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

phase
(fāz) one of the aspects or stages through which a varying entity may pass. In physical chemistry, any physically or chemically distinct, homogeneous, and mechanically separable part of a system.

phase 0
in cardiac physiology, the phase representing the upstroke of the action potential, in which rapid depolarization occurs after the cell reaches or is driven to threshold potential. It is the result of the opening of fast sodium channels and calcium channels.

phase 1
in cardiac physiology, the initial rapid repolarization phase of the action potential, caused by the closure of the fast sodium channels and an exodus of potassium from the cell.

phase 2
in cardiac physiology, the phase representing the plateau of the action potential, which contributes to the refractory period of the heart; there is a slow entry of calcium into the cell. It is the result of a balance between inward and outward currents and is particularly long in Purkinje and ventricular cells.

phase 3
in cardiac physiology, the terminal rapid repolarization phase of the action potential; it begins with the closing of the slow channels, resulting in an exodus of potassium from the cell and the activation of the sodium-potassium pump. The result is reestablishment of the normal resting potential.

phase 4
in cardiac physiology, the phase representing electrical diastole, i.e. the time between action potentials. It is the resting phase of the electrical cardiac cycle and is steadily maintained in nonpacemaker cells. In pacemaker cells, the membrane potential is normally reduced slowly until threshold potential is reached; if there is a...

phase microscope
phase-contrast microscope a microscope that alters the phase relationships of the light passing through and that passing around the object, the contrast permitting visualization of the object without the necessity for staining or other special preparation.

phaseolamin
(fә-se″o-lam´in) an alpha-amylase inhibitor purified from the kidney bean (Phaseolus vulgaris); it is the basis of starch-blocker tablets. an α-amylase inhibitor purified from the kidney bean (Phaseolus vulgaris); it has been used in preparations alleged to enhance weight control by preventing a...

phasic reflex
coordinated reflex.

phasmid
(faz´mid) either of the two caudal chemoreceptors occurring in certain nematodes (Phasmidia). any nematode containing phasmids.

PHC syndrome
an autosomal dominant syndrome consisting of premolar aplasia, hyperhidrosis, and premature canities. Called also Böök syndrome.

Phe
phenylalanine.

Phelps operation
an open and direct incision through the sole and inner side of the foot, done for talipes.

Phemister graft
a bone graft of cortical bone with cancellous bone chips to enhance callus formation.

Phemister operation
use of an onlay graft of cancellous bone without internal fixation, for treatment of a stable but ununited fracture.

phenacemide
(fә-nas´ә-mīd) an anticonvulsant used in psychomotor and grand mal epilepsy.

phenanthrene
(fә-nan´thrēn) a tricyclic aromatic hydrocarbon occurring in coal tar and isomeric with anthracene; it is toxic and carcinogenic.

phenarsazine chloride
(fen-ahr´sә-zēn) a toxic compound used as a gas in war and, as a compound with tear gas, in riot control; also used in some wood preserving solutions. It irritates the skin and respiratory tract and also causes nausea, vomiting, depression, and weakness. Called also adamsite and diphenylaminechlorarsine...

phenazone
(fen´ә-zōn) antipyrine.

phenazopyridine
(fen″ә-zo-pēr´ĭ-dēn) a urinary tract analgesic, used as the hydrochloride salt; administered orally.

phencyclidine
(fen-si´klĭ-dēn) a central nervous system depressant, introduced as an anesthetic in the early 1950s but later abandoned because of unpredictable side effects such as agitation, disorientation, and hallucination; now seen mainly as a drug of abuse. (See drug abuse.) It has a variety of street names, such as &#...

phendimetrazine
(fen″di-met´rә-zēn) a sympathomimetic amine with pharmacologic actions similar to those of the amphetamines, used as the tartrate salt as an appetite suppressant.

phenelzine
(fen´әl-zēn) a monoamine oxidase inhibitor, administered orally as the sulfate salt as an antidepressant and in the prevention of migraine.

Phenergan
(fen´әr-gәn) trademark for preparations of promethazine, an antihistamine, antiemetic, and sedative.

phenethyl alcohol
phenylethyl alcohol a colorless liquid used as an antimicrobial agent in pharmaceuticals.

phenindamine
(fә-nin´dә-mēn) an antihistamine with sedative and anticholinergic effects; used as the tartrate salt in the treatment of nasal, eye, and skin manifestations of allergic reactions, including allergic rhinitis, conjunctivitis, and itching, and also as an ingredient in some cough and cold preparations, ad...

pheniramine
(fĕ-nir´ә-mēn) an antihistamine with sedative properties, used as the maleate salt in the treatment of allergic disorders, including rhinitis, conjunctivitis, and pruritic skin disorders; administered orally, intranasally, or topically to the conjunctiva. It is also used as an ingredient in cough and col...

Phenistix
(fen´ĭ-stiks) trademark for a reagent strip impregnated with ferric chloride and glacial acetic acid; used in screening tests for phenylketonuria and in detection of salicylates and chlorpromazine in the urine.

phenmetrazine
(fen-met´rә-zēn) a central nervous system stimulant, used as an appetite suppressant in the form of the hydrochloride salt; abuse may lead to habituation.

phenobarbital
(fe″no-bahr´bĭ-tәl) a long-acting barbiturate used as the base or the sodium salt as an anticonvulsant, sedative, and hypnotic.

phenocopy
(fe´no-kop″e) an environmentally induced phenotype mimicking one usually produced by a specific genotype. an individual exhibiting such a phenotype; the simulated trait in a phenocopy.

phenol
(fe´nol) an extremely poisonous compound, used in dilute solution as an antimicrobial, anesthetic, and antipruritic. Ingestion or absorption through the skin causes symptoms including colic, local irritation, corrosion, seizures, cardiac arrhythmias, shock, and respiratory arrest. Phenol should be properly labeled...

phenol block
phenol neurolysis. phenol motor point block.

phenol coefficient
a measure of the bactericidal activity of a chemical compound in relation to phenol. The activity of the compound is expressed as the ratio of dilution in which it kills in 10 minutes but not in 5 minutes under the specified conditions. It can be determined in the absence of organic matter, or in the presence of a standar...

phenol motor point block
the most common method of motor point block; a solution of 5 per cent phenol in water is injected at the motor point. Called also phenol block.

phenol neurolysis
chemical neurolysis in which a solution of 5 to 7.5 per cent phenol in glycerol is injected under the dura mater of the spinal cord, into a dorsal root ganglion.

phenol poisoning
poisoning due to ingestion or absorption through the skin of phenol; symptoms include colic, local irritation, corrosion, seizures, cardiac arrhythmias, shock, and respiratory arrest. Called also carbolism.

phenol test
see specific tests, including Jacquemin test.

phenolphthalein
(fe″nol-thal´ēn) a cathartic and pH indicator.

phenolphthalein test
(for blood) boil a thin fecal suspension, cool, and add it to half as much reagent (made by dissolving 1 to 2 g of phenolphthalein and 25 g of potassium hydroxide in water). Add 10 g of metallic zinc and heat until decolorized. A pink color indicates the presence of blood. (in urine) make the urine alkaline;...

phenomenology
(fә-nom″ә-nol´ә-je) the study of phenomena in their own right rather than inferring causes; in psychiatry, the theory that behavior is determined by the way the person perceives reality rather than by objective external reality.

phenomenon
(fә-nom´ә-non) pl. phenom´ena any sign or objective symptom; any observable occurrence or fact.

phenothiazine
(fe″no-thi´ә-zēn) any of a group of drugs that all have similar tricyclic structures and act as potent dopaminergic and alpha-adrenergic blocking agents; they also have hypotensive, antispasmodic, antihistaminic, analgesic, sedative, and antiemetic activity.

phenotype
(fe´no-tīp) the observable morphological, biochemical, and physiological characteristics of an individual, either in whole or with respect to a single or a few traits, as determined by a combination of the genotype and the environment. adj., phenotyp´ic., adj.

phenoxybenzamine
(fә-nok″se-ben´zә-mēn) an adrenergic blocking agent; the hydrochloride salt is used to control hypertension in pheochromocytoma and to treat urinary symptoms in benign prostatic hyperplasia.

phenozygous
(fe″no-zi´gәs) having the calvaria narrower than the face, so that the zygomatic arches are visible when the head is viewed from above.

phensuximide
(fen-suk´sĭ-mīd) an anticonvulsant used in the treatment of absence epilepsy; administered orally.

phentermine
(fen´tәr-mēn) a sympathomimetic amine related to amphetamine, used as an appetite suppressant either as the hydrochloride salt or as the base in a complex with a resin, which has a sustained action.

phentolamine
(fen-tol´ә-mēn) a potent alpha-adrenergic blocking agent that blocks the hypertensive action of epinephrine and norepinephrine and most responses of smooth muscles that involve alpha-adrenergic receptors. Its mesylate salt is used intravenously or intramuscularly to prevent and treat hypertension occurring before a...

Phenurone
(fen´u-rōn) trademark for a preparation of phenacemide, an anticonvulsant.

phenyl
(fen´әl) (fe´nәl) the monovalent radical C6H5sbond, derived from benzene by removal of hydrogen. adj., phenyl´ic., adj.

phenylacetic acid
(fen″әl-ә-se´tik) a catabolite of phenylalanine; it is excessively formed and excreted, sometimes conjugated with glutamine, in phenylketonuria.

phenylalanine
(fen″әl-al´ә-nēn) a naturally occurring essential amino acid that is necessary for optimal growth in infants and for nitrogen equilibrium in adults. phenylalanine hydroxylase , phenylalanine 4-monooxygenase an enzyme that activates molecular oxygen ...

phenylalaninemia
(fen″әl-al″ә-nĭ-ne´me-ә) hyperphenylalaninemia.

phenylbutazone
(fen″әl-bu´tә-zōn) a nonsteroidal antiinflammatory drug administered orally in the short-term treatment of severe rheumatoid disorders unresponsive to less toxic agents.

phenylephrine
(fen″әl-ef´rin) an adrenergic with potent vasoconstrictor properties; used as the hydrochloride salt for various purposes: topically to decongest nasal and laryngeal mucous membranes or to produce mydriasis without cycloplegia; intravenously to maintain blood pressure during spinal and inhalation anesthesia,...

phenylketonuria
(PKU) (PKU1) (fen″әl-ke″to-nu´re-ә) a congenital disease due to a defect in metabolism of the amino acid phenylalanine. The condition is hereditary and transmitted as a recessive trait. Symptoms result from lack of an enzyme that normally should convert phenyl...

phenylmercuric
(fen″әl-mәr-ku´rik) denoting a compound containing the radical C6H5Hg—, forming various antiseptic, antibacterial, and fungicidal salts; compounds of the acetate and nitrate salts are used as bacteriostatic preservatives in pharmaceuticals, and the former is also used as an herbicide.

phenylpropanolamine
(fen″әl-pro″pә-nol´ә-mēn) an adrenergic used in the form of the hydrochloride salt as a nasal and sinus decongestant, as an appetite suppressant, and in the treatment of mild to moderate stress incontinence.

phenylpyruvic acid
(fen″әl-pi-roo´vik) an intermediate product of the metabolism of phenylalanine in the body.

phenyltoloxamine
(fen″il-to-lok´sah-mēn) a sedating antihistamine, used as the citrate salt in cough and cold preparations.

phenytoin
(fen´ĭ-toin″) an anticonvulsant used in the treatment of epilepsy other than the absence type, the treatment of status epilepticus, and the prevention and treatment of seizures associated with neurosurgery; administered orally. Called also diphenylhydantoin.

pheochrome
(fe´o-krōm″) chromaffin.

pheochrome cells
chromaffin cells.

pheochromoblast
(fe″o-kro´mo-blast) any of the embryonic structures that develop into chromaffin(pheochrome) cells.

pheochromocyte
(fe″o-kro´mo-sīt) a chromaffin cell.

pheochromocytoma
(fe″o-kro″mo-si-to´mә) a small tumor of the chromaffin cells, usually in the adrenal medulla but occasionally in chromaffin tissue of the sympathetic paraganglia. It is relatively rare and tends to occur in families. It can be cured if diagnosed early, but can be fatal once it causes irreparable damage...

pheresis
(fә-re´sis) apheresis.

pheromone
(fer´ә-mōn) a substance secreted to the outside of the body and perceived (as by smell) by other individuals of the same species, releasing specific behavior in the percipient.

PhG
Graduate in Pharmacy.

phi phenomenon
the perception of the sequential flashing of a stationary row of lights as a moving light.

Phialophora
(fi″ә-lof´ә-rә) a genus of imperfect fungi. P. verruco´si is a cause of chromoblastomycosis and P. jeansel´mi is a cause of maduromycosis.

Philadelphia chromosome
an abnormality of chromosome 22, characterized by shortening of its long arms (the missing portion usually translocated to chromosome 9) and present in marrow cells of most patients with chronic granulocytic leukemia.

Philippine hemorrhagic fever
hemorrhagic dengue.

Philippson reflex
excitation of the knee extensor on one side induced by inhibition in the extensor of the other.

philtrum
(fil´trәm) the vertical groove in the median portion of the upper lip.

phimosis
(fi-mo´sis) constriction of the orifice of the prepuce so that it cannot be drawn back over the glans. adj., phimot´ic., adj.

pHisoHex
(fi´so-heks″) trademark for an emulsion containing hexachlorophene; used as a skin cleanser.

phlebangioma
(fleb″an-je-o´mә) a venous aneurysm.

phlebarteriectasia
(fleb″ahr-tēr″e-ek-ta´zhә) general dilatation of veins and arteries.

phlebectasia
(fleb″ek-ta´zhә) varicosity (def. 1).

phlebectomy
(flә-bek´tә-me) excision of a vein, or a segment of a vein.

phlebemphraxis
(fleb″әm-frak´sis) stoppage of a vein by a plug or clot.

phlebitis
(flә-bi´tis) inflammation of a vein, especially one in a lower limb. It is usually not serious in a superficial vein, since these veins are numerous enough to permit blood flow to be rechanneled so that it bypasses the inflamed vein. In a deep vein or one inside the skull, it may be more dangerous; see also ...

phleboclysis
(flә-bok´lĭ-sis) injection of fluid into a vein; see also intravenous infusion. Called also venoclysis.

phlebogram
(fleb´o-gram) a radiograph of a vein filled with contrast medium. a phlebographic or sphygmographic tracing of the venous pulse.

phlebograph
(fleb´o-graf) an instrument for recording the venous pulse.

phlebography
(flә-bog´rә-fe) angiography of a vein or veins. the graphic recording of the venous pulse; called also venography.

phlebolith
(fleb´o-lith) a calculus in a vein.

phlebolithiasis
(fleb″o-lĭ-thi´ә-sis) the development of phleboliths.

phlebomanometer
(fleb″o-mә-nom´ә-tәr) an instrument for the direct measurement of venous blood pressure.

phlebophlebostomy
(fleb″o-flә-bos´tә-me) operative anastomosis of one vein to another, as of the portal vein and inferior vena cava.

phleboplasty
(fleb´o-plas″te) plastic repair of a vein.

phleborrhaphy
(flә-bor´ә-fe) suturing of a vein.

phleborrhexis
(fleb″o-rek´sis) rupture of a vein.

phlebosclerosis
(fleb″o-sklә-ro´sis) fibrous thickening of the walls of veins; called also venosclerosis.

phlebostasis
(flә-bos´tә-sis) venous stasis. temporary sequestration of a portion of blood from the general circulation by compressing the veins of a limb.

phlebostatic axis
a point located by drawing an imaginary line from the fourth intercostal space at the sternum and finding its intersection with an imaginary line drawn down the center of the chest below the armpits.

phlebothrombosis
(fleb″o-throm-bo´sis) the development of venous thrombi in the absence of associated inflammation of the vessel wall; it is to be distinguished from thrombophlebitis, in which there are inflammatory changes in the vessel wall. Called also venous thrombosis.

phlebotomist
(flә-bot´ә-mist) a health professional trained in the opening of veins for the withdrawal of blood.