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Medical Dictionary


blennostasis (blen-os′ta-sis)
Rarely used term for diminution or suppression of secretion from the mucous membranes. [blenno- + G. stasis, standing]

blennostatic (blen-o-stat′ik)
Rarely used term for diminishing mucous secretion.

blennuria (ble-noo′re-a)
The excretion of an excess of mucus in the urine. [blenno- + G. ouron, urine]

bleomycin sulfate (ble-o-mi′sin)
An antineoplastic antibiotic obtained from Streptomyces verticillus. Often produces pulmonary fibrosis.

See blepharo-.

blepharadenitis (blef′ar-ad-e-ni′tis)
Inflammation of the meibomian glands or the marginal glands of Moll or Zeis. SYN: blepharoadenitis. [blephar- + G. aden, gland, + -itis, inflammation]

blepharal (blef′a-ral)
Referring to the eyelids.

blepharectomy (blef′a-rek′to-me)
Excision of all or part of an eyelid. [blepharo- + G. ektome, excision]

blepharedema (blef′ar-e-de′ma)
Edema of the eyelids, causing swelling and often a baggy appearance.

blepharitis (blef′a-ri′tis)
Inflammation of the eyelids. [blepharo- + G. -itis, inflammation] b. acarica SYN: demodectic b.. b. angularis inflammation of the lid margins at the angles of the commissure. ciliary b. SYN: b. marginalis. demodectic b. inflammation of the eyelid associated with Demodex folliculorum. SYN: b. acarica. b. follicularis a deep-seated suppurative inflammation of ciliary follicles and the glands of Zeis and Moll of the eyelid. SYN: pustular b.. marginal b. SYN: b. marginalis. b. marginalis inflammation of the margins of the eyelids. SYN: ciliary b., marginal b.. meibomian b. inflammation of the eyelid margin and the meibomian glands. b. parasitica marginal b. due to the presence of lice. SYN: b. phthiriatica, pediculous b.. pediculous b. SYN: b. parasitica. b. phthiriatica SYN: b. parasitica. posterior b. inflammation of eyelid margins characterized by inspissation and occlusion of tarsal glands orifices. pustular b. SYN: b. follicularis. b. rosacea inflammation of the margins of the eyelids in association with acne rosacea. seborrheic b. a common type of chronic inflammation of the margins of the eyelids with erythema and white scales; often with an associated seborrheic dermatitis of scalp and face. b. sicca inflammation of the margins of the eyelids in which the lashes are powdered with dry scales. staphylococcal b. inflammation of the eyelids characterized by brittle hard scales along the base of the eyelashes. b. ulcerosa marginal b. with ulceration.

blepharo-, blephar-
Eyelid. [G. blepharon, an eyelid]

blepharoadenitis (blef′a-ro-ad-e-ni′tis)
SYN: blepharadenitis.

blepharoadenoma (blef′a-ro-ad-e-no′ma)
A tumor or adenoma of a gland of the eyelid. [blepharo- + G. aden, gland, + -oma, tumor]

blepharochalasis (blef′a-ro-kal′a-sis)
A condition in which there is a redundancy of the skin of the upper eyelids so that a fold of skin hangs down, often concealing the tarsal margin when the eye is open. SYN: ptosis adiposa. [blepharo- + G. chalasis, a slackening]

blepharoclonus (blef-ar-ok′lo-nus)
Clonic spasm of the eyelids. [blepharo- + G. klonos, a tumult]

blepharocoloboma (blef′a-ro-kol-o-bo′ma)
SYN: ankyloblepharon. [blepharo- + coloboma]

blepharoconjunctivitis (blef′a-ro-kon-junk-ti-vi′tis)
Inflammation of the palpebral conjunctiva.

blepharodiastasis (blef′a-ro-di-as′ta-sis)
Abnormal separation or inability to completely close the eyelids. [blepharo- + G. diastasis, separation]

blepharokeratoconjunctivitis (blef′a-ro-ker′a-to-kon-junk′ti-vi′tis)
An inflammation involving the eyelids, cornea, and conjunctiva.

blepharon (blef′a-ron)
SYN: eyelid. [G. b., eyelid]

blepharophimosis (blef′a-ro-fi-mo′sis)
Decrease in the width of the palpebral aperture without fusion of lid margins. SYN: blepharostenosis. [blepharo- + G. phimosis, an obstruction]

blepharoplast (blef′a-ro-plast)
SYN: basal body. [blepharo- + G. plastos, formed]

blepharoplastic (blef′a-ro-plas′tik)
Relating to blepharoplasty.

blepharoplasty (blef′a-ro-plast-te)
Any operation for the correction of a defect in the eyelids. [blepharo- + G. plasso, to form]

blepharoplegia (blef′a-ro-ple′je-a)
Paralysis of an eyelid. [blepharo- + G. plege, stroke]

blepharoptosis, blepharoptosia (blef′a-rop′to-sis, -rop-to′se-a)
Drooping of the upper eyelid. SYN: ptosis (2) . [blepharo- + G. ptosis, a falling] b. adiposa b. with accumulation of subcutaneous fat causing skin to hang over the free border of the eyelid. false b. SYN: pseudoptosis.

blepharospasm, blepharospasmus (blef′a-ro-spazm, -spaz′mus)
Involuntary spasmodic contraction of the orbicularis oculi muscle; may occur in isolation or be associated with other dystonic contractions of facial, jaw, or neck muscles; usually initiated or aggravated by emotion, fatigue, or drugs.

blepharostat (blef′a-ro-stat)
SYN: eye speculum. [blepharo- + G. statos, fixed]

blepharostenosis (blef′a-ro-ste-no′sis)
SYN: blepharophimosis. [blepharo- + G. stenosis, a narrowing]

blepharosynechia (blef′a-ro-sin-ek′e-a)
Adhesion of the eyelids to each other or to the eyeball. [blepharo- + G. synecheia, continuity, fr. syn- echo, to hold together]

blepharotomy (blef-a-rot′o-me)
A cutting operation on an eyelid. [blepharo- + G. tome, incision]

blind (blind)
Unable to see; without useful sight. See blindness.

blindness (blind′nes)
1. Loss of the sense of sight; absolute b. connotes no light perception. SEE ALSO: amblyopia, amaurosis. 2. Loss of visual appreciation of objects although visual acuity is normal. 3. Absence of the appreciation of sensation, e.g., taste b.. SYN: typhlosis. change b. failure to observe large changes in the vision field that occur simultaneously with brief disturbances. color b. misleading term for anomalous or deficient color vision; complete color b. is the absence of one of the primary cone pigments of the retina. See protanopia, deuteranopia, tritanopia. cortical b. loss of sight due to an organic lesion in the visual cortex. day b. SYN: hemeralopia. eclipse b. SYN: solar maculopathy. flash b. a temporary loss of vision produced when retinal light-sensitive pigments are bleached by light more intense than that to which the retina is physiologically adapted at that moment. flight b. visual blackout in aviators. SEE ALSO: amaurosis fugax. functional b. apparent loss of vision related to suggestibility. hysterical b. loss of vision or blurring of vision following a psychologically traumatic event such as seeing one's child being killed in an accident. legal b. generally, visual acuity of less than 6/60 or 20/200 using Snellen test types, or visual field restriction to 20° or less in the better eye; the criteria used to define legal b. vary among different groups. letter b. visual agnosia for letters, in which letters are seen but not identified; caused by a lesion in the occipital cortex. mind b. visual agnosia for objects, in which objects are seen but not identified; caused by a lesion in area 18 of the occipital cortex. SYN: object b., psychanopsia, psychic b.. music b. SYN: musical alexia. night b. SYN: nyctalopia. note b. SYN: musical alexia. object b. SYN: mind b.. psychic b. SYN: mind b.. river b. SYN: ocular onchocerciasis. sight b. SYN: asymbolia. sign b. visual agnosia for signs. snow b. severe photophobia secondary to ultraviolet keratoconjunctivitis. solar b. SYN: solar maculopathy. taste b. inability to appreciate gustatory stimuli. text b., word b. SYN: alexia.

blink (blink)
To close and open the eyes rapidly; an involuntary act by which the tears are spread over the conjunctiva, keeping it moist. SYN: wink.

1. A fluid-filled thin-walled structure under the epidermis or within the epidermis (subepidermal or intradermal). 2. To form a b. with heat or some other vesiculating agent. blood b. a b. containing blood; resulting from a pinch or crushing injury. fever b. colloquialism for herpes simplex of the lips. fly b. a cantharidal b. caused by discharge of a vesicating body fluid by certain beetles, particularly members of the family Meloidae which produce cantharidin, e.g., Lytta (Cantharis) vesicatoria, the notorious “Spanish fly”; noncantharidin vesicating fluid is produced by other beetles, such as rove beetles (family Staphylinidae), especially the genus Paederus, whose fluid, on contact with the skin, produces an intensely painful b.. fracture b. superficial epidermolysis that occurs in association, most commonly, with fractures of the leg and ankle and forearm and wrist; etiology represents a combination of excessive swelling and torsional injury to the overlying soft tissues. sucking b. superficial bullous skin lesion on neonate arm probably resultant from vigorous prenatal sucking.

SYN: vesiculation (1) .

bloat, bloating (blot, blot′ing)
1. Abdominal distention from swallowed air or intestinal gas from fermentation. 2. Distention of the rumen of cattle, caused by the accumulation of gases of fermentation, particularly likely to occur when the animals are pastured on rich legume grasses; if unrelieved, the condition may quickly lead to death.

Marcel, French physician, 1885–1925. See B. reaction.

Bruno, Swiss dermatologist, 1878–1933. See B.-Sulzberger disease, B.-Sulzberger syndrome.

block (block)
1. To obstruct; to arrest passage through. 2. A condition in which the passage of an electrical impulse is arrested, wholly or in part, temporarily or permanently. 3. SYN: atrioventricular b.. [Fr. bloquer] alveolocapillary b. the presence of material that impairs the diffusion of gases between the air in the alveolar spaces and the blood in alveolar capillaries; b. can be caused by edema, cellular infiltration, fibrosis, or tumor, and results in undersaturation of peripheral arterial blood with oxygen. antegrade b. SYN: anterograde b.. anterograde b. conduction b. of an impulse traveling anywhere in its ordinary direction, for example, from the sinoatrial node toward the ventricular myocardium. SYN: antegrade b.. arborization b. intraventricular b. supposedly due to widespread blockage in the Purkinje ramifications and manifested in the electrocardiogram by a pattern similar to bundle-branch b. but with complexes of low amplitude. atrioventricular b., AV b. partial or complete b. of electric impulses originating in the atrium or sinus node preventing them from reaching the atrioventricular node and ventricles. In first degree AV b., there is prolongation of AV conduction time (PR interval); in second degree AV b., some but not all atrial impulses fail to reach the ventricles, thus some ventricular beats are dropped; in complete AV b. (third degree), complete atrioventricular dissociation (2) occurs; no impulses can reach the ventricles despite even a slow ventricular rate (under 45/min); atria and ventricles beat independently. SYN: b. (3) , heart b.. bone b. surgical procedure in which a bone graft is placed adjacent to a joint to limit motion of the joint mechanically or to improve the stability of the joint, e.g., at the ankle joint to correct foot-drop by preventing plantarflexion past 0°, but allowing dorsiflexion beyond 0°, e.g., at the glenohumeral joint to prevent posterior instability. bundle-branch b. intraventricular b. due to interruption of conduction in one of the two main branches of the bundle of His and manifested in the electrocardiogram by marked prolongation of the QRS complex; b. of each branch has distinctive QRS morphology. complete AV b. 1. See atrioventricular b.. 2. SYN: complete atrioventricular dissociation. See atrioventricular b.. conduction b. failure of impulse transmission at some point along a nerve, although conduction along the segments proximal and distal to it are unaffected; clinically, most often the result of an area of focal demyelination; when caused by focal trauma, called neurapraxia. congenital heart b. atrioventricular b. present in utero or at birth and usually of advanced or complete degree. depolarizing b. skeletal muscle paralysis associated with loss of polarity of the motor endplate, as occurs following administration of succinylcholine. divisional b. arrest of the impulse in one of the assumed two main divisions of the left branch of the bundle of His; i.e., in either the anterior (superior)_ division or the posterior (inferior) division. SYN: hemiblock. entrance b. SYN: protective b.. epidural b. an obstruction in the epidural space; used inaccurately to refer to epidural anesthesia. exit b. inability of an impulse to leave its point of origin, the mechanism for which is conceived as an encircling zone of refractory tissue denying passage to the emerging impulse. fascicular b. a condition based on the disputed concept that the left branch of the bundle of His provides two of three major fascicles of a system of conduction, of which the right bundle branch constitutes the third, for the transmission of the cardiac impulse from the atrium above to the ventricles below the AV node; b. may occur in any or all fascicles, all three together producing complete AV b.. SEE ALSO: hemiblock. field b. regional anesthesia produced by infiltration of local anesthetic solution into tissues surrounding an operative field. first degree AV b. atrioventricular b.. heart b. SYN: atrioventricular b.. incomplete atrioventricular b. SYN: partial heart b.. interatrial b. SYN: intraatrial b.. intraatrial b. impaired conduction through the atria, manifested by widened and often notched P waves in the electrocardiogram. SYN: interatrial b.. intraventricular b. (IVB) , IV b. delayed conduction within the ventricular conducting system or myocardium, including bundle-branch, periinfarction blocks, fascicular blocks, nonspecific IV b.and Wolff-Parkinson-White (preexcitation) syndrome. Mobitz b. second degree atrioventricular b. in which there is a ratio of two or more atrial deflections (P waves) to ventricular responses. Mobitz types of atrioventricular b. type I, the dropped beat of the Wenckebach phenomenon; type II, a dropped cardiac cycle that occurs without alteration in the conduction of the preceding intervals. nerve b. interruption of conduction of impulses in peripheral nerves or nerve trunks by injection of local anesthetic solution. nondepolarizing b. skeletal muscle paralysis unaccompanied by changes in polarity of the motor endplate, as occurs following administration of tubocurarine. partial heart b. impulses penetrate the atrioventricular junction in some relation to the ventricular rate. SYN: incomplete atrioventricular b.. periinfarction b. an electrocardiographic abnormality associated with a myocardial infarct and caused by delayed activation of the myocardium in the region of the infarct; characterized by an initial vector directed away from the infarcted region with the terminal vector directed toward it. phase I b. inhibition of nerve impulse transmission across the myoneural junction associated with depolarization of the motor endplate, as in the muscle paralysis produced by succinylcholine. phase II b. inhibition of nerve impulse transmission across the myoneural junction unaccompanied by depolarization of the motor endplate, as in the muscle paralysis produced by tubocurarine. protective b. an incompletely understood mechanism whereby a pacemaker is protected from being discharged by the impulse from another center; the mechanism, usually conceived as an encircling zone of unidirectionally refractory tissue permitting egress of impulses from the center but preventing access to the center, is seen in operation in ventricular parasystole where the parasystolic center is protected from discharge by the sinus pacemaker and so is able to maintain its intrinsic rhythm undisturbed. SYN: entrance b., protection. pupillary b. increased resistance to flow of aqueous humor through the pupil from the posterior chamber to the anterior chamber, leading to anterior bowing of the peripheral iris over the trabecular meshwork and to angle-closure glaucoma. retrograde b. impaired conduction backward from the ventricles or AV node into the atria. reverse pupillary b. increased resistance to flow of aqueous humor through the pupil from the anterior chamber to the posterior chamber, leading to posterior bowing of the peripheral iris against the zonules; a possible mechanism for pigmentary glaucoma. second degree AV b. atrioventricular b.. sinoatrial b., S-A b., sinus b. blockade of the impulse leaving the sinus node before it can activate atrial muscle. SYN: sinoauricular b.. sinoauricular b. SYN: sinoatrial b.. spinal b. an obstruction to the flow of cerebrospinal fluid in the spinal subarachnoid space; used inaccurately to refer to spinal anesthesia. stellate b. injection of local anesthetic solution in the vicinity of the stellate ganglion. suprahisian b. atrioventricular conduction delay occurring above, or cephalad to, the bundle of His. third degree AV b. SYN: complete atrioventricular dissociation. See atrioventricular b.. unidirectional b. b. that prevents passage of an impulse when it approaches from one direction but not from the other, as when b. in the AV node prevents anterograde conduction to the ventricles while retrograde conduction to the atria remains intact. Wenckebach b. a form of b. in any cardiac tissue (most often the atrioventricular junction) in which there is progressive lengthening of conduction (decremental conduction) until the beat is dropped. Wolff-Chaikoff b. blocking of the organic binding of iodine and its incorporation into hormone caused by large doses of iodine; usually a transient effect, but in large doses in susceptible individuals it can be prolonged and cause iodine myxedema. SYN: Wolff-Chaikoff effect.

blockade (blok′ad)
1. Intravenous injection of large amounts of colloidal dyes or other substances in order to block reticuloendothelial cells ( e.g., phagocytosis is temporarily prevented). 2. Receptor b., blocking the effect of a hormone at the cell surface. 3. Arrest of peripheral nerve conduction or transmission at autonomic synaptic junctions, autonomic receptor sites, or myoneural junctions by a drug. 4. The occupation of receptors by an antagonist so that usual agonists are relatively ineffective. adrenergic b. selective inhibition by a drug of the responses of effector cells to adrenergic sympathetic nerve impulses (sympatholytic) and to epinephrine and related amines (adrenolytic). cholinergic b. 1. inhibition by a drug of nerve impulse transmission at autonomic ganglionic synapses (ganglionic b.), at postganglionic parasympathetic effector cells ( e.g., by atropine), and at myoneural junctions (myoneural b.); 2. the inhibition of a cholinergic agent. ganglionic b. inhibition of nerve impulse transmission at autonomic ganglionic synapses by drugs such as nicotine or hexamethonium. myoneural b. inhibition of nerve impulse transmission at myoneural junctions by a drug such as curare. narcotic b. the use of drugs to inhibit the effects of narcotic substances, as with naloxone. sympathetic b. interruption of transmission in sympathetic ganglia or conduction of impulses in pre- or postganglionic sympathetic nerve fibers. virus b. the interference of one virus by another, either attenuated or unrelated.

blocker (blok′er)
1. An instrument used to obstruct a passage. 2. See blocking agent. angiotensin receptor blockers agents, such as losartan, that bind with angiotensin receptors, thus preventing access of angiotensin II to the receptor and consequently reducing the vasoconstriction produced by this agonist; used in the treatment of hypertension. calcium channel b. a class of drugs with the capacity to prevent calcium ions from passing through biologic membranes. These agents are used to treat hypertension, angina pectoris, and cardiac arrhythmias; examples include nifedipine, diltiazem, verapamil, amlodipene.

blocking (blok′ing)
1. Obstructing; arresting of passage, conduction, or transmission. 2. In psychoanalysis, a sudden break in free association occurring when a painful subject or repressed complex is touched. 3. Sudden cessation of thoughts and speech, which may indicate the presence of a severe thought disorder or a psychosis. alpha b. the attenuation of the occipital alpha rhythm (8–14 Hz brain waves as seen on an electroencephalogram), produced by opening the eyes or by intense mental concentration.

block-out (blok′owt)
Elimination of undercuts by filling such areas with a medium such as wax or wet pumice.

Paul O., French physician, 1860–1896. See B. disease.

Eric D., 20th century U.S. speech-language pathologist. See B.-Singer valve.

blood (blud)
The “circulating tissue” of the body; the fluid and its suspended formed elements that are circulated through the heart, arteries, capillaries, and veins; b. is the means by which 1) oxygen and nutritive materials are transported to the tissues, and 2) carbon dioxide and various metabolic products are removed for excretion. The b. consists of a pale yellow or gray-yellow fluid, plasma, in which are suspended red b. cells (erythrocytes), white b. cells (leukocytes), and platelets. SEE ALSO: arterial b., venous b.. [A.S. blod] arterial b. b. that is oxygenated in the lungs, found in the left chambers of the heart and in the arteries, and relatively bright red. cord b. b. present in the umbilical vessels at the time of delivery. It is of fetal origin. laky b. b. that is undergoing or has undergone laking. See lake (2) , laky. occult b. b. in the feces in amounts too small to be seen but detectable by chemical tests. sludged b. b. in which the corpuscles, as a result of some general abnormal state, e.g., burns, traumatic shock, and similar stresses, become massed together in the capillaries, and thereby block the vessels or move slowly through them. venous b. b. which has passed through the capillaries of various tissues, except the lungs, and is found in the veins, the right chambers of the heart, and the pulmonary arteries; it is usually dark red as a result of a lower content of oxygen. whole b. b. drawn from a selected donor under rigid aseptic precautions; contains citrate ion or heparin as an anticoagulant; used as a b. replenisher.

blood bank
A place, usually a separate part or division of a hospital laboratory or a separtate free-standing facility, in which blood is collected from donors, typed, separated into several components, stored, and/or prepared for transfusion to recipients.

blood count
Calculation of the number of red (RBC) or white (WBC) blood cells in a cubic millimeter of blood, by means of counting the cells in an accurate volume of diluted blood. complete b. (CBC) a combination of the following determinations: red blood cell count, white blood cell count, erythrocyte indices, hematocrit, differential b., and sometimes platelet count. differential white b. an estimate of the percentage of each white blood cell type making up the total white blood cell count. Schilling b. a method of counting blood in which the polymorphonuclear neutrophils are separated into four groups according to the number and arrangement of the nuclear masses in these cells. SYN: Schilling index.

blood dust
SYN: hemoconia.

blood group
1. A system of antigens under the control of closely linked allelic loci on the surface of the erythrocyte. Because of the antigenic differences existing between individuals, blood groups are significant in blood transfusions, maternal-fetal incompatibilities (hemolytic disease of the newborn), tissue and organ transplantation, disputed paternity cases, and in genetic and anthropologic studies; certain blood groups may be related to susceptibility or resistance to certain diseases. Often used as synonymous with blood type. See Blood Groups appendix for individual groups: ABO, Auberger, Diego, Duffy, I, Kell, Kidd, Lewis, Lutheran, MNSs, P, Rh, Sutter, Xg, and the low-frequency and high-frequency blood groups. 2. The classification of blood samples by means of laboratory tests of their agglutination reactions with respect to one or more blood groups. In general, a suspension of erythrocytes to be tested is exposed to a known specific antiserum; agglutination of the erythrocytes indicates that they possess the antigen for which the antiserum is specific. Certain antisera require special testing conditions. private b. a b. that is known to have occurred in only one family and is traceable to one single person.

bloodless (blud′les)
Without blood.

bloodletting (blud′let-ing)
Removing blood, usually from a vein; formerly used as a general remedial measure, but used now in congestive heart failure and polycythemia. See phlebotomy. general b. removing blood by arteriotomy or phlebotomy. local b. removing blood from the smaller vessels, formerly by a cupping glass or by leeching.

blood relative
A popular term describing a relative of a person sharing a common ancestor. No special importance attaches to the blood as a vehicle of inheritance. Spouses are not ordinarily blood relatives and when they are, the marriage is consanguineous and carries a higher risk than average of progeny homozygous by descent from ancestors in common. Such marriages are discouraged and within certain degrees of kindred may be illegal.

bloodshot (blud′shot)
Denoting locally congested smaller blood vessels of a part ( e.g., the conjunctiva) which are dilated and visible.


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