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

avidity
(ә-vid´ĭ-te) eagerness, or a strong attraction for something. in immunology, an imprecise measure of the strength of antigen-antibody binding based on the rate at which the complex is formed.

avirulence
(a-vir´u-lәns) lack of virulence of an infectious agent. adj., avir´ulent., adj.

avitaminosis
(a-vi″tә-mĭ-no´sis) hypovitaminosis.

avobenzone
(av″o-ben´zōn) a sunscreen that absorbs light in the UVA range.

avocational
(av″o-ka´shәn-әl) pertaining to leisure time activities.

Avogadro's law
(ah-vo-gahd´rōz) equal volumes of perfect gases at the same temperature and pressure contain the same number of molecules.

Avogadro's number
(N) (NA) the number of molecules in one mole of a substance: 6.023 × 1023.

avoidance
(ә-void´әns) a conscious or unconscious defense mechanism consisting of refusal to encounter situations, activities, or objects that would produce conflict.

avoidant
(ә-void´әnt) characterized by avoidance or moving away from something.

avoidant personality disorder
a personality disorder marked by extreme shyness and sensitivity to rejection. Because of this sensitivity, the person becomes socially withdrawn and forms relationships only with those willing to give uncritical acceptance. The self-esteem of such a person is naturally low. Fear of embarrassment prevents the patient from...

avoirdupois weight
(av″әr-dә-poiz´) (av-wahr″doo-pwah´) a system of weights based on pounds and ounces, widely used in English-speaking countries for commodities other than drugs, precious stones, and precious metals.

avulsed tooth
a tooth that has been traumatically dislocated and may be salvageable for reimplantation.

avulsion
(ә-vul´shәn) the tearing away of a structure or part either accidentally or surgically.

avulsion fracture
separation of a small fragment of bone cortex at the site of attachment of a ligament or tendon.

awareness
(ә-wār´nәs) consciousness. sensory awareness the ability to receive and differentiate sensory stimuli.

Axenfeld anomaly
(ahk´sәn-felt″) a developmental anomaly characterized by a circular opacity of the posterior peripheral cornea, and caused by an irregularly thickened, malpositioned Schwalbe ring.

Axenfeld syndrome
(ahk´sәn-felt″) Axenfeld anomaly accompanied by glaucoma and defective development of the corneoscleral trabecular meshwork and other angle structures.

axenic
(a-zen´ik) not contaminated by or associated with any foreign organisms; used in reference to pure cultures of microorganisms or to germ-free animals.

axial compression fracture
fracture of a vertebra by excessive vertical force, so that pieces of it move out in horizontal directions, often injuring the spinal cord; it usually occurs in the thoracic or lumbar region as a result of flexion. Called also burst fracture.

axial fusiform cataract
anterior and posterior polar cataracts joined with threadlike opacities extending axially through the lens; called also spindle cataract.

axial hiatal hernia
sliding hiatal hernia.

axial pattern flap
a myocutaneous flap containing an artery in its long axis.

axial plate
primitive streak.

Axid
(ak´sid) trademark for preparations of nizatidine, an antagonist of histamine H2 receptors used to inhibit gastric acid secretion.

axilla
(ak-sil´ә) pl. axil´lae the pyramidal region between the upper thoracic wall and the upper limb, its base formed by the skin and apex bounded by the approximation of the clavicle, coracoid process, and first rib; it contains axillary vessels, the brachial plexus of nerves, many lymph nodes and vessels, and lo...

axillary
(ak´sĭ-lar″e) of or pertaining to the armpit.

axillary artery
origin, continuation of subclavian artery; branches, subscapular branches, and superior thoracic, thoracoacromial, lateral thoracic, subscapular, and anterior and posterior circumflex humeral arteries; distribution, upper limb, armpit, chest, shoulder.

axillary crutch
any of several types of crutches that have a long, rigid vertical structure, a short padded horizontal bar that fits under the armpit, and another short bar at waist level that is used as a hand grip.

axillary dissection
axillary lymph node dissection surgical removal of axillary lymph nodes, done as part of radical mastectomy.

axillary glands
lymph nodes in the axilla (armpit).

axillary nerve
origin, posterior cord of brachial plexus (C5–C6); branches, lateral superior cutaneous nerve of arm and muscular branches; distribution, deltoid and teres minor muscles, skin on back of arm; modality, motor and general sensory.

axillary region
the area of the upper chest surrounding the armpit (axilla), on the outer side of the pectoral region.

axillary vein
the venous trunk of the upper limb; it begins at the lower border of the teres major muscle by junction of the basilic and brachial veins, and at the lateral border of the first rib is continuous with the subclavian vein.

axillofemoral bypass
insertion of a vascular prosthesis or section of saphenous vein from the axillary artery to the ipsilateral femoral artery to relieve lower limb ischemia in patients in whom normal anatomic placement of a graft is contraindicated, as by abdominal infection or aortic aneurysm.

axillopopliteal bypass
insertion of a vascular prosthesis from the axillary artery to the popliteal artery to relieve lower limb ischemia in patients in whom the femoral artery is unsuitable for axillofemoral bypass.

axis
(ak´sis) pl. ax´es a line through a center of a body, or about which a structure revolves. the second cervical vertebra. adj., ax´ial., adj. Axis. (A), (Top) seen from the side; (bottom) seen from above. (B), Position of the axis (red), immediately below the atlas.&...

axis deviation
an axis shift in the frontal plane, as seen on an electrocardiogram. There are three types: Left, from −30° to −90°; Right, from +90° to +180°; and Undetermined, which may be either extreme left or extreme right, from −90° to +180°.

axis of heart
a line passing through the center of the base of the heart to the apex.

axoaxonic
(ak″so-ak-son´ik) referring to a synapse between the axon of one neuron and the axon of another.

axoaxonic synapse
one between the axon of one neuron and the axon of another neuron.

axodendritic
(ak″so-den-drit´ik) referring to a synapse between the axon of one neuron and dendrites of another.

axodendritic synapse
one between the axon of one neuron and the dendrites of another.

axodendrosomatic synapse
one between the axon of one neuron and the dendrites and body of another.

axolemma
(ak-so-lem´ә) the surface membrane of an axon.

axon
(ak´son) the process of a nerve cell along which impulses travel away from the cell body. It branches at its termination, forming synapses at other nerve cells or effector organs. Many axons are covered by a myelin sheath formed from the cell membrane of a glial cell. adj., ax´onal., adj.

axon reflex
a reflex resulting from a stimulus applied to one branch of a nerve, which sets up an impulse that moves centrally to the point of division of the nerve, where it is reflected down the other branch to the effector organ.

axon wave
A wave.

axonal neuropathy
axonopathy.

axonapraxia
(ak″son-ә-prak´se-ә) neurapraxia.

axoneme
(ak´so-nēm) the central core of a cilium or flagellum, consisting of a central pair of microtubules surrounded by nine other pairs.

axonopathy
(ak″sә-nop´ә-the) a disorder disrupting the normal functioning of the axons.

axonotmesis
(ak″son-ot-me´sis) nerve injury characterized by disruption of the axon and myelin sheath but with preservation of the connective tissue fragments, resulting in degeneration of the axon distal to the injury site; regeneration of the axon is spontaneous and of good quality.

axoplasm
(ak´so-plaz″әm) the cytoplasm of an axon. adj., axoplas´mic., adj.

axosomatic
(ak″so-so-mat´ik) referring to a synapse between the axon of one neuron and the cell body of another.

axosomatic synapse
one between the axon of one neuron and the body of another.

Ayer-Tobey test
Tobey-Ayer test.

Ayerza disease
(ah-yār´sah) a form of polycythemia vera marked by chronic cyanosis, dyspnea, bronchitis, bronchiectasis, enlargement of the liver and spleen, hyperplasia of bone marrow, and sclerosis of the pulmonary artery.

Ayerza syndrome
(ah-yār´sah) pulmonary hypertension with dilatation of the pulmonary arteries, related to disease of the lungs.

ayurveda
(i-yur´ved-ә) (i″yәr-va´dә) the classical system of medicine founded in the Indus valley civilization as oral tradition 5000 years ago and currently practiced in India. It is distinguished by its emphasis on balance with the environment and interpersonal communication and is base...

azatadine
(ә-zat´ә-dēn) an antihistamine with sedative and anticholinergic effects; used as the maleate 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, admin...

azathioprine
(az″ә-thi´o-prēn) a mercaptopurine derivative used as an immunosuppressant for prevention of transplant rejection in organ transplantation; as a disease-modifying antirheumatic drug for treatment of severe, progressive rheumatoid arthritis unresponsive to other agents; and for treatment of a number of autoimm...

azelaic acid
(az″ә-la´ik) a dicarboxylic acid occurring in whole grains and animal products; it has antibacterial effects on both aerobic and anaerobic organisms, particularly Propionibacterium acnes and Staphylococcus epidermidis, normalizes keratinization, and has a cytotoxic effect on malignant or hyperactive melanocytes; a...

azelastine
(ә-zel´ә-stēn) an antihistamine used intranasally as the hydrochloride salt in treatment of hay fever and topically to the conjunctiva in treatment of allergic conjunctivitis.

Azelex
(az´ә-leks) trademark for a preparation of azelaic acid, used for treating acne.

azeotrope
(a´ze-o-trōp″) a mixture of two substances that has a constant boiling point and cannot be separated by fractional distillation. adj., azeotrop´ic., adj.

azithromycin
(az-ith″ro-mi´sin) a macrolide antibiotic derived from erythromycin, effective against a wide range of gram-positive, gram-negative, and anaerobic bacteria; administered orally or intravenously.

azo group
the bivalent radical, sbondNdbondNsbond.

azoospermia
(a-zo″ә-spur´me-ә) lack of live spermatozoa in the semen; see also aspermatogenesis.

Azorean disease
(a-zor´e-әn) Machado-Joseph disease.

azotemia
(az″o-te´me-ә) an excess of nitrogenous waste products in the blood. (This is the most precise name for the condition, although in the literature it is commonly referred to as uremia; for more detalis, see that term.) adj., azote´mic., adj.

azotorrhea
(az″o-tә-re´ә) discharge of excessive quantities of nitrogenous matter in the stools.

azoturia
(az″o-tu´re-ә) an excess of urea or other nitrogen compounds in the urine.

AZT
zidovudine.

aztreonam
(az´tre-o-nam″) a narrow-range antibiotic effective against aerobic gram-negative bacteria; used for the treatment of infections caused by susceptible organisms. Administered intravenously or intramuscularly.

Azulfidine
(a-zul´fĭ-dēn) trademark for a preparation of sulfasalazine, used in the treatment of inflammatory bowel disease and rheumatoid arthritis.

azure
(azh´әr) one of three metachromatic basic dyes (azures A, B, and C).

azuresin
(azh″u-rez´in) a complex combination of azure A dye and carbacrylic cation–exchange resin used as a diagnostic aid in detection of gastric secretion.

azurophil
(azh´u-ro-fil) a tissue constituent staining with azure or a similar blue aniline dye.

azurophil granule
azurophilic granule a type of coarse reddish granule containing that stains easily with azure dyes and is found in the promyelocyte; it contains numerous compounds that are antimicrobial, including myeloperoxidase.

azurophilic
(azh″u-ro-fil´ik) staining with azure or similar blue aniline dyes.

azygogram
(az´ĭ-go-gram) the film obtained by azygography.

azygography
(az″ĭ-gog´rә-fe) radiography of the azygous venous system.

azygos
(az´ĭ-gәs) (ә-zi´gәs) any unpaired part, as the azygos vein. azygous.

azygos lobe
a small anomalous lobe at the apex of the right lung, produced when the azygos vein arches over the upper part of the lung instead of at the hilus and presses deeply into the lung to form a fissure that isolates tissue.

azygos vein
a vein beginning in the abdomen as a continuation of the ascending lumbar vein; it and its tributaries serve as vessels for the return of blood from the thorax to the superior vena cava. The azygos vein also serves as a connecting link, through the ascending lumbar vein, between the venae cavae returning blood from above ...

azygous
(az´ĭ-gәs) (ә-zi´gәs) having no fellow; unpaired. Called also azygos.

BA
Bachelor of Arts.

Ba
barium.

Baastrup disease
(bah´stroop) Baastrup syndrome (bah´stroop) kissing spines.

Babès-Ernst granule
metachromatic granule.

Babesia
(bә-be´ze-ә) a genus of protozoa found as parasites in red blood cells and transmitted by ticks; its numerous species include B. bige´mina, B. bo´vis, B. ma´jor, and B. micro´ti, and cause babesiosis in wild and domestic animals and sometimes humans.

babesiosis
(bә-be″ze-o´sis) a group of tickborne diseases due to infection with protozoa of the genus Babesia, usually seen in wild or domestic animals as a type of anemia; it may spread to humans as a zoonosis characterized by a malarialike fever with chills, sweats, myalgia, nausea and vomiting, hemolytic anemia, and an en...

Babinski phenomenon
(bә-bin´ske) Babinski reflex (bә-bin´ske) a reflex action of the toes, normal during infancy but abnormal after 12 to 18 months of age; after locomotion begins, it is indicative of abnormalities in the motor control pathways leading from the cerebral cortex and is widely used as a diagnostic ...

Babinski sign
loss or lessening of the Achilles tendon reflex in sciatica: this distinguishes it from hysterical sciatica. a misnomer for Babinski reflex. in hemiplegia, the contraction of the platysma muscle in the healthy side is more vigorous than on the affected side, as seen in opening the mouth, whistling, b...

Babinski syndrome
(bә-bin´ske) Babinski-Vaquez syndrome (bә-bin´ske vah-ka´) the association of cardiac and arterial disorders with chronic syphilitic meningitis, tabes dorsalis, paralytic dementia, and other late syphilitic manifestations.

Babinski test
Babinski sign (def. 4).

Babinski toe sign
Babinski reflex.

Babinski-Fröhlich syndrome
(bә-bin´ske frur´lik) adiposogenital dystrophy.

Babinski-Nageotte syndrome
(bә-bin´ske nah-zhot´) a syndrome due to multiple lesions affecting the medullary pyramid and sensory tracts, the cerebellar peduncle, and the reticular formation, and marked by contralateral hemiplegia and hemianesthesia (usually only of the pain and temperature senses), ipsilateral hemiasynergia, hemiataxi...

Babinski-Weil test
(for disease of the labyrinth) the patient, with eyes shut, walks forward and backward ten times; with labyrinthine disease there will be deviation from the straight path, bending to one side when walking forward and to the other when walking backward.