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

tract
(trakt) a longitudinal assemblage of tissues or organs, especially a number of anatomic structures arranged in series and serving a common function, such as the gastrointestinal or urinary tract; also used in reference to a bundle (or fasciculus) of nerve fibers having a common origin, function, and termination within t...

traction
(trak´shәn) the exertion of a pulling force, such as along the long axis of something. It may be applied to a fractured bone or dislocated joint to maintain proper position and facilitate healing, or, in obstetrics, along the axis of the pelvis to aid in delivery when the fetus is in a difficult position.

traction alopecia
traumatic alopecia due to continuous or prolonged traction on the hair, such as in certain hairstyles or in the habit of compulsively twisting one's own hair.

traction diverticulum
a localized distortion, angulation, or funnel-shaped bulging of the esophageal wall, due to adhesions resulting from an external lesion.

tractotomy
(trak-tot´ә-me) transection of a nerve tract in the central nervous system, usually for the relief of intractable pain.

tractus
(trak´tәs) pl. trac´tus Latin word meaning tract; a term used in anatomy.

traditional Chinese medicine
the diverse body of medical theory and practice that has evolved in China, comprising four branches: acupuncture and moxibustion, herbal medicine, qi gong, and tui na. Although traditional Chinese medicine encompasses a variety of theory and practice, all of its forms share certain underlying characteristics. The body and mind ...

tragacanth
(trag´ә-kanth) the dried gummy exudation from Astragalus gummifer or other species of Astragalus; used as a suspending agent for drugs.

Trager Approach
Trager therapy service mark for a bodywork technique whose purpose is to train patients to develop awareness of movement patterns that relieve pain and promote relaxation. It consists of two components: tablework, in which the practitioner, in a meditative state, uses touch and gentle passive movement to assist the person ...

tragicus muscle
muscle of tragus: a short, flattened vertical band on the lateral surface of the tragus, innervated by the auriculotemporal and posterior auricular nerves.

tragus
(tra´gәs) pl. tra´gi the cartilaginous projection anterior to the external opening of the ear. (in the pl.) hairs growing on the pinna of the external ear, especially on the cartilaginous projection anterior to the external opening. adj., tra´gal., adj.

train-of-four
(trān әv fōr) a test for measuring the level of neuromuscular blockade: four consecutive stimuli are delivered along the path of a nerve and the response of the muscle is measured. Four equal muscle contractions will result if there is no neuromuscular blockade, but if the patient has a blockade, there w...

trained reflex
conditioned response.

trait
(trāt) any genetically determined characteristic. See also entries under character, gene, and inheritance. sometimes more specifically, the condition prevailing in the heterozygous state of a recessive disorder, such as sickle cell trait. a distinctive behavior pattern.

tramadol
(tram´ә-dol″) an opioid analgesic used as the hydrochloride salt for treatment of pain following surgical procedures and oral surgery; administered orally.

trance
(trans) a state of altered consciousness characterized by heightened focal awareness and reduced peripheral awareness; a sleeplike state of reduced consciousness and activity.

trandolapril
(tran-do´lә-pril″) an angiotensin-converting enzyme inhibitor used in treatment of hypertension and post–myocardial infarction congestive heart failure or left ventricular dysfunction; administered orally.

tranexamic acid
(tran″әk-sam´ik) an agent that combats fibrinolysis by competitively inhibiting activation of plasminogen; used in prophylaxis and treatment of hemorrhage associated with excessive fibrinolysis, such as that following oral surgery in patients with hemophilia; administered orally or intravenously.

tranquilizer
(trang″kwĭ-līz´әr) a drug with a calming, soothing effect; currently it is usually used to mean an antianxiety agent (minor tranquilizer). major tranquilizer former term for antipsychotic agent. minor tranquilizer antianxiety agent.

trans
(tranz) in organic chemistry, having certain atoms or radicals on opposite sides of a nonrotatable parent structure. in genetics, denoting two or more loci, especially pseudoalleles, occurring on opposite chromosomes of a homologous pair. See also cis and cis-trans test.

trans
fats see trans-fatty acids.

trans–
fatty acids stereoisomers of the naturally occurring cis–fatty acids, created by the addition of hydrogen to unsaturated fatty acids during the manufacture of margarine and shortening. Like saturated fatty acids, they raise the levels low-density lipoproteins and cholesterol. Called also trans fats.

transabdominal
(trans″ab-dom´ĭ-nәl) across the abdominal wall or through the abdominal cavity.

transactional analysis
a theory of personality structure and a psychotherapeutic method by which the human personality is viewed as consisting of three ego states: the Parent, the Adult, and the Child, coherent systems of thought and feeling that have corresponding patterns of behavior. The word transactional in this term refers to the communication ...

transaminase
(trans-am´ĭ-nās) any of a group of enzymes that catalyze the reversible transfer of an amino group from a donor, usually an amino acid, to an acceptor, usually a 2-keto acid. Most use pyridoxal phosphate as a coenzyme.

transamination
(trans″am-ĭ-na´shәn) the reversible exchange of amino groups between different amino acids.

transantral
(trans-an´trәl) performed across or through an antrum.

transaortic
(trans″a-or´tik) performed through the aorta or aortic valve; said of surgical procedures.

transatrial
(trans-a´tre-әl) performed through the atrium; said of surgical procedures.

transaudient
(trans-aw´de-әnt) penetrable by sound waves.

transaxial
(trans-ak´se-әl) directed at right angles to the long axis of the body or a part.

transbasal
(trans-ba´sәl) through the base, as a surgical approach through the base of the skull.

transcalent
(trans-ka´lәnt) penetrable by heat rays.

transcallosal
(trans-kә-lo´sәl) performed across or through the corpus callosum.

transcalvarial
(trans″kal-var´e-әl) through or across the calvaria.

transcatheter
(trans-kath´ә-tәr) performed through the lumen of a catheter.

transcendental meditation
a technique for attaining a state of physical relaxation and psychological calm by the regular practice of a relaxation procedure that entails the repetition of a mantra.

transcervical
(trans-sur´vĭ-kәl) performed through the cervical opening of the uterus. across or through the neck of a structure.

transcervical fracture
one through the neck of the femur.

transcobalamin
(trans″ko-bal´ә-min) either of two plasma proteins, transcobalamin I and transcobalamin II, that bind and transport cobalamins, including vitamin B12. Deficiency of transcobalamin II results in failure of immunoglobulin production, megaloblastic anemia, granulocytopenia, thrombocytopenia, and intestinal villous at...

transcondylar fracture
fracture of the humerus in which the line of fracture is at the level of the condyles, traverses the fossae, and is in part within the capsule of the joint; called also diacondylar fracture.

transcortical
(trans-kor´tĭ-kәl) connecting two parts of the cerebral cortex.

transcortin
(trans-kor´tin) an α-globulin that binds and transports biologically active, unconjugated cortisol in plasma.

transcranial
(trans-kra´ne-әl) performed through the cranium.

transcript
(trans´kript) a strand of nucleic acid that has been synthesized using another nucleic acid strand as a template.

transcriptase
(trans-krip´tās) RNA polymerase; an enzyme that catalyzes the synthesis (polymerization) of RNA from ribonucleoside triphosphates, with DNA serving as a template.

transcription
(trans-krip´shәn) the transfer of information. the synthesis of RNA using a DNA template, catalyzed by an RNA polymerase; the base sequences of the RNA and the DNA template are complementary. reverse transcription the synthesis of a DNA molecule complementary to ...

transcriptome
(trans-krip´tōm) the complete set of messenger RNAtranscripts produced by a genome.

transcutaneous
(trans″ku-ta´ne-әs) transdermal.

transcutaneous oxygen monitoring
a method for obtaining data about oxygen levels through electrodes attached to the skin. This method is preferred for ill neonates who cannot tolerate frequent drawing of blood samples for blood gas analysis. The PO2 levels obtained by cutaneous monitoring correlate with those obtained from samples of arterial blood and spare the neo...

transcutaneous pacemaker
a temporary pacemaker in which large surface, high impedance electrodes are applied to the anterior and posterior chest walls to deliver high current stimuli of long duration for pacing of the ventricles.

transdermal
(trans-dur´mәl) entering through the dermis, or skin, as in administration of a drug applied to the skin in ointment or patch form. See also percutaneous. Called also transcutaneous.

transdermal analgesia
a method of pain control in which a patch with a rate-controlling membrane is applied to the skin; the medication is deposited in the upper layers of the skin where it is absorbed into the systemic circulation.

transdermal delivery system
any means by which a drug is applied to the surface of the skin for transdermal absorption, such as a transdermal patch.

transdermal patch
a type of transdermal delivery system by which a patch containing medication is placed on the skin so that the medication is gradually absorbed over time.

transducer
(trans-doo´sәr) a device that translates one physical quantity to another, such as pressure or temperature to an electrical signal. neuroendocrine transducer a neuron, such as in the neurohypophysis, that on stimulation secretes a hormone and thus translates neural information into ...

transducin
(trans-doo´sin) a of the retinal rods that interacts with activated rhodopsin as part of the process of triggering a nerve impulse in vision.

transduction
(trans-duk´shәn) the transfer of genetic information from one bacterium to another with the DNA being transferred carried by a bacteriophage.

transdural
(trans-doo´rәl) through or across the dura mater.

transection
(tran-sek´shәn) a cross section; division by cutting transversely.

transesophageal
(trans″ә-sof″ә-je´әl) through or across the esophagus.

transethmoidal
(trans-eth-moi´dәl) performed across or through the ethmoid bone.

transfection
(trans-fek´shәn) originally, the artificial infection of bacterial cells by uptake of viral nucleic acid, resulting in the production of mature virus particles. Now, it includes any means of artificial introduction of foreign DNA into cultured eukaryotic cells; stable integration of the DNA into the recipien...

transfemoral
(trans-fem´or-әl) across or through the femur. through the femoral artery.

transfemoral amputation
amputation of the lower leg between the knee and the hip. Called also above-knee (A-K) amputation.

transfer
(trans´fәr) the taking or moving of something from one place to another. the moving of a patient from one surface to another. Patients can be taught to transfer safely either independently or with minimal assistance if they can balance in a sitting position.

transfer factor
(TF) a factor occurring in sensitized lymphocytes, having the capacity to transfer delayed hypersensitivity to a normal (nonreactive) individual. It confers cell-mediated immunity and therefore has been found to be useful in treating conditions in which there is a disorder of immune response. In conjunction with antibio...

transfer host
one that is used until the appropriate definitive host is reached, but is not necessary to completion of the life cycle of the parasite.

transfer RNA
(tRNA) a type of RNA that brings about the transfer of specific amino acid molecules to growing polypeptide chains during the synthesis of proteins. Each of the 20 common amino acids found in protein molecules has a corresponding type of transfer RNA. Thus, a specific tRNA carries the appropriate amino acid to its appro...

transferase
(trans´fәr-ās) an enzyme that catalyzes the transfer, from one molecule to another, of a chemical group that does not exist in free state during the transfer.

transference
(trans-fer´әns) in psychiatry, the unconscious tendency of a patient to assign to others in the present environment feelings and attitudes associated with significant persons in one's earlier life; especially, the patient's transfer to the therapist of feelings and attitudes associated with a parent or simil...

transfix
(trans´fiks) to pierce through or impale.

transfixion
(trans-fik´shәn) a cutting through from within outward, as in amputation.

transformation
(trans″for-ma´shәn) change of form or structure; conversion from one form to another. in oncology, the change that a normal cell undergoes as it becomes malignant. bacterial transformation the exchange of genetic material between strains of bacteria by the transf...

transformation zone
the area of the uterine cervix between the original squamocolumnar junction and the active one as it moves in response to puberty, pregnancy, menopause, and hormonal changes.

transformer
(trans-for´mer) an induction apparatus for changing electrical energy at one voltage and current to electrical energy at another voltage and current, through the medium of magnetic energy, without mechanical motion. step-down transformer one for lowering the voltage of the original ...

transfrontal
(trans-frun´tәl) through the frontal bone.

transfusion
(trans-fu´zhәn) the introduction of whole blood or blood components directly into the bloodstream. Among the elements transfused are packed red blood cells, plasma, platelets, granulocytes, and cryoprecipitate. It is preferred to transfuse blood components rather than whole blood because in that way the utility of each ...

transfusion nephritis
nephropathy following transfusion from an incompatible donor as a result of the hemoglobin of the hemolyzed red blood cells being deposited in the renal tubules.

transfusion reaction
any symptoms due to agglutination or hemolysis of the recipient's red blood cells when blood for a transfusion has been incorrectly matched and is incompatible. See blood group.

transgene
(trans´jēn) a segment of recombinant DNA that has been transferred from one genome to another; the term is sometimes used specifically to denote one that has been integrated into the germline of the recipient and is transmissible to future generations. adj. transgen´ic, adj. .

transglutaminase
(trans″gloo-tam´in-ās) the activated form of protransglutaminase, which forms stabilizing covalent bonds within fibrin strands; called also factor XIIIa (the activated form of factor XIII).

transhepatic biliary catheter
see biliary catheter.

transient global amnesia
a temporary episode of short-term memory loss without other neurological impairment.

transient ischemic attack
(TIA) a sudden episode of temporary symptoms caused by a lessening of blood flow through the brain, usually lasting one or two days; it is sometimes related to impaired blood flow through the vertebral or basilar arteries. Symptoms can range from obvious loss of sensation or motor function to more subtle changes i...

transient leukemia of infancy
transient myeloproliferative disorder.

transiliac
(trans-il´e-ak) across the two ilia.

transillumination
(trans″ĭ-loo″mĭ-na´shәn) the passage of strong light through a body structure, to permit inspection by an observer on the opposite side; called also diaphanoscopy.

transition zone
transitional zone any anatomical region that marks the point at which the constituents of a structure change from one type to another, such as the anocutaneous line.

transitional and respiratory zone
terminal respiratory unit.

transitional cell carcinoma
a malignant tumor arising from a transitional type of stratified epithelium, usually affecting the urinary bladder.

transitional cells
cells in the process of changing from one type to another. in the sinoatrial and atrioventricular nodes, small, slow-conducting, heterogeneous cells interposed between the P cells and Purkinje cells; they are thought to link the impulses generated by the P cells with the rest of the myocardium.

transitional epithelium
a type characteristically found lining hollow organs that are subject to great mechanical change due to contraction and distention, such as the urinary bladder. It was formerly thought to represent a transition between stratified squamous and columnar epithelium.

translation
(trans-la´shәn) the synthesis of a polypeptide using messenger RNA as a template, a complex process involving ribosomes and transfer RNAs; every three bases along the messenger RNA (a codon) specifies one amino acid in the polypeptide chain.

translocation
(trans″lo-ka´shәn) movement of a substance from one place to another; used particularly for movement within a biological fluid or across a biological membrane. movement of the ribosome from one codon to the next along the messenger RNA (mRNA) in protein synthesis. the transfer of ...

translocation Down syndrome
Down syndrome in which the excess chromosomal material (the long arm of chromosome 21) is translocated to another acrocentric chromosome (in standard trisomy 21 there is an additional chromosome 21). A carrier of the translocation chromosome has 45 chromosomes including the translocation chromosome and may be at increased...

translucent
(trans-loo´sәnt) slightly penetrable by light rays.

transluminal
(trans-loo´mĭ-nәl) through or across a lumen, particularly of a blood vessel.

transmandibular
(trans″man-dib´u-lәr) through or across the mandible.

transmembrane
(trans-mem´brān) crossing a membrane.