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Medical Dictionary


viscance (vis′kans)
A measure of the energy dissipation due to a flow in a viscous system. In medicine and physiology, usually a measure of the energy dissipation in the flow of liquids, sols, or gels within cells and tissues, or of fluids ( e.g., blood, respiratory gases) in tubes. The v. is the pressure gradient from one end to the other of the flow path when unit flow occurs. The relationship between viscosity and v. is of the same nature as that between specific resistance, or resistivity, of a conductor material and the resistance of a particular conductor made from that material.

viscera (vis′er-a)
Plural of viscus. SYN: vitals.

viscerad (vis′er-ad)
In a direction toward the viscera. [viscera + L. ad, to]

visceral (vis′er-al)
Relating to the viscera. SYN: splanchnic.

visceralgia (vis-er-al′je-a)
Pain in any viscera. [viscera + G. algos, pain]

viscerimotor (vis′er-i-mo′ter)
SYN: visceromotor.

The viscera. SEE ALSO: splanchno-. [L. viscus, pl. viscera, the internal organs]

viscerocranium (vis′er-o-kra′ne-um) [TA]
That part of the skull derived from the embryonic pharyngeal arches; it comprises the facial bones of the facial skeleton (under bone) and is distinct from that part of the skull which forms the neurocranium or braincase. SYN: facial skeleton&star, cranium viscerale, visceral cranium, jaw skeleton, splanchnocranium. [viscero- + cranium] cartilaginous v. those elements of the fetal skull derived from the pharyngeal arch cartilages. membranous v. components of v. that do not arise from a cartilagenous precursor; most of the mandible is a membrane bone, developing around and not from the first pharyngeal arch cartilage.

viscerogenic (vis′er-o-jen′ik)
Of visceral origin; denoting a number of sensory and other reflexes. [viscero- + G. -gen, producing]

viscerograph (vis′er-o-graf)
An instrument for recording the mechanical activity of the viscera. [viscero- + G. grapho, to write]

visceroinhibitory (vis′er-o-in-hib′i-tor-e)
Restricting or arresting the functional activity of the viscera.

visceromegaly (vis′er-o-meg′a-le)
Abnormal enlargement of the viscera, such as may be seen in acromegaly and other disorders. SYN: organomegaly, splanchnomegaly. [viscero- + G. megas, large]

visceromotor (vis′er-o-mo′ter)
1. Relating to or controlling movement in the viscera; denoting the autonomic nerves innervating the viscera, especially the intestines. 2. Denoting a movement having a relation to the viscera; referring to reflex muscular contractions of the abdominal wall in cases of visceral disease. SYN: viscerimotor.

visceroparietal (vis′er-o-pa-ri′e-tal)
Relating to the viscera and the wall of the abdomen. [viscero- + L. paries, wall]

visceroperitoneal (vis′er-o-per-i-to-ne′al)
Relating to the peritoneum and the abdominal viscera.

visceropleural (vis′er-o-ploo′ral)
Relating to the pleural and the thoracic viscera. SYN: pleurovisceral.

visceroptosis, visceroptosia (vis′er-op-to′sis, -to′se-a)
Descent of the viscera from their normal positions. SYN: splanchnoptosis, splanchnoptosia. [viscero- + G. ptosis, a falling]

viscerosensory (vis′er-o-sen′sor-e)
Relating to the sensory innervation of internal organs.

visceroskeletal (vis-er-o-skel′e-tal)
Relating to the visceroskeleton. SYN: splanchnoskeletal.

visceroskeleton (vis-er-o-skel′e-ton)
1. Any bony formation in an organ, as in the heart, tongue, or penis of certain animals; the term also includes, according to some anatomists, the cartilaginous rings of the trachea and bronchi. 2. The bony framework protecting the viscera, such as the ribs and sternum, the pelvic bones, and the anterior portion of the skull. SYN: splanchnoskeleton, visceral skeleton.

viscerosomatic (vis′er-o-so-mat′ik)
Relating to the viscera and the body. SYN: splanchnosomatic. [viscero- + G. soma, body]

viscerotome (vis′er-o-tom)
An instrument by means of which a section of an organ, e.g., the liver, can be removed from a cadaver for examination without performing a general autopsy. [viscero- + G. tomos, cutting]

viscerotomy (vis-er-ot′o-me)
Dissection of the viscera by incision, especially postmortem. [viscero- + G. tome, incision]

viscerotonia (vis′er-o-to′ne-a)
Personality traits of love of food, sociability, general relaxation, friendliness, and affection. [viscero- + G. tonos, tone]

viscerotrophic (vis′er-o-trof′ik)
Relating to any trophic change determined by visceral conditions. [viscero- + G. trophe, nourishment]

viscerotropic (vis′er-o-trop′ik)
Affecting the viscera. [L. viscero, internal organs, + G. trope, a turning]

viscid (vis′id)
Sticky; glutinous. [L. viscidus, stick, fr. viscum, birdlime]

viscidity (vi-sid′i-te)
Stickiness; adhesiveness.

viscidosis (vis-i-do′sis)
SYN: cystic fibrosis.

viscoelasticity (vis′ko-e-las-tis′i-te)
The property of a viscous material that also shows elasticity.

viscometer (vis-kom′e-ter)
SYN: viscosimeter.

viscosimeter (vis-ko-sim′e-ter)
An apparatus for determining the viscosity of a fluid; in medicine, usually of the blood. SYN: viscometer.

viscosimetry (vis-ko-sim′e-tre)
Determination of the viscosity of a fluid, such as the blood. [viscosity + G. metron, measure]

viscosity (vis-kos′i-te)
In general, the resistance to flow or alteration of shape by any substance as a result of molecular cohesion; most frequently applied to liquids as the resistance of a fluid to flow because of a shearing force. [L. viscositas, fr. viscosus, viscous] absolute v. force per unit area applied tangentially to a fluid, causing unit rate of displacement of parallel planes separated by a unit distance; units in CGS system: poise. anomalous v. the viscous behavior of nonhomogenous fluids or suspensions, e.g., blood, in which the apparent v. increases as flow or shear rate decreases toward zero. apparent v. the v. calculated from Poiseuille law at any particular flow and tube diameter; it is used for suspensions, such as blood, that exhibit anomalous v. and the Fahraeus-Lindqvist effect. dynamic v. (μ) the internal or molecular frictional resistance of a fluid by Newton law of v. as the ratio of the applied force per unit area to the relative velocity of adjacent fluid layers (produced by the force). kinematic v. (ν, Υ) a measure used in studies of fluid flow; it is the dynamic v., μ, in poises, divided by the density of the material; unit; stoke. newtonian v. the v. characteristics of a newtonian fluid. relative v. the ratio of the v. of a solution or dispersion to the v. of the solvent or continuous phase.

viscotoxins (vis′ko-toks′ins)
A class of phytotoxins that have a hypotensive activity and slow the heart beat.

viscous (vis′kus)
Sticky; marked by high viscosity. [see viscid, viscosity]

viscum (vis′kum)
1. The berries of V. album (family Loranthaceae), a parasitic plant growing on apple, pear, and other trees; has been used as an oxytocic. SYN: mistletoe. 2. Herbage of Phoradendron flavescens, American mistletoe; has been used as an oxytocic and emmenagoque.

viscus, pl .viscera (vis′kus, vis′er-a)
An organ of the digestive, respiratory, urogenital, and endocrine systems as well as the spleen, the heart, and great vessels; hollow and multilayered walled organs studied in splanchnology. [L. the soft parts, internal organs]

vision (vizh′un)
The act of seeing. SEE ALSO: sight. [L. visio, fr. video, pp. visus, to see] achromatic v. SYN: achromatopsia. binocular v. v. with a single image, by both eyes simultaneously. blue v. SYN: cyanopsia. central v. v. stimulated by an object imaged on the fovea centralis. SYN: direct v.. chromatic v. SYN: chromatopsia. colored v. (VC) SYN: chromatopsia. cone v. SYN: photopic v.. direct v. SYN: central v.. double v. SYN: diplopia. facial v. sensing the proximity of objects by the nerves of the face, presumed in the case of the blind and also in sighted persons who are blindfolded or in darkness. green v. SYN: chloropsia. halo v. a condition in which colored or luminous rings are seen around lights. haploscopic v. stereoscopic v. produced by the haploscope, or mirror-type stereoscope. indirect v. SYN: peripheral v.. multiple v. SYN: polyopia. night v. SYN: scotopic v.. oscillating v. SYN: oscillopsia. peripheral v. v. resulting from retinal stimulation beyond the macula. SYN: indirect v.. photopic v. v. when the eye is light-adapted. See light adaptation, light-adapted eye. SYN: cone v., photopia. red v. SYN: erythropsia. rod v. SYN: scotopic v.. scotopic v. v. when the eye is dark-adapted. SEE ALSO: dark adaptation, dark-adapted eye. SYN: night v., rod v., scotopia, twilight v.. stereoscopic v. the single perception of a slightly different image from each eye. SYN: stereopsis. subjective v. visual impressions that arise centrally and do not originate with ocular stimuli. tinted v. SYN: chromatopsia. triple v. SYN: triplopia. tubular v. a constriction of the visual field, as though one were looking through a hollow cylinder or tube. SYN: tunnel v.. tunnel v. SYN: tubular v.. twilight v. SYN: scotopic v.. yellow v. SYN: xanthopsia.

visual (vizh′oo-al)
1. Relating to vision. 2. Denoting a person who learns and remembers more readily through sight than through hearing. SEE ALSO: internal representation. [Late L. visualis, fr. visus, vision] functional v. loss an apparent loss of v. acuity or v. field with no substantiating physical signs; often due to a natural concern about v. loss combined with suggestibility and a fear of the worst; best treated with reassurance.

visualize (vizh′oo-a-liz)
To picture in the mind or to perceive; commonly misused by ascribing to the technique the act of making visible.

visuoauditory (vizh′u-o-aw′di-tor-e)
Relating to both vision and hearing; denoting nerves connecting the centers for these senses.

visuognosis (vizh′u-og-no′sis)
Recognition and understanding of visual impressions. [L. visus, vision, + G. gnosis, knowledge]

visuomotor (viz′u-o-mo′ter)
Denoting the ability to synchronize visual information with physical movement, e.g., driving a car or playing a video game of skill.

visuopsychic (vizh′u-o-si′kik)
Pertaining to the portion of the cerebral cortex concerned with the integration of visual impressions. [L. visus, vision, + G. psyche, mind]

visuosensory (vizh′u-o-sen′sor-e)
Pertaining to the perception of visual stimuli.

visuospatial (viz′u-o-spa′shal)
Denoting the ability to comprehend and conceptualize visual representations and spatial relationships in learning and performing a task.

visuscope (viz′u-skop)
A modified ophthalmoscope that projects a black star on the patient's fundus.

vital (vit-al)
Relating to life. [L. vitalis, fr. vita, life]

vitalism (vit′al-izm)
The theory that animal functions are dependent upon a special form of energy or force, the vital force, distinct from the physical forces. SYN: vis vitae, vis vitalis. [L. vitalis, pertaining to life]

vitalistic (vit′a-lis′tik)
Pertaining to vitalism.

vitality (vit-al′i-te)
Vital force or energy.

vitalize (vit′al-iz)
To endow with vital force.

vitalometer (vi-ta-lom′e-ter)
An electrical device for determining the vitality of the tooth pulp.

vital red [C.I. 23570]
Trisodium salt of a sulfonated diazo dye (a ditolyl group diazotized to sulfonated aminonaphthalene residues), used as a vital stain. SYN: brilliant v..

vitals (vit′alz)
SYN: viscera.

vitamer (vi′ta-mer)
One of two or more similar compounds capable of fulfilling a specific vitamin function in the body; e.g., niacin, niacinamide.

vitamin (vit′a-min)
One of a group of organic substances, present in minute amounts in natural foodstuffs, that are essential to normal metabolism; insufficient amounts in the diet may cause deficiency diseases. [L. vita, life, + amine] v. A 1. any β-ionone derivative, except provitamin A carotenoids, possessing qualitatively the biological activity of retinol; deficiency interferes with the production and resynthesis of rhodopsin, thereby causing night blindness, and produces a keratinizing metaplasia of epithelial cells that may result in xerophthalmia, keratosis, susceptibility to infections, and retarded growth; 2. the original v. A, now known as retinol. SYN: axerophthol. v. A1 SYN: retinol. v. A2 SYN: dehydroretinol. v. A1 acid SYN: retinoic acid. v. A1 alcohol SYN: retinol. v. A aldehyde SYN: retinaldehyde. v. A2 aldehyde SYN: dehydroretinaldehyde. antiberiberi v. SYN: thiamin. antihemorrhagic v. SYN: v. K. antineuritic v. SYN: thiamin. antirachitic vitamins ergocalciferol (v. D2) and cholecalciferol (v. D3). antiscorbutic v. SYN: ascorbic acid. antisterility v. SYN: v. E (2) . v. B a group of water-soluble substances originally considered as one v.. v. B1 SYN: thiamin. v. B2 1. SYN: riboflavin. 2. obsolete term for a complex of folic acid, nicotinic acid, nicotinamide, pantothenic acid, and riboflavin. v. B3 1. obsolete term for nicotinamide and/or nicotinic acid; 2. obsolete term for pantothenic acid. v. B4 1. once believed to be a factor necessary for nutrition of the chick, now identified simply as certain essential amino acids and/or adenine; 2. obsolete term for adenine. v. B5 term once used to describe biologic activities now ascribed to pantothenic acid or nicotinic acid. v. B6 pyridoxine and related compounds (pyridoxal; pyridoxamine). v. B12 generic descriptor for compounds exhibiting the biological activity of cyanocobalamin (cyanocob(III)alamin); the antianemia factor of liver extract that contains cobalt, a cyano group, and corrin in a cobamide structure. Several substances with similar formulas and with the characteristic hematinic action have been isolated and designated: B12a, hydroxocobalamin; B12b, aquacobalamin; B12c, nitritocobalamin; B12r, cob(II)alamin; B12s, cob(I)alamin; B12III, factors A and V1a (cobyric acid) and pseudovitamin B12. Vitamins B12a and B12b are known to be tautomeric compounds; B12b has been obtained from cultures of Streptomyces aureofaciens; B12c has been obtained from cultures of Streptomyces griseus and is distinguishable from B12 by differences in its absorption spectrum. The physiologically active v. B12 coenzymes are methylcobalamin and deoxyadenosinecobalamin. A deficiency of v. B12 is often associated with certain methylmalonic acidurias. SYN: animal protein factor, antianemic factor, antipernicious anemia factor (1) , erythrocyte maturation factor, maturation factor, methylcobalamin. v. BT SYN: carnitine. v. Bx SYN: p-aminobenzoic acid. v. B complex a pharmaceutical term applied to drug products containing a mixture of the B vitamins, usually B1, B2, B3, B5, and B6. v. Bc conjugase an enzyme catalyzing the hydrolysis of the pteroylpolyglutamic acids to pteroylmonoglutamic acid, with consequent increase in v. activity; v. Bc is an obsolete term for folic acid. v. B12 with intrinsic factor concentrate a combination of v. B12 with suitable preparations of the mucosa of the stomach or intestine of domestic animals used for food by humans. v. C SYN: ascorbic acid. coagulation v. obsolete term for v. K. v. D generic descriptor for all steroids exhibiting the biologic activity of ergocalciferol or cholecalciferol, the antirachitic vitamins popularly called the “sun-ray vitamins.” They promote the proper utilization of calcium and phosphorus, thereby producing growth, together with proper bone and tooth formation, in young children; the sulfate, a water-soluble conjugate, is found in the aqueous phase of human milk; v. D1 is a 1:1 mixture of lumisterol and v. D2. v. D2 SYN: ergocalciferol. v. D3 SYN: cholecalciferol. v. E 1. SYN: α-tocopherol. 2. generic descriptor of tocol and tocotrienol derivatives possessing the biologic activity of α-tocopherol; contained in various oils (wheat germ, cotton seed, palm, rice) and whole grain cereals where it constitutes the nonsaponifiable fraction; also contained in animal tissue (liver, pancreas, heart) and lettuce; deficiency produces resorption or abortion in female rats and sterility in males. SYN: antisterility factor, antisterility v., fertility v.. v. F term sometimes applied to the essential unsaturated fatty acids, linoleic, linolenic, and arachidonic acids. fat-soluble vitamins those vitamins, soluble in fat solvents (nonpolar solvents) and relatively insoluble in water, marked in chemical structure by the presence of large hydrocarbon moieties in the molecule; e.g., vitamins A, D, E, K. fertility v. SYN: v. E (2) . v. G obsolete term for riboflavin. v. H SYN: biotin. [Ger, H for Haut, skin] v. K generic descriptor for compounds with the biologic activity of phylloquinone; fat-soluble, thermostable compounds found in alfalfa, hog liver, fish meal, and vegetable oils, essential for the formation of normal amounts of prothrombin. SYN: antihemorrhagic factor, antihemorrhagic v.. v. K1, v. K1(20) SYN: phylloquinone. v. K2, v. K2(30) SYN: menaquinone-6. v. K3 SYN: menadione. v. K4 SYN: menadiol diacetate. v. K5 an antihemorrhagic v.. v. K2(35) SYN: menaquinone-7. microbial v. a substance necessary for the growth of certain microorganisms, e.g., biotin, p-aminobenzoic acid. v. P a mixture of bioflavonoids extracted from plants (especially citrus fruits). It reduces the permeability and fragility of capillaries and is useful in the treatment of certain cases of purpura that are resistant to v. C therapy. SEE ALSO: hesperidin, quercetin, rutin. SYN: capillary permeability factor, citrin, permeability v.. permeability v. SYN: v. P. v. PP SYN: nicotinic acid. v. U term given to a factor in fresh cabbage juice that encourages the healing of peptic ulcer, (3-amino-3-carboxypropyl)dimethylsulfonium chloride, a methionine derivative.

vitellarium (vit′el-lar′e-um)
In cestodes and trematodes, a common chamber receiving vitelline (yolk) material from the two vitelline ducts; the yolk material then passes into the ootype to surround the ovum with nutritive vitelline granules that are enclosed by a characteristically formed eggshell. SYN: vitelline reservoir.

vitelliform (vi-tel′i-form)
Relating to or resembling the yolk of an egg.


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