Copy of `Dorland's Medical Dictionary`

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Dorland's Medical Dictionary
Category: Health and Medicine > Medical Dictionary
Date & country: He/al/th a, US
Words: 39623

(burth) a coming into being; the act or process of being born. multiple birth the birth of two or more offspring produced in the same gestation period. postterm birth birth of an infant at or after 42 completed weeks (294 days) of gestation. ...

birth canal
the canal through which the fetus passes in birth.

birth certificate
a written, authenticated record of the birth of a child, required in most countries of the world. After a birth is registered, the certificate is issued, representing legal proof of parentage, age, and citizenship. Birth certificates are of great personal and legal importance; they are required for many legal, business, a...

birth control
the concept of limiting the size of families by measures designed to prevent conception. This term has largely been superseded by the term family planning, which means planning the arrival of children to correspond with the desire and resources of the parent or parents. See also contraception.

birth palsy
birth paralysis obstetric paralysis.

birth rate
the number of live births in a geographic area in a defined period, usually one year, relative to some specified population. For the crude birth rate, it is the average total population or the midyear population in the area during the period. Specific birth rates for subsets of the population may also be calculated, for e...

birthing room
a hospital room that is utilized for labor and delivery. It is decorated in a homelike, comfortable fashion and contains a specially equipped bed that can be adjusted for delivery. Specialized equipment is often concealed.

(burth´mahrk) a congenital blemish or spot on the skin, usually visible at birth or shortly after; those appearing later are often at the location of a skin defect present at birth. See also nevus. vascular birthmark hemangioma.

bis in die
(bis in de´a) Latin phrase meaning twice a day; abbreviated b.i.d.

(bis-ak´ә-dәl) (bis″ә-ko´dәl) a contact laxative used before procedures involving the colon; administered orally or by rectal suppository, either as the base or as a complex with tannic acid (bisacodyl tannex).

(bis-ә-kro´me-әl) pertaining to the two acromial processes.

(bi-sek´shәn) division into two parts by cutting.

(bi-sek´shoo-әl) of or pertaining to bisexuality; see also ambisexual and unisexual. an individual exhibiting bisexuality.

(bi-sek″shoo-al´ĭ-te) true hermaphroditism; the condition of having gonads of both sexes. sexual attraction to persons of both sexes; exhibition of both homosexual and heterosexual behavior. existence of the psychological qualities of both sexes, both masculinity and femininity, in the s...

(bis-fe´re-әs) having two beats, as a bisferious pulse.

bisferious pulse
pulsus bisferiens.

Bishop score
(bish´әp) a score for estimating the prospects of induction of labor, arrived at by evaluating the extent of cervical dilatation, effacement, the station of the fetal head, consistency of the cervix, and the cervical position in relation to the vaginal axis.

(bis″hi-drok″se-koo´mә-rin) former name for dicumarol.

(bis-il´e-ak) pertaining to the two iliac bones or to any two corresponding points on them.

(Bi) (biz´mәth) a chemical element, atomic number 83, atomic weight 208.980. Its salts have been used for their antacid and mild astringent properties in relief of inflammatory diseases of the stomach and intestines, and as topical protectants in skin and anorectal disorders. ...

bismuth line
a thin blue-black line along the gingival margin in bismuth poisoning.

bismuth poisoning
poisoning from excessive or chronic ingestion of bismuth or its salts; symptoms include anuria, stomatitis, dermatitis, and diarrhea. Called also bismuthosis.

(biz″mә-tho´sis) chronic bismuth poisoning, with anuria, stomatitis, dermatitis, and diarrhea.

(bis″o-pro´lol) a synthetic beta-adrenergic blocking agent, used as the fumarate salt; administered orally as an antihypertensive agent.

(bis-fos´fә-nāt) diphosphonate.

(bis´tdbobr-re) a long, narrow surgical knife, straight or curved, used for incising abscesses and enlarging sinuses, fistulas, etc. Bistoury.

(bi-sul´fāt) an acid sulfate combining a sulfate radical with a monovalent metal and a hydrogen ion.

(bīt) seizure with the teeth. a wound or puncture made by a living organism. an impression made by closure of the teeth upon some plastic material, such as wax. occlusion (def. 2).

bite reflex
strong closure of the jaws when the teeth or gums are stimulated.

(bīt´wing) a wing or fin attached along the center of the tooth side of a dental x-ray film and bitten on by the patient, permitting production of a bite-wing radiograph.

(bi-tem´pә-rәl) pertaining to both temples or temporal bones.

(bīt´plāt) bite plate an appliance, usually plastic or wire, worn in the palate as a diagnostic or therapeutic adjunct in orthodontics or prosthodontics.

(bi´tis) a genus of poisonous, brightly colored, thick-bodied snakes with heart-shaped heads. It includes the puff adder (B. arie´tans), Gaboon viper (B. gabon´ica), and rhinoceros viper (B. nasicor´nis).

(bi-tol´tәr-ol) a beta-adrenergic receptor agonist used as a bronchodilator; administered by inhalation as the mesylate salt in the treatment of bronchospasm associated with asthma and the treatment and prophylaxis of bronchospasm associated with chronic obstructive airway disease, including bronchitis and pulmonary emp...

Bitot spots
foamy gray triangular spots of keratinized epithelium on the conjunctivae, a sign of vitamin A deficiency.

(bi″tro-kan-ter´ik) pertaining to both trochanters on one femur or to both greater trochanters.

bitter almond oil
the fixed oil expressed from the bitter almond; see also almond oil (def. 1). the volatile oil distilled from Prunus dulcis var. amara, or from other kernels containing amygdalin; it contains hydrogen cyanide and so has been replaced by benzaldehyde, which is not toxic, as a pharmaceutical flavoring agent.

bitter orange oil
a volatile oil obtained from the peel or flowers of the bitter orange, used as a flavoring agent.

(bi-too″mĭ-no´sis) a mild type of pneumoconiosis caused by inhaling dust from bituminous (soft) coal.

(bi´u-rәt) a urea derivative that forms a chelate having an intense violet-red color with copper sulfate in alkaline solution; this reaction is known as the biuret reaction. The same reaction also occurs when compounds having two or more adjacent peptide bonds (for example, proteins), are reacted with copper...

(bi-va´lәnt) divalent. the structure formed by a pair of homologous chromosomes joined by synapsis along their length during the zygotene and pachytene stages of the first meiotic prophase. After each homologous chromosome splits into two sister chromatids during the pachytene stage, this structure is call...

(bi-val´ĭ-roo-din) an inhibitor of the clot-promoting activity of thrombin, used in conjunction with aspirin as an anticoagulant in patients with unstable angina pectoris who are undergoing percutaneous transluminal coronary angioplasty; administered intravenously.

(bi-ven´trәl) having two bellies. digastric muscle.

(bi″ven-trik´u-lәr) pertaining to or affecting both ventricles of the heart.

biventricular pacing
that in which a lead is used to deliver current directly to the left ventricle, in addition to those used to deliver current to the right atrium and ventricle, so that the ventricles can be induced to pump in synchrony.

bizarre delusion
one that is patently absurd, with no possible basis in fact.

(bi″zi-go-mat´ik) pertaining to the two most prominent points of the two zygomatic arches.

Björnstad syndrome
(byorn´stahd) an autosomal recessive disorder characterized by congenital sensorineural deafness and pili torti.


BK virus
a virus of the genus Polyomavirus that is a common cause of infection in childhood and remains dormant in the person who has been infected. It is believed to cause hemorrhagic cystitis and nephritis in immunocompromised persons.

black cataract
black or dark-colored opacity occurring in senile nuclear sclerotic cataract.

Black Creek Canal virus
a virus of the genus Hantavirus that causes hantavirus pulmonary syndrome, found in warm regions of the Americas; the vectors are rodents, especially cotton rats of genus Sigmodon.

black death
bubonic plague; see plague.

black fever
visceral leishmaniasis.

black induration
the hardening and pigmentation of the lung tissue seen in coal workers' pneumoconiosis.

black lung
coal workers' pneumoconiosis.

black substance
substantia nigra.

black tongue
black hairy tongue hairy tongue in which the hypertrophied filiform papillae are brown or black.

black widow spider antivenin
antivenin (Latrodectus mactans).

Blackfan-Diamond anemia
(blak´fan di´mәnd) Blackfan-Diamond syndrome congenital hypoplastic anemia.

(blak´hed) a plug of keratin and sebum within the dilated orifice of a hair follicle. The dark color is caused not by dirt but by the discoloring effect of air on the sebum in the clogged pore. Infection may cause it to develop into a pustule or boil. See also acne vulgaris. Called also open comedo.

(blak´out) temporary loss of vision and momentary unconsciousness due to diminished circulation to the brain and retina. Blackout refers specifically to a condition which sometimes occurs in aviators resulting from increased acceleration, which causes a decrease in blood supply to the brain cells. The term can als...

blackwater fever
a severe complication of malaria characterized by intravascular hemolysis, hemoglobinuria, renal failure, and passage of dark brown or red urine, seen in association with intermittent quinine therapy, with Plasmodium falciparum infection in the nonimmune, or with interrupted exposure in the partially immune.

(blad´әr) a membranous sac, such as one serving as a receptacle for secretion. Called also cyst and vesica. urinary bladder.

bladder calculus
vesical calculus.

bladder cancer
malignancy of the urinary bladder; this is the most common site of malignancy of the urinary system. It affects men more often than women, and it is seen more often in persons over age 50. Suspected contributing factors include exposure to industrial substances such as aniline dyes, and to the toxins in cigarette smoke. T...

bladder cells
swollen cells in the epidermis of the tips of the fingers and toes of the embryo. Called also Zander cells.

bladder compliance
ability of the urinary bladder to stretch in response to pressure without being disrupted, expressed in milliliters per centimeter of water calculated as change in volume divided by change in pressure. The normal bladder has a compliance of no more than 2 cm increase in water pressure per 100 mL of fluid.

bladder neck
a constricted portion of the urinary bladder where its inferolateral surfaces meet at the opening of the urethra.

bladder reflex
the reflex contracting and emptying of the urinary bladder in response to filling, the first step in the micturition reflex; it can be voluntarily inhibited by impulses from the brain in patients with normal neurological function.

Blainville ears
asymmetry of the two ears.

Blair-Brown operation
repair of a cleft lip by the use of a lateral flap one-half the length of the lip.

Blalock-Hanlon operation
a palliative operation for transposition of the great vessels, consisting of the creation of an interatrial septal defect.

Blalock-Taussig operation
(bla´lok taw´sig) Blalock-Taussig shunt anastomosis of the subclavian artery to the pulmonary artery to shunt some of the systemic circulation into the pulmonary circulation; performed as palliative treatment of congenital pulmonary stenosis.

(blanch) to become pale.

bland diet
one that is free from any irritating or stimulating foods.

blanking period
a period of time during and after a pacemaker stimulus when the unstimulated chamber is insensitive to avoid sensing the electronic event in the stimulated chamber.

Blaskovics operation
an operation for ptosis of the upper eyelid, consisting of excision of the levator muscle and the tarsus through a conjunctival approach.

(blast) an immature stage in cellular development before appearance of the definitive characteristics of the cell; used also as a word termination, as in ameloblast and trophoblast. blast cell. the wave of air pressure produced by the detonation of high-explosive bombs or shells or by other e...

blast cell
in one theory of development, the least differentiated, totipotential blood cell without commitment as to its particular series, from which all blood cells are derived, preceding a stem cell. Called also blast, hematoblast, hemoblast, and hemocytoblast.

blast cell leukemia
acute undifferentiated leukemia.

blast crisis
a sudden, severe change in the course of chronic granulocytic leukemia, characterized by an increased number of blasts (myeloblasts or lymphoblasts).

(blas-te´mә) in species with asexual reproduction, a group of cells that give rise to a new individual. in other species, including humans, a group of cells showing little or no differentiation that gives rise to an organ or part in either normal development or regeneration.

(blas´to-sēl) the fluid-filled central segmentation cavity of the mass of the blastula.

(blas´to-sist) the mammalian conceptus in the postmorula stage, consisting of an embryoblast (inner cell mass) and a thin trophoblast layer enclosing a blastocyst cavity.

(blas´to-sīt) an undifferentiated embryonic cell.

(blas´to-dәrm) collectively, the mass of cells produced by cleavage of a zygote, forming the hollow sphere of the blastula, or the cellular cap above a floor of segmented yolk in the discoblastula of telolecithal eggs.

blastodermic layer
germ layer.

(blas″to-jen´ә-sis) development of an individual from a blastema (that is, by asexual reproduction). transmission of inherited characters by the germ plasm. morphological transformation of small lymphocytes into large lymphocytes (lymphoblasts) that accompanies lymphocyte activation.

blastogenic factor
lymphocyte-transforming factor.

(blas-to´mә) pl. blastomas, blasto´mata A neoplasm composed of embryonic cells derived from the blastema of an organ or tissue. adj., blasto´matous., adj.

(blas´to-mēr) one of the cells produced by cleavage of a fertilized oocyte (zygote). Called also cleavage cell.

(blas″to-mi´sēz) a genus of pathogenic fungi growing as mycelial forms at room temperature and as yeastlike forms at body temperature; applied to the yeasts pathogenic for humans and other animals. B. dermati´tidis is the species that causes North American blastomycosis.

(blas″to-mi´sēt) any organism of the genus Blastomyces. any yeastlike organism.

(blas″to-mi-ko´sis) infection with any yeastlike organism. an infection usually acquired through the pulmonary route, caused by Blastomyces dermatitidis. There may be suppurating tumors in the skin (cutaneous b.) or lesions in the lungs, bones, subcutaneous tissues, liver, spleen, and kidneys (systemic b.)...

(blas´to-por) the opening of the archenteron to the exterior of the embryo at the gastrula stage.

(blas´to-spor) a spore formed by budding, as in yeast.

(blas´tu-lә) pl. blas´tulae the usually spherical structure produced by cleavage of a zygote, consisting of a single layer of cells (blastoderm) surrounding a fluid-filled cavity (blastocoele); it follows the morula stage.

(blas″tu-la´shәn) conversion of the morula to the blastula by development of a blastocoele.

(bleb) bulla (def. 1).