urokinase; see also plasminogen activator. Called also profibrinolysin.

plasminogen activator inhibitor
(PAI) any of several regulators of fibrinolysis that act by binding to and inhibiting free plasminogen activator. Their concentration in plasma is normally low, but is altered in some disturbances of bodily hemostasis. PAI-1 is an important fast-reacting inhibitor of t-plasminogen activator and u-plasminogen activator. ...

plasmodicidal
(plaz″mo-dĭ-si´dәl) destructive to plasmodia; see also antimalarial.

Plasmodium
(plaz-mo´de-әm) the malarial parasites, a genus of protozoa (suborder Haemosporina, order Eucoccidiida), parasitic in the red blood cells of humans and other animals. The organism is transmitted in sporozoite form to the bloodstream of humans by the bite of anopheline mosquitoes. The parasites migrate directly to ...

plasmodium
(plaz-mo´de-әm) a parasite of the genus Plasmodium. a multinucleate continuous mass of protoplasm. adj., plasmo´dial., adj.

plasmogen
(plaz´mo-jen) the more vital or essential part of the cytoplasm.

plasmolysis
(plaz-mol´ĭ-sis) contraction of cell protoplasm due to loss of water by osmosis. adj., plasmolyt´ic., adj.

plaster
(plas´tәr) a mixture of materials that hardens; used for immobilizing or making impressions of body parts. an adhesive substance spread on fabric or other suitable backing material, for application to the skin, often containing some medication, such as an analgesic or local vasodilator. ...

plaster bandage
a bandage stiffened with a paste of plaster of Paris.

plaster-of-Paris disease
atrophy of a limb which has been enclosed in a plaster-of-Paris splint.

Plastibell
(plas´tĭ-bel) trademark for a bell-shaped device used as a guide in the removal of the foreskin in circumcision.

plastic
(plas´tik) tending to build up tissues or to restore a lost part. capable of being molded. a high-molecular-weight polymeric material, usually organic, capable of being molded, extruded, drawn, or otherwise shaped and then hardened into a form. material that can be molded.

plastic operation
one in which the shape of a part or the character of its covering is altered by transplantation of tissue or other means.

plastic surgery
surgery concerned with the restoration, reconstruction, correction, or improvement in the shape and appearance of body structures that are defective, damaged, or misshapen by injury, disease, or anomalous growth and development. There are many different types of procedures. Skin grafting and repair of facial defects are s...

plastic suture
a method in which a tongue is cut in one lip of the wound and a groove in the other, the tongue and groove then being stitched together, and the ends of the thread tied over a roll of adhesive plaster.

plasticity
(plas-tis´ĭ-te) the quality of being plastic, or capable of being molded.

plate
(plāt) a flat stratum or layer. dental plate; sometimes, by extension, incorrectly used to designate a complete denture. a flat vessel, usually a Petri dish, containing sterile solid medium for the culture of microorganisms. to prepare a culture medium in a petri dish, or to inoc...

plateau pressure
in mechanical ventilation, the pressure measured at the proximal airway during an end-inspiratory pause; a reflection of alveolar pressure.

plateau pulse
one that is slowly rising and sustained.

plateau wave
a wave seen during intracranial pressure monitoring in advanced stages of increased pressure with hypoxia of brain cells; a rapid increase in pressure is followed by a plateau of high pressure lasting for 5 to 30 minutes before the decline in pressure begins.

platelet
(plāt´lәt) the smallest of the formed elements of the blood, a disk-shaped, non-nucleated cell with a fragile membrane, formed in the red bone marrow by fragmentation of megakaryocytes. Platelets tend to adhere to uneven or damaged surfaces, and there are an average of about 250,000 per mm3 of blood. The bone marro...

platelet agglutination
the clumping together of platelets owing to the action of platelet agglutinins; such agglutinins are important in platelet typing.

platelet agglutinin
an antibody capable of agglutinating platelets; these may be associated with a variety of disorders, with and without frank thrombocytopenia.

platelet count
determination of the total number of platelets per cubic millimeter of blood; the direct platelet count simply counts the cells using a microscope, and the indirect platelet count determines the ratio of platelets to erythrocytes on a peripheral blood smear and computes the number of platelets from the erythrocyte count.

platelet dense body
dense body (def. 2).

platelet inhibitor
any of a group of agents that inhibit the clotting activity of platelets; the most common ones are aspirin and dipyridamole. See also antiplatelet therapy.

platelet-activating factor
(PAF) a substance released by basophils and mast cells in immediate hypersensitivity reactions, and by macrophages and neutrophils in other inflammatory reactions; it leads to bronchoconstriction, platelet aggregation, and release of vasoactive substances from platelets.

platelet-derived growth factor
a substance contained in platelets and capable of inducing proliferation of vascular endothelial cells, vascular smooth muscle cells, fibroblasts, and glial cells; its action contributes to the repair of damaged vascular walls.

plateletpheresis
(plāt″lәt-fә-re´sis) thrombocytapheresis.

platform
(plat´form) a flat horizontal surface higher than the level of the areas around it. force platform a small platform that measures variations in downward force between different points on its surface, for assessing stability of stance and posture as a person stands on it. Called a...

Platinol
(plat´ĭ-nol) trademark for a preparation of cisplatin, an antineoplastic agent.

platinum
(Pt) (plat´ĭ-nәm) a chemical element, atomic number 78, atomic weight 195.09.

platybasia
(plat″ĭ-ba´se-ә) malformation of the base of the skull due to softening of skull bones or a developmental anomaly, with bulging upwards of the floor of the posterior cranial fossa adjacent to the foramen magnum, upward displacement of the upper cervical vertebrae, and bony impingement on the brainstem, ...

platycelous
(plat″ĭ-se´lәs) having one surface flat and the other concave, referring to vertebrae.

platycephalic
(plat″ĭ-sә-fal´ik) having a wide, flat head.

platycoria
(plat″ĭ-kor´e-ә) a dilated condition of the pupil of the eye.

platyhelminth
(plat″ĭ-hel´minth) flatworm.

Platyhelminthes
(plat″ĭ-hәl-min´thēz) the flatworms, a phylum of acoelomate, dorsoventrally flattened, bilaterally symmetrical animals; it includes the classes Cestoidea (tapeworms) and Trematoda (flukes).

platyhieric
(plat″e-hi-er´ik) having a wide sacrum, with a sacral index above 100.

platypellic
(plat″ĭ-pel´ik) having a broad pelvis.

platypellic pelvis
platypelloid pelvis one shortened in the anteroposterior aspect, with a flattened transverse, oval shape.

platypelloid
(plat″ĭ-pel´oid) platypellic.

platypnea
(plә-tip´ne-ә) dyspnea that is relieved when the patient is lying flat; see also orthopnea.

platypodia
(plat″ĭ-po´de-ә) flatfoot.

platyrrhine
(plat´ĭ-rīn) having a broad nose, with a nasal index above 53.

platysma
(plә-tiz´mә) a subcutaneous neck muscle extending from the neck to the clavicle, acting to wrinkle the skin of the neck and to depress the jaw.

platysmal reflex
contraction of the pupil upon nipping of the platysma.

play
(pla) involvement in enjoyable recreational activities; see also play therapy. the extent to which mechanical movement is available. joint play the accessory movement available within a joint, which is not under voluntary control but is needed for proper functioning of the j...

play therapy
a technique used in child psychotherapy in which play is used to reveal unconscious material. Play is the natural way in which children express and work through unconscious conflicts; thus play therapy is analogous to the technique of free association used in psychoanalysis of adults.

playing
(pla´ing) engaging in enjoyable, recreational activity. acting or behaving in a specified way. role playing a technique used in family therapy and group therapy, particularly psychodrama, in which members of the group act out the behavior of others in specific roles in order...

pledget
(plej´әt) a small compress or tuft.

pleiotropism
(pli-ot´rә-piz-әm) pleiotropy.

pleiotropy
(pli-ot´rә-pe) the production by a single gene of multiple phenotypic effects. The term is often used to refer to a single gene defect that is expressed as problems in multiple systems of the body, such as in osteogenesis imperfecta, where the gene defect affects several different systems that contain collagen.

plenum system
a system of ventilation based on the mechanical propulsion of air into the room.

pleocytosis
(ple″o-si-to´sis) more than the normal number of lymphocytes in cerebrospinal fluid.

pleomastia
(ple″o-mas´te-ә) polymastia.

pleomorphic adenoma
a benign, slow-growing tumor of a salivary gland, occurring as a small nodule, usually in a parotid gland but sometimes in another salivary gland; it is usually seen in middle-aged women.

pleomorphic lymphoma
small noncleaved cell lymphoma.

pleomorphic tumor
mixed tumor.

pleomorphism
(ple″o-mor´fiz-әm) the assumption of various distinct forms by a single organism or within a species. adj., pleomor´phic, pleomor´phous., adj.

pleonasm
(ple´o-naz″әm) an excess of parts.

pleonexia
(ple″o-nek´se-ә) a psychiatric disorder characterized by greediness; excessive desire for acquisition of wealth or objects. the condition of being pleonectic.

pleonosteosis
(ple″on-os″te-o´sis) abnormally increased ossification. Léri pleonosteosis a hereditary syndrome of premature and excessive ossification, with short stature, limitation of movement, broadening and deformity of digits, and a face similar to that seen with Down syndrome...

plessesthesia
(ples″es-the´zhә) palpatory percussion.

plethora
(pleth´ә-rә) an excess of blood in a part. by extension, a red florid complexion. adj., pletho´ric., adj.

plethysmograph
(plә-thiz´mo-graf) any device for measuring and recording variations in the volume of an organ, part, or limb. body plethysmograph a device used in pulmonary function tests to measure parameters such as functional residual capacity and the compliance of the lung and thorax; it consi...

plethysmography
(pleth″iz-mog´rә-fe) the determination of changes in volume by means of a plethysmograph. air-cuff plethysmography a technique for measuring changes in the circumference of a limb by recording the changes in pressure in an air-filled cuff surrounding the limb. ...

Pleur-Evac
trademark for a disposable underwater-seal unit designed for drainage of the pleural cavity; it has a graduated collection chamber, permitting immediate and accurate measurement of the amount of drainage from the pleural cavity via the chest tube.

pleura
(ploor´ә) the serous membrane investing the lungs (visceral or pulmonary pleura) and lining the walls of the thoracic cavity (parietal pleura); the two layers enclose a potential space, the pleural cavity. Pleura; for purpose of illustration, the pleural cavity is shown as an actua...

pleuracotomy
(ploor″ә-kot´ә-me) thoracotomy.

pleural
(ploor´әl) pertaining to the pleura.

pleural cavity
the potential space between the two layers of pleura.

pleural effusion
the presence of fluid in the pleural space, between the membrane encasing the lung and that lining the thoracic cavity; types include chylothorax, hemothorax, hydrothorax, and pyothorax (empyema). Conditions that may lead to it include trauma, infections, inflammatory processes, malignancies affecting the pulmonary struct...

pleural fibrosis
fibrosis of the visceral pleura so that part or all of a lung becomes covered with a plaque or a thick layer of nonexpansible fibrous tissue. The more extensive form is called fibrothorax.

pleural plaques
opaque white plaques on the parietal pleura, visible radiographically in cases of asbestosis.

pleural pressure
the pressure between the visceral pleura and the thoracic pleura in the pleural cavity. Called also intrapleural or intrathoracic pressure.

pleuralgia
(pldbobr-ral´jә) pleurodynia. adj., pleural´gic., adj.

pleurapophysis
(ploor″ә-pof´ĭ-sis) a rib, or a vertebral process corresponding to a rib.

pleurectomy
(pldbobr-rek´tә-me) excision of a portion of the pleura.

pleurisy
(ploor´ĭ-se) inflammation of the pleura; the two common types are fibrinous pleurisy and pleurisy with effusion. The cause may be an infection, injury, or tumor; or it may be a complication of a lung disease such as pneumonia, tuberculosis, a lung abscess, or influenza. Symptoms are cough, fever, chills, sharp pain that ...

pleurisy with effusion
a common classification of pleurisy, when it is accompanied by a pleural effusion. Called also exudative or wet pleurisy.

pleuritic pneumonia
pleuropneumonia (def. 1).

pleuritis
(pldbobr-ri´tis) pleurisy.

pleurocele
(ploor´o-sēl) pneumonocele (def. 1).

pleurocentesis
(ploor″o-sen-te´sis) thoracentesis.

pleurocentrum
(ploor″o-sen´trәm) the lateral element of the spinal column.

pleurodesis
(pldbobr-rod´ә-sis) the artificial production of adhesions between the parietal and the visceral pleura for treatment of persistent pneumothorax or severe pleural effusion; formerly done by physically irritating the pleural surface, it is now usually done with a chemical sclerosing agent.

pleurodynia
(ploor″o-din´e-ә) pain in the pleural cavity; called also pleuralgia. costalgia (def. 2). epidemic pleurodynia an epidemic disease usually caused by group B or group A coxsackieviruses, echoviruses, or other enteroviruses. Characteristics include sudden,...

pleuroesophageus muscle
pleuroesophageal muscle: a bundle of smooth muscle fibers usually connecting the esophagus with the left mediastinal pleura.

pleurogenic
(ploor″o-jen´ik) pleurogenous.

pleurogenous
(pldbobr-roj´ә-nәs) originating in the pleura.

pleurography
(pldbobr-rog´rә-fe) radiography of the pleural cavity.

pleurohepatitis
(ploor″o-hep″ә-ti´tis) hepatitis with inflammation of a portion of the pleura near the liver.

pleurolith
(ploor´o-lith) a hard mass or concretion in the pleura.

pleurolysis
(pldbobr-rol´ĭ-sis) surgical separation of pleural adhesions.

pleuroparietopexy
(ploor″o-pә-ri´ә-to-pek″se) the operation of fixing the visceral pleura to the parietal pleura, thus binding the lung to the chest wall.