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Medical Dictionary - Dictionary of Medicine and Human Biology

Medical Dictionary


excitor (ek-si′ter, -tor)
SYN: stimulant (2) .

excitosecretory (ek-si′to-se-kre′to-re)
Stimulating to secretion.

excitotoxic (ek-si′-to-tok-sik)
Possessing the property of exciting and then poisoning cells or tissues; examples include nerve injury and death produced by glutamate. [excite + G. toxikon, poison]

excitotoxins (ek-si′to-toks′ins)
Toxins that bind to certain receptors ( e.g., certain glutamate receptors) and may cause neuronal cell death; e. may be involved in brain damage associated with strokes.

exclave (eks-klav′)
An outlying, detached portion of a gland or other part, such as the thyroid or pancreas; an accessory gland. [L. ex, out, + -clave (in enclave)]

exclusion (eks-kloo′zhun)
A shutting out; disconnection from the main portion. [L. ex- cludo, pp. -clusus, to shut out] allelic e. in each cell of an individual heterozygous at an autosomal locus, the non-preferential suppression of the phenotypic manifestation of one or other of the alleles; the phenotype of the body is thus mosaic. Cf.:lyonization. e. of pupil SYN: seclusion of pupil.

exclusive provider organization (EPO)
A managed care plan in which enrollees must receive their care from affiliated providers; treatment provided outside the approved network must be paid for by the patients. SEE ALSO: managed care.

exconjugant (eks-kon′joo-gant)
A member of a conjugating pair of protozoan ciliates after separation and prior to the subsequent mitotic division of each of the exconjugants. SEE ALSO: conjugant, conjugation (3) . [ex- + L. conjugo, to join]

excoriate (eks-ko′re-at)
To scratch or otherwise strip off the skin by physical means.

excoriation (eks-ko′re-a′shun)
A scratch mark; a linear break in the skin surface, usually covered with blood or serous crusts. [L. excorio, to skin, strip, fr. corium, skin, hide] neurotic e. repeated self-induced e., with or without underlying skin lesions, associated with compulsive or neurotic behavioral problems.

excrement (eks′kre-ment)
Waste matter or any excretion cast out of the body; e.g., feces. [L. ex- cerno, pp. -cretus, to separate]

excrementitious (eks′kre-men-tish′us)
Relating to any excrement.

excrescence (eks-kres′ens)
Any outgrowth from a surface. [L. ex- cresco, pp. -cretus, to grow forth] Lambl excrescences small pointed projections from the edges of the aortic cusps of unknown significance.

excreta (eks-kre′ta)
SYN: excretion (2) . [L. neut. pl. of excretus, pp. of ex-cerno, to separate]

excrete (eks-kret′)
To separate from the blood and cast out; to perform excretion.

excretion (eks-kre′shun)
1. The process whereby the undigested residue of food and the waste products of metabolism are eliminated, material is removed to regulate the composition of body fluids and tissues, or substances are expelled to perform functions on an exterior surface. 2. The product of a tissue or organ that is material to be passed out of the body. SYN: excreta. Cf.:secretion. [see excrement]

excretory (eks′kre-to-re)
Relating to excretion.

excursion (eks-ker′zhun)
Any movement from one point to another, usually with the implied idea of returning again to the original position. lateral e. movement of the mandible to the right or left side. protrusive e. movement of the mandible to a position forward of the centric position. retrusive e. the slight backward and return movement of the mandible between the position of closure and a slightly posterior position.

excycloduction (ek-si-klo-duk′shun)
A cycloduction in which the upper pole of the cornea is rotated outward (laterally). [ex- + cyclo- + L. duco, pp. ductus, to lead]

excyclophoria (ek-si-klo-fo′re-a)
A cyclophoria in which the upper poles of each cornea tend to rotate laterally. [ex- + cyclo- + G. phora, a carrying]

excyclotorsion (eks′si-klo-tor′shun)
SYN: extorsion (1) . [ex- + cyclo- + L. torqueo, pp. torsus, to twist]

excyclotropia (eks′si-klo-tro′pe-a)
A cyclotropia in which the upper poles of the corneas are rotated outward (laterally) relative to each other. [ex- + cyclo- + G. trope, a turning]

excyclovergence (ek-si-klo-ver′jens)
Rotation of the upper pole of each cornea outwards. [ex- + cyclo- + L. vergo, to bend, incline]

excystation (ek-sis-ta′shun)
Removal from a cyst; denoting the action of certain encysted organisms in escaping from their envelope.

exduction (eks-duk′shun)
SYN: lateroduction. [ex- + L. duco, pp. ductus, to lead]

exemia (ek-se′me-a)
A condition, as in shock, in which a considerable portion of the blood is removed from the main circulation but remains within blood vessels in certain areas where it is stagnant. [G. ex, out of, + haima, blood]

exencephalia (eks′en-se-fa′le-a)
SYN: exencephaly.

exencephalic (eks′en-se-fal′ik)
Relating to exencephaly. SYN: exencephalous.

exencephalocele (eks′en-sef′a-lo-sel)
Herniation of the brain. [ex, out, + G. enkephalos, brain, + kele, tumor]

exencephalous (eks-en-sef′a-lus)
SYN: exencephalic.

exencephaly (eks-en-sef′a-le)
Condition in which the skull is defective with the brain exposed or extruding. SYN: exencephalia. [G. ex, out, + enkephalos, brain]

exenteration (eks-en-ter-a′shun)
Removal of internal organs and tissues, usually radical removal of the contents of a body cavity. SYN: evisceration (1) . [G. ex, out, + enteron, bowel] anterior pelvic e. removal of the urinary bladder, lower parts of the ureter, vagina, uterus, adnexa, and adjacent lymph nodes; a urinary diversion is necessary. orbital e. removal of the entire contents of the orbit. pelvic e. removal of all of the organs and adjacent structures of the pelvis; usually performed to surgically ablate cancer involving urinary bladder, uterine cervix, and rectum. posterior pelvic e. removal of the vagina, uterus, adnexa, rectum, anus, and adjacent lymph nodes; a colostomy is necessary. total pelvic e. removal of the urinary bladder, lower parts of the ureter, vagina, uterus, adnexa, rectum, anus, and adjacent lymph nodes; a colostomy and urinary diversion are necessary. SYN: Brunschwig operation.

exenteritis (eks-en-ter-i′tis)
Inflammation of the peritoneal covering of the intestine. [G. exo, on the outside, + enteritis]

exercise (ek′ser-siz)
1. Active: bodily exertion for the sake of restoring the organs and functions to a healthy state or keeping them healthy. 2. Passive: motion of limbs without effort by the patient. isometric e. e. consisting of muscular contractions without movement of the involved parts of the body. isotonic e. SYN: isotonic contraction. Kegel exercises alternate contraction and relaxation of perineal muscles for treatment of urinary stress incontinence.

exeresis (ek-ser′e-sis)
SYN: excision. [G. exairesis, a taking out, fr. haireo, to take, grasp]

exergonic (ek-ser-gon′ik)
1. Referring to a chemical reaction that takes place with a negative charge in Gibbs free energy. Cf.:endergonic. 2. Any process that can produce work. [exo- + G. ergon, work]

exflagellation (eks-flaj-e-la′shun)
The extrusion of rapidly waving flagellum-like microgametes from microgametocytes; in the case of human malaria parasites, this occurs in the blood meal taken by the proper anopheline vector within a few minutes after ingestion of the infected blood by the mosquito. SYN: polymitus.

exfoliation (eks-fo-le-a′shun)
1. Detachment and shedding of superficial cells of an epithelium or from any tissue surface. 2. Scaling or desquamation of the horny layer of epidermis, which varies in amount from minute quantities to shedding the entire integument. 3. Loss of deciduous teeth following physiological loss of root structure. [Mod. L. fr. L. ex, out, + folium, leaf] e. of lens sheetlike separation of the capsule of the lens; it may occur if the eyes are exposed to intense heat.

exfoliative (eks-fo′le-a-tiv)
Marked by exfoliation, desquamation, or profuse scaling. [Mod. L. exfoliativus]

exhalation (eks-ha-la′shun)
1. Breathing out. SYN: expiration (1) . 2. The giving forth of gas or vapor. 3. Any exhaled or emitted gas or vapor. [L. ex-halo, pp. -halatus, to breathe out]

exhale (eks′hal)
1. To breathe out. SYN: expire (1) . 2. To emit a gas or vapor or odor.

exhaustion (eg-zos′chun)
1. Extreme fatigue; inability to respond to stimuli. 2. Removal of contents; using up of a supply of anything. 3. Extraction of the active constituents of a drug by treating with water, alcohol, or other solvent. [L. ex-haurio, pp. -haustus, to draw out, empty] heat e. a form of reaction to heat, marked by prostration, weakness, and collapse, resulting from severe dehydration.

exhibitionism (ek-si-bish′un-izm)
A morbid compulsion to expose a part of the body, especially the genitals, with the intent of provoking sexual interest in the viewer.

exhibitionist (ek-si-bish′un-ist)
One who engages in exhibitionism.

exhilarant (eg-zil′ar-ant)
Mentally stimulating. [L. ex-hilaro, pp. -atus, pres. p. -ans, to gladden]

existential (eg-zi-sten′shal)
Pertaining to a branch of philosophy, existentialism, concerned with the search for the meaning of one's own existence, that has been extended into e. psychotherapy. [L. existentia, existence]

exitus (eks′i-tus)
An exit or outlet; death. [L. fr. ex-eo, pp. -itus, to go out]

Siegmund, Austrian physiologist, 1846–1926. See Call-E. bodies, under body, E. plexus.

Exterior, external, or outward. SEE ALSO: ecto-. [G. exo, outside]

exoamylase (ek-so-am′il-as)
A glucanohydrolase acting on a glycosidic bond near an end of the polysaccharide; E.G., β-amylase.

exoantigen (ek-so-an′ti-jen)
SYN: ectoantigen.

exocardia (ek-so-kar′de-a)
SYN: ectocardia.

exocrine (ek′so-krin)
1. Denoting glandular secretion delivered to an apical or luminal surface. SYN: eccrine (1) . 2. Denoting a gland that secretes outwardly through excretory ducts. [exo- + G. krino, to separate]

exocyclic (ek-so-si′klik, -sik′lik)
Relating to atoms or groups attached to a cyclic structure but not themselves cyclic; e.g., the methyl group of toluene. Cf.:endocyclic.

exocytosis (ek′so-si-to′sis)
1. The appearance of migrating inflammatory cells in the epidermis. 2. The process whereby secretory granules or droplets are released from a cell; the membrane around the granule fuses with the cell membrane, which ruptures, and the secretion is discharged. SYN: emeiocytosis, emiocytosis. Cf.:endocytosis. [exo- + G. kytos, cell, + -osis, condition]

exodeviation (ek′so-de-ve-a′shun)
1. SYN: exophoria. 2. SYN: exotropia.

exodontia (ek-so-don′she-a)
The branch of dental practice concerned with the extraction of teeth. [exo- + G. odous, tooth]

exodontist (ek-so-don′tist)
One who specializes in the extraction of teeth.

exoenzyme (ek-so-en′zim)
SYN: extracellular enzyme.

exogamy (ek-sog′a-me)
Sexual reproduction by means of conjugation of two gametes of different ancestry, as in certain protozoan species. [exo- + G. gamos, marriage]

exogastrula (eks-o-gas′troo-la)
An abnormal embryo in which the primitive gut has been everted.

exogenetic (ek′so-je-net′ik)
SYN: exogenous.

exogenote (ek-so-je′not)
In microbial genetics, the fragment of genetic material that has been transferred from a donor to the recipient and, being homologous for a region of the recipient's original genome (endogenote), produces in the homologous region a condition analogous to diploidy. [exo + genote]

exogenous (eks-oj′e-nus)
Originating or produced outside of the organism. SYN: ectogenous, exogenetic. [exo- + G. -gen, production]

A hydrolase removing terminal α-1,4-linked d-glucose residues from nonreducing ends of chains, with release of β-d-glucose. SYN: acid maltase, amyloglucosidase, γ-amylase, glucoamylase.

exolever (ek′so-le′ver)
A modified elevator for the extraction of tooth roots. [exo- + L. levare, to raise]

exomphalos (eks-om′fa-lus)
1. Protrusion of the umbilicus. SYN: exumbilication (1) . 2. SYN: umbilical hernia. 3. SYN: omphalocele. [G. ex, out, + omphalos, umbilicus]

exon (ek′son)
A portion of a DNA that codes for a section of the mature messenger RNA from that DNA, and is therefore expressed (“translated” into protein) at the ribosome. [ex- + on]

exon shuffle
The variation in the patterns by which RNA may produce diverse sets of exons from a single gene.

exonuclease (ek-so-noo′kle-as)
A nuclease that releases one nucleotide at a time, serially, beginning at one end of a polynucleotide (nucleic acid); several have been prepared from Escherichia coli, designated e. I, e. II, etc.; e. III, which removes nucleotides from 3′ ends of DNA, is used in DNA sequencing. Cf.:endonuclease.


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