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

precipitant
(pre-sip´ĭ-tәnt) a substance that causes precipitation.

precipitate
(pre-sip´ĭ-tāt) to cause settling in solid particles of a substance in solution. a deposit of solid particles settled out of a solution. to cause an event or occurrence. (pre-sip´ĭ-tat) occurring with undue rapidity, as precipitate labor.

precipitate labor
delivery accomplished with undue speed.

precipitation
(pre-sip″ĭ-ta´shәn) the act or process of precipitating.

precipitation test
precipitin test.

precipitin
(pre-sip´ĭ-tin) an antibody to antigen that specifically aggregates the antigen in vivo or in vitro to give a visible precipitate.

precipitin reaction
a reaction involving the specific serologic precipitation of an antigen in solution with its specific antiserum in the presence of electrolytes. The reaction is used in the typing of pneumococcus strains, in testing whether blood is human or animal, and for diagnostic purposes.

precipitin test
any test in which the positive reaction consists of the formation and deposit of a precipitate in the fluid being tested. See also precipitin reaction.

precipitinogen
(pre-sip″ĭ-tin´o-jәn) an antigen that stimulates the formation of and reacts with a precipitin.

precision
(pre-sizh´әn) the quality of being sharply or exactly defined. in statistics, the extent to which a measurement procedure gives the same results each time it is repeated under identical conditions.

preclinical
(pre-klin´ĭ-kәl) before a disease becomes clinically recognizable.

preclinical medicine
the subjects studied in medicine before the student observes actual diseases in patients.

preclotting
(pre-klot´ing) the forcing of a patient's blood through the interstices of a knitted vascular prosthesis prior to implantation to render the graft temporarily impervious to blood by disposition of fibrin and platelets in the interstices; after implantation, fibrous ingrowth from the recipient replaces the fibrin-p...

precocity
(pre-kos´ĭ-te) unusually early development of mental or physical traits. adj., preco´cious., adj.

precognition
(pre″kog-nish´әn) the extrasensory perception of a future event.

precoma
(pre-ko´mә) the neuropsychiatric state preceding coma, as in hepatic encephalopathy. adj., precom´atose., adj.

preconscious
(pre-kon´shәs) the part of the mind that is not in immediate awareness but can be consciously recalled with effort, one of the systems of Freud's topographic model of the mind.

precordial leads
leads recording electric potential from various sites over the heart, usually referring to the V leads.

precordial region
the part of the anterior surface of the body covering the heart and the pit of the stomach.

precordium
(pre-kor´de-әm) pl. precor´dia the region over the heart and lower thorax; adj., precor´dial., adj.

precostal
(pre-kos´tәl) in front of the ribs.

precuneal arteries
branches of the pericallosal artery originating in the anterior cerebral artery and supplying the inferior precuneus.

precuneus
(pre-ku´ne-әs) a small convolution on the medial surface of the parietal lobe of the cerebrum.

precursor
(pre´kәr-sәr) something that precedes. In biological processes, a substance from which another, usually more active or mature substance, is formed. In clinical medicine, a sign or symptom that heralds another.

predeciduous tooth
any tooth present at birth, which may be normal in all respects or may represent a hornified, epithelial, rootless structure on the gum over the crest of the ridge before eruption of a deciduous tooth. Called also milk or natal tooth.

prediabetes
(pre-di″ә-be´tēz) a state of latent impairment of carbohydrate metabolism in which the criteria for diabetes mellitus are not all satisfied.

prediastole
(pre″di-as´tә-le) the interval immediately preceding diastole. adj., prediastol´ic., adj.

prediastolic murmur
one occurring just before and with diastole, due to aortic regurgitation or pulmonic regurgitation.

predicrotic
(pre″di-krot´ik) occurring before the dicrotic wave of the sphygmogram.

predigestion
(pre″di-jes´chәn) partial artificial digestion of food before its ingestion into the body.

predisposition
(pre″dis-pә-zish´әn) a latent susceptibility to disease which may be activated under certain conditions.

prediverticular
(pre-di″vәr-tik´u-lәr) denoting a condition of thickening of the muscular wall of the colon and increased intraluminal pressure without evidence of diverticulosis.

prednicarbate
(pred″nĭ-kahr´bāt) a synthetic corticosteroid used topically for the relief of inflammation and pruritus in certain dermatoses.

prednisolone
(pred-nis´ә-lōn″) a synthetic glucocorticoid used in the form of the base or the acetate, sodium phosphate, or tebutate ester in replacement therapy for adrenocortical insufficiency, as an antiinflammatory agent, and as an immunosuppressant.

prednisone
(pred´nĭ-sōn) a synthetic glucocorticoid used as an antiinflammatory and immunosuppressant.

predonated autologous blood
blood donated prior to surgery or other invasive procedure for use in a possible autotransfusion.

predormital paralysis
sleep paralysis occurring prior to falling asleep.

preeclampsia
(pre″ә-klamp´se-ә) a pathologic condition of late pregnancy characterized by edema, proteinuria, and hypertension; it is a precursor to eclampsia if not successfully treated. Although these conditions occur in only 5 to 7 per cent of all pregnancies in the United States, they constitute the third most ...

preexcitation
(pre-ek″si-ta´shәn) abnormal premature activation of part of the ventricular myocardium, signifying conduction of some of the activating impulses by routes outside the normal ones.

preexcitation syndrome
any syndrome with electrocardiographic signs of preexcitation, such as Wolff-Parkinson-White syndrome; sometimes used synonymously with it.

prefollicle cells
cells encapsulating the primordial germ cells in the fetal ovary. Called also primordial granulosa cells.

preformed catheter
a preshaped catheter designed to require less operator manipulation but usually restricted to a single function.

prefrontal
(pre-fron´tәl) situated in the anterior part of the frontal region or lobe. the central part of the ethmoid bone.

prefrontal area
the cortex of the frontal lobe immediately in front of the premotor area, concerned chiefly with associative functions.

prefrontal artery
origin, superior terminal branch of middle cerebral artery; branches, none; distribution, prefrontal area of cerebrum.

prefrontal veins
a group of superior cerebral veins, that is, superficial cerebral veins that drain the prefrontal area of the cerebral cortex.

preganglionic
(pre″gang-gle-on´ik) proximal to a ganglion.

preganglionic fibers
nerve fibers that pass to the autonomic ganglia and have their cell bodies in the brain or spinal cord.

preganglionic neurons
neurons whose cell bodies lie in the central nervous system and whose efferent fibers terminate in the autonomic ganglia.

pregenital
(pre-jen´ĭ-tәl) pertaining to the early stages of psychosexual development (oral and anal), before the genitals have become the dominant influence on sexual behavior.

preglomerular arteriole
afferent glomerular arteriole.

pregnancy
(preg´nәn-se) the condition of having a developing embryo or fetus in the body, after union of an oocyte and spermatozoon. It is marked by cessation of the menses; nausea on arising in the morning (morning sickness); enlargement of the breasts and pigmentation of the nipples; progressive enlargement of the abdomen...

pregnancy cell
an altered chromophobe cell found in the adenohypophysis in pregnant women.

pregnancy gingivitis
any of various gum changes seen in pregnancy, ranging from gingivitis to the so-called pregnancy tumor.

pregnancy test
a procedure for early determination of pregnancy. By the first missed menstrual period or shortly thereafter, human chorionic gonadotropin (hCG), a hormone secreted by the placenta, is present in the blood and urine of a pregnant woman. This was formerly determined by bioassay in which a urine or serum specimen was injected int...

pregnancy tumor
a tumorous type of gingivitis, histologically and clinically identical to angiogranuloma or pyogenic granuloma. It is most common in pregnant women, especially in the third trimester, resulting from minor trauma or irritation that is probably intensified by the endocrine alteration of pregnancy; it may or may not regress after ...

pregnancy-induced hypertension
(PIH) preeclampsia/eclampsia.

pregnane
(preg´nān) a crystalline saturated steroid hydrocarbon; β-pregnane is the form from which several hormones, including progesterone, are derived; α-pregnane is the form excreted in the urine.

pregnanediol
(preg″nān-di´ol) a crystalline, biologically inactive end product of progesterone metabolism, found especially in the urine of pregnant women and during the premenstrual and luteal phases of the menstrual cycle.

pregnanetriol
(preg″nān-tri´ol) a metabolite of 17-hydroxyprogesterone; its excretion in the urine is greatly increased in disorders of the adrenal cortex such as adrenal hyperplasia.

pregnant
(preg´nәnt) with child; having a developing embryo or fetus within the uterus; called also gravid.

prehallux
(pre-hal´әks) an abnormal extra bone of the foot that grows from the medial border of the scaphoid.

prehensile
(pre-hen´sil) adapted for grasping or seizing.

prehension
(pre-hen´shәn) the act of grasping.

Prehn sign
elevation and support of the scrotum will relieve the pain in epididymo-orchitis, but not in torsion of the testicle.

prehormone
(pre-hor´mōn) prohormone.

preictal
(pre-ik´tәl) occurring before a stroke, seizure, or attack.

preinfarction angina
angina that lasts longer than 15 minutes; it is a symptom of worsening cardiac ischemia.

preinvasive
(pre″in-va´siv) not yet invading tissues outside the site of origin.

preinvasive carcinoma
c. in situ.

Preiser disease
(pri´zer) osteoporosis and atrophy of the carpal scaphoid due to trauma or a fracture which has not been kept immobilized.

prekallikrein
(pre″kal-ĭ-kre´in) a plasma protein that is the proenzyme of plasma kallikrein; it is cleaved to its active enzyme form by activated factor XII.

preleukemia
(pre-loo-ke´me-ә) a stage of bone marrow dysfunction preceding the development of acute myelogenous leukemia. adj., preleuke´mic., adj.

prelimbic
(pre-lim´bik) in front of a limbus.

prelingual hearing loss
that acquired before the person has learned to speak.

preload
(pre´lōd) the volume of blood in a ventricle of the heart at the end of diastole.

premalignant
(pre″mә-lig´nәnt) precancerous.

premalignant fibroepithelial tumor
premalignant fibroepithelioma.

premalignant fibroepithelioma
a rare, usually indolent variant of basal cell carcinoma, presenting as a firm sessile to pedunculated papule, usually on the lower trunk or lumbosacral area in middle-aged or older adults. Histologically it is characterized by prominent stromal fibrosis with long anastomosing cords of basal cells.

Premarin
(prem´ә-rin) trademark for preparations of conjugated estrogens.

premature
(pre-mә-chldbomacr´) born or interrupted before the state of maturity; occurring before the proper time.

premature beat
a type of heartbeat resulting from discharge by an atrial, junctional, or ventricular focus before the next expected sinus beat and at an interval from the last sinus beat that is shorter than its own intrinsic rhythm.

premature infant
one usually born after the twentieth completed week and before full term, arbitrarily defined as one weighing 500 to 2499 g (2.2 to 5.5 lb) at birth, having poor to good chance of survival, depending on the weight. In countries where adults are smaller than in the United States, the upper limit may be lower. ...

premature labor
preterm labor labor commencing before the expected end of gestation, usually meaning between 20 and 37 completed weeks after onset of the last menstrual period. It can be arrested (see tocolysis) and does not necessarily lead to preterm delivery.

premature teeth
deciduous teeth that erupt prior to the end of the third month of life, or permanent teeth that erupt prior to the end of the fourth year of life. See also predeciduous teeth.

prematurity
(pre″mә-chldbomacr´ĭ-te) underdevelopment. the condition of a premature infant.

premaxilla
(pre″mak-sil´ә) a separate element derived from the median nasal processes in the embryo, which later fuses with the maxilla.

premaxillary
(pre-mak´sĭ-lar´e) situated in front of the maxilla proper. incisive bone.

premaxillary bone
premaxilla.

premedication
(pre″med-ĭ-ka´shәn) preliminary administration of a drug preceding a diagnostic, therapeutic, or surgical procedure, as an antibiotic or antianxiety agent. a drug administered for such a purpose.

premenarchal
(pre″mә-nahr´kәl) premenarcheal.

premenarcheal
(pre″mә-nahr´ke-әl) occurring before establishment of menstruation.

premenopausal
(pre″men-o-paw´zәl) preceding menopause.

premenstrual
(pre-men´stroo-әl) preceding menstruation.

premenstrual acne
acne that appears shortly before menses (or occasionally after).

premenstrual dysphoric disorder
premenstrual syndrome viewed as a psychiatric disorder.

premenstrual syndrome
(PMS) a syndrome of unknown cause, typically occurring in the period between ovulation and the onset of menstruation, marked by some or all of the following symptoms: feelings of depression, hopelessness, anxiety, or anger, emotional lability, bloating, edema, headache, increased fatigue or lethargy, changes...

premenstrual tension
premenstrual syndrome.

premenstruum
(pre-men´stroo-әm) the period immediately before menstruation.

premolar
(pre-mo´lәr) in front of a molar tooth. a premolar tooth.