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Medical Dictionary


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risus (ri′sus)
Laughter. [laughter] r. caninus (ri′sus ka-ni′nus) the semblance of a grin caused by facial spasm, seen especially in tetanus but also in some kinds of poisoning. SYN: canine spasm, r. sardonicus, sardonic grin, trismus sardonicus. [L. r., laugh + caninus, doglike] r. sardonicus (sar-don′i-kus) SYN: r. caninus. [L. r., laughter, + sardonicus, fr. G. sardanios, scornful, infl. by sardonios, Sardinian, ref. to effects of Strychnos nux-vomica, poisonous herb fr. Sardinia]

Ritgen
Ferdinand A.M.F. von, German obstetrician, 1787–1867. See R. maneuver.

ritodrine (ri′to-dren)
A sympathomimetic agent with β2-adrenergic stimulant actions, used as a uterine relaxant.

Ritter
Johann W., German physicist, 1776–1810. See R. opening tetanus, R.-Rollet phenomenon.

ritual (rich′oo-al)
In psychiatry and psychology, any psychomotor activity ( e.g., morbid handwashing) performed by a person to relieve anxiety or forestall its development; typically seen in obsessive-compulsive disorder. [L. ritualis, fr. ritus, rite]

rituximab (rit-uks′im-ab)
Monoclonal antibody used in the treatment of non-Hodgkin lymphoma.

rivalry (ri′val-re)
Competition between two or more individuals or entities for the same object or goal. [L. rivalis, competitor, rival] binocular r. alteration in perception of portions of the visual field when the two eyes are simultaneously and rapidly exposed to targets containing dissimilar colors or borders. r. of retina simultaneous excitation of corresponding retinal areas of each eye by stimuli that differ in size, color, shape, or luminance, making fusion impossible. sibling r. jealous competition among children, especially for the attention, affection, and esteem of their parents; by extension, a factor in both normal and abnormal competitiveness throughout life.

Rivea corymbosa (riv′e-a ko-rim-bo′sa)
Mexican bindweed, a plant of the family Convolvulaceae, the seeds of which were used in ceremonies by Aztec Indians in Mexico and contain lysergic acid amide, isolysergic acid, lysergic acid monoethylamide, chanoclavine, and other indole alkaloids; several hundred seeds must be ingested to produce hallucinatory and euphoric effects. SYN: morning glory (2) .

Riverius
See Rivière.

Rivero-Carvallo
José Manuel, Mexican cardiologist, *1905. See Carvallo sign, Rivero-Carvallo effect.

Rivers
William H., English physician, 1864–1922. See R. cocktail.

Rivière, Riverius
Lazare (Lazarus), French physician, 1589–1655. See R. salt.

Rivinus (Latin form of Bachmann)
August Q., German anatomist, 1652–1723. See R. canals, under canal, R. ducts, under duct, R. gland, R. incisure, R. membrane, R. notch.

rivus lacrimalis (ri′vus lak-ri-ma′lis) [TA]
SYN: lacrimal pathway. [L. rivus, stream, + Mediev. L. lacrimalis, fr. L. lacrima, a tear]

riziform (riz′i-form)
Resembling rice grains. [Fr. riz, rice]

RLL
Abbreviation for right lower lobe (of lung).

RLQ
Abbreviation for right lower quadrant (of abdomen).

RMA
Abbreviation for right mentoanterior position.

RML
Abbreviation for right middle lobe (of lung).

RMP
Abbreviation for right mentoposterior position.

RMT
Abbreviation for right mentotransverse position.

RMV
Abbreviation for respiratory minute volume.

R.N.
Abbreviation for registered nurse.

Rn
Symbol for radon.

RNA
Abbreviation for ribonucleic acid.For terms bearing this abbreviation, see subentries under ribonucleic acid.

RNase
Abbreviation for ribonuclease.For terms bearing this abbreviation, see subentries under ribonuclease.

RNase D
Abbreviation for ribonuclease D.

RNA splicing
SYN: splicing (2) .

RNP
Abbreviation for ribonucleoprotein.

ROA
Abbreviation for right occipitoanterior position.

Roach
F. Ewing, U.S. prosthodontist, 1868–1960. See R. clasp.

Roaf
R. See R. syndrome.

Robert
Heinrich, L.F., German gynecologist, 1814–1878. See R. pelvis.

Roberts
J.B., 20th century U.S. physician. See R. syndrome.

Robertshaw
Frank L., 20th century English anesthesiologist. See R. tube.

Robertson
See Argyll R..

Robin
Pierre, French pediatrician, 1867–1950. See Pierre R. syndrome.

Robin
Charles P., French physician, 1821–1885. See Virchow-R. space.

Robinow
Meinhard, U.S. physician, *1909. See R. dwarfism, R. syndrome.

Robinson
Brian F., 20th century British cardiologist. See R. index.

Robison
Robert, English chemist, 1884–1941. See R. ester, R. ester dehydrogenase, R.-Embden ester.

Robles
Rudolfo (Valverde), Guatemalan dermatologist, 1878–1939.

robotic (ro-bot′ik)
Pertaining to or characteristic of a robot, an automatic mechanical device designed to duplicate a human function without direct human operation. [Czech robot, robot, fr. robota, drudgery, + -ic]

Robson
See Mayo-R..

robustness (ro-bust′ness)
In statistics, the degree to which the probability of drawing a wrong conclusion from the test result is not seriously affected by moderate departures from the assumptions implicit in the model on which the test is based. [L. robustus, hale, strong, fr. robur, oak, hard, strong]

ROC
Acronym for receiver operating characteristic, an analytic expression of diagnostic accuracy. See R. curve.

roccellin (rok′sel-in) [C.I. 15620]
SYN: archil.

Rochalimaea (ro-cha-li′ma-a)
Former name for Bartonella. [H. da Rocha-Lima, Brazilian microbiologist] R. henselae See Bartonella henselae. R. quintana See Bartonella quintana.

rod (rod)
1. A slender cylindric structure or device. 2. The photosensitive, outward-directed process of a rhodopsin-containing r. cell in the external granular layer of the retina; many millions of such rods, together with the cones, form the photoreceptive layer of rods and cones. SYN: r. cell of retina. [A.S. r.] analyzing r. a device used with a surveyor to determine the relative positions of parallel surfaces and undercuts when designing removable partial dentures. Auer rods SYN: Auer bodies, under body. basal r. SYN: costa (2) . Corti rods SYN: pillar cells, under cell. enamel rods SYN: prismata adamantina, under prisma. germinal r. SYN: sporozoite. Maddox r. a glass r., or a series of parallel glass rods, that converts the image of a light source into a streak of light perpendicular to the axis of the r.. The position of this streak in relation to the image of the light source seen by the fellow eye indicates the presence and amount of heterophoria. surgical r. a cylindric implant, usually composed of metal, used to align and internally fix fractures of long bones. SEE ALSO: nail, pin.

Rodentia (ro-den′she-a)
The rodents; the largest order of placental mammals (class Eutheria), all possessing one pair of chisel-like upper incisors for gnawing and flat-crowned premolars and molars for grinding; it includes the mice, rats, guinea pigs, squirrels, beavers, and many more. [Mod. L., fr. L. rodo, pres. p. rodens, to gnaw]

rodenticide (ro-den′ti-sid)
An agent lethal to rodents. [rodent + L. caedo, to kill]

Roentgen
Wilhelm K., German physicist and Nobel laureate, 1845–1923. Discovered x-rays in November, 1895; awarded Nobel Prize in Physics in 1901 for his discovery. See r., r. ray.

roentgen (R, r) (rent′gen, rent′chen)
The international unit of exposure dose for x-rays or gamma rays; that quantity of radiation that will produce in 1 cc or 0.001293 g of air at STP, 2.08 × 109 ions of both signs, each totaling 1 electrostatic unit (e.s.u.) of charge; in the MKS system this is 2.58 × 10−4 coulombs per kg of air. [W. K. R.] r.-equivalent-man (rem) a unit of dose equivalent to that quantity of ionizing radiation of any type that produces in humans the same biologic effect as 1 rad of x-rays or gamma rays; the number of rems is equal to the absorbed dose, measured in rads, multiplied by the quality factor of the radiation in question. 100 rem = 1 Sv. r.-equivalent-physical obsolete unit of measurement; that quantity of ionizing radiation of any kind that, upon absorption by living tissue, produces an energy gain per gram of tissue equivalent to that produced by 1 rad of x-rays or gamma-rays. See rad.

roentgenkymogram (rent′gen-ki′mo-gram)
A record of the heart's movements taken with the roentgenkymograph.

roentgenkymograph (rent′gen-ki′mo-graf)
An apparatus for recording the movements of the heart and great vessels or of the diaphragm on a single film. It consists of a lead sheet called the grid in which are cut horizontal or vertical slits, typically less than 1 mm wide, spaced 1–2 cm apart. During an x-ray exposure lasting as long as several cardiac or respiratory cycles, the grid or the film is moved vertically to record cardiac motion or horizontally for diaphragm motion.

roentgenkymography (rent′gen-ki-mog′ra-fe)
An obsolete technique involving the recording of movements of the heart by means of the roentgenkymograph.

roentgenogram (rent′gen-o-gram)
SYN: radiograph.

roentgenograph (rent′gen-o-graf)
SYN: radiograph.

roentgenography (rent′ge-nog′ra-fe)
SYN: radiography.

roentgenologist (rent′gen-ol′o-jist)
A person skilled in the diagnostic or therapeutic application of roentgen rays; a radiologist.

roentgenology (rent′gen-ol′o-je)
The study of roentgen rays in all their applications. Radiology is the preferred term in the context of medical imaging.

roentgenometer (rent′ge-nom′e-ter)
SYN: radiometer.

roentgenometry (rent-ge-nom′e-tre)
Measurement of an administered therapeutic or diagnostic dose and the penetrating power of x-rays. SYN: x-ray dosimetry.

roentgenoscope (rent′gen-o-scop)
Obsolete term for fluoroscope.

roentgenoscopy (rent-gen-os′ko-pe)
Obsolete term for fluoroscopy.

roentgenotherapy (rent′gen-o-thar′a-pe)
Obsolete term for radiotherapy.

roetheln
See röteln.

Roger
Georges Henri, French physiologist, 1860–1946. See R. reflex.

Roger
Henri L., French physician, 1809–1891. See R. disease, R. murmur, bruit de R., maladie de R..

Rogers
Oscar H., U.S. physician, 1857–1941. See R. sphygmomanometer.

Rohr
Karl, Swiss embryologist and gynecologist, *1863. See R. stria.

Röhrer index
See under index.

Rokitansky
Karl Freiherr von, Austrian pathologist, 1804–1878. See R. disease, R. hernia, R.-Aschoff sinuses, under sinus, Mayer-R.-Küster-Hauser syndrome.

rolandic (ro-lan′dik)
Relating to or described by Luigi Rolando.

Rolando
Luigi, Italian anatomist, 1773–1831. See R. angle, R. area, R. cells, under cell, R. column, rolandic epilepsy, R. gelatinous substance, R. tubercle, fissure of R..

role (rol)
The pattern of behavior that a person exhibits in relationship to significant persons in his or her life; it has its roots in childhood and is influenced by significant people with whom the person has or had primary relationships. [Fr.] complementary r. a r. in which the behavior pattern conforms with the expectations and demands of other people. gender r. the public presentation of gender identity; specifically, everything a person says and does that signals to others or to the self that one is male or female (or androgynous). See sex r., gender identity. noncomplementary r. a r. that does not conform with the expectations and demands of other people. sex r. specifically, the pattern of behavior and thought related to sex organs and procreation; but more generally, behavior and thought that is stereotypically classified as belonging to either one sex or the other. See gender r.. sick r. in medical sociology, the familially or culturally accepted behavior pattern or r. which one is permitted to exhibit during illness or disability, including sanctioned absence from school or work and a submissive, dependent relationship to family, health care personnel, and significant others.

role-playing
A psychotherapeutic method used in psychodrama to understand and treat emotional conflicts through the enactment or reenactment of stressful interpersonal events. See psychodrama.

rolitetracycline (ro′li-tet-ra-si′klen)
A more soluble and less irritating derivative of tetracycline; uses and effectiveness are similar to those of tetracycline, and it may be administered intravenously or intramuscularly, which makes it useful when oral administration of a tetracycline is impossible or impracticable.




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