|Medical Dictionary - Dictionary of Medicine and Human Biology|
The state of consisting of many interrelated parts. chemical c. the number of different sequences in DNA as defined by hybridization kinetics.
Obsolete term for semispinalis capitis (muscle). [L. an embracing, encircling] c. olivaris inferior [TA] SYN: inferior olivary complex. c. stimulans cordis [TA] SYN: conducting system of heart.
1. A measure of the distensibility of a chamber expressed as a change in volume per unit change in pressure. 2. The consistency and accuracy with which a patient follows the regimen prescribed by a physician or other health professional. Cf.:adherence (2) , maintenance. 3. A measure of the ease with which a structure or substance may be deformed. In medicine and physiology, usually a measure of the ease with which a hollow viscus ( e.g., lung, urinary bladder, gallbladder) may be distended, i.e., the volume change resulting from the application of a unit pressure differential between the inside and outside of the viscus; the reciprocal of elastance. [M.E. fr. O.Fr., fr. L. compleo, to fulfill] bladder c. change in volume of bladder for a given change in pressure; can be calculated from a cytometrogram's pressure volume curve. SYN: c. of bladder, detrusor c.. c. of bladder SYN: bladder c.. detrusor c. SYN: bladder c.. dynamic c. of lung the value obtained when lung c. is estimated during breathing by dividing the tidal volume by the difference in instantaneous transpulmonary pressures at the ends of the respiratory excursions, when flow in the airway is momentarily zero; this value deviates markedly from static c. in patients in whom resistances and compliances are not uniform throughout the lung ( i.e., uneven time constants). c. of heart the reciprocal of passive or diastolic stiffness of the ventricle of the heart, most commonly of the left ventricle; one may distinguish between c. of the muscle and c. of the supportive structures, although ordinarily both are considered together (chamber c.); a hypertrophied or scarred heart will manifest a stiff wall, i.e., decreased c.. specific c. 1. the c. of a structure divided by its initial volume; 2. more specifically for the lungs, the c. divided by the functional residual capacity. static c. the value obtained when c. is measured at true equilibrium, i.e., in the absence of any motion. thoracic c. that portion of total ventilatory c. ascribable to c. of the thoracic cage. ventilatory c. the sum of dynamic c. of the lung and thoracic c..
Made complex; denoting a disease upon which a morbid process or event has been superimposed, altering symptoms and modifying its course for the worse. [L. com-plico, pp. -atus, to fold together]
A morbid process or event occurring during a disease that is not an essential part of the disease, although it may result from it or from independent causes.
An element forming a part of the whole. [L. com-pono, pp. -positus, to place together] anterior c. of force a force operating to move teeth anteriorly. c. of complement (C) any one of the nine distinct protein units designated C1 through C9. See complement. SEE ALSO: complement pathways. c. of force 1. one of the factors from which a resultant force may be compounded or into which it may be resolved; 2. one of the vectors into which a force may be resolved. components of mastication the various jaw movements that are made during the act of mastication, as determined by the neuromuscular system, the temporomandibular articulations, the teeth, and the food being chewed; divided, for purposes of analysis or description, into opening, closing, left lateral, right lateral, and anteroposterior components. components of occlusion the various factors involved in occlusion, such as the temporomandibular joint, the associated neuromusculature, the teeth, and the denture-supporting structures. plasma thromboplastin c. (PTC) SYN: factor IX. secretory c. a polypeptide chain found in external secretions ( e.g., tears, saliva, colostrum) associated with the immunoglobulins IgA and IgM. It also may occur in free form. The secretory piece is derived by proteolytic cleavage of the immunoglobulin receptor on epithelial cells.
A colloquial term for resin materials used in restorative dentistry. [L. compositus, put together, fr. compono, to put together]
In chemistry, the kinds and numbers of atoms constituting a molecule. [L. compono, to arrange] base c. the proportions of the four bases (adenine, cytosine, guanine, and thymine or uracil) present in DNA or RNA; usually expressed as the percentage (mol %) of G plus C. modeling c. SYN: modeling plastic.
compos mentis (kom′pos men′tis)
Of sound mind; usually used in its opposite form, non c.. [L. possessed of one's mind; compos, having control, + mens (ment-), mind]
1. In chemistry, a substance formed by the covalent or electrostatic union of two or more elements, generally differing entirely in physical characteristics from any of its components. 2. In pharmacy, denoting a preparation containing several ingredients. For compounds not listed here, see the specific chemical or pharmaceutical names. [through O.Fr., fr. L. compono] acetone c. SYN: ketone body. acyclic c. an organic c. in which the chain does not form a ring. SYN: aliphatic c., open chain c.. addition c. 1. strictly, a complex of two or more complete molecules in which each preserves its fundamental structure and no covalent bonds are made or broken ( e.g., hydrates of salts, adducts); 2. loosely, association of acids with basic organic compounds ( e.g., amines with HCl); 3. more loosely, addition of two molecules without loss of any atom, but forming new covalent bonds ( e.g., CH2&dbond;CH2 + Br2 → BrCH2&cbond;CH2Br). alicyclic compounds cyclic c.. aliphatic c. SYN: acyclic c.. APC c. an analgesic tablet drug combination containing aspirin, phenacetin, and caffeine. Very widely used in the 1940s through 1960s; original constituents of popular over-the-counter pain remedies. Use currently much diminished due to concerns about potential renal injury due to the phenacetin. aromatic c. cyclic c.. carbamino c. any carbamic acid derivative formed by the combination of carbon dioxide with a free amino group to form an N-carboxy group, &cbond;NH&cbond;COOH, as in hemoglobin forming carbaminohemoglobin. closed chain c. SYN: cyclic c.. condensation c. a c. resulting from the combination of two or more simple substances, with the splitting off of some other substance, such as alcohol or water; e.g., a peptide. Cf.:conjugated c.. conjugated c. a c. formed by the union of two compounds (as by the elimination of water between an alcohol and an organic acid to form an ester) and easily converted to the original compounds (hydrolysis). SEE ALSO: conjugation (4) . Cf.:condensation c.. cyclic c. any c. in which the constituent atoms, or any part of them, form a ring. Used mainly in organic chemistry where: 1) numerous compounds contain rings of carbon atoms (carbocyclic compounds) or carbon atoms plus one or more atoms of other types (heterocyclic compounds), usually nitrogen, oxygen, or sulfur; 2) where the atoms in the ring are all of the same element (homocyclic or isocyclic c.); 3) where the ring is saturated or contains nonconjugated double bonds (alicyclic c.), the c. is similar in properties to the corresponding acyclic c. ( e.g., cyclohexane resembles hexane); 4) where the ring contains conjugated double bonds in a closed loop in which there are 4n + 2 (where n is an integer) delocalized π electrons (Hückel rule) (aromatic c.; e.g., benzene, pyridine), it is more stable than the corresponding saturated ring and exhibits unusual chemical properties characteristic of itself and not of other types of rings or of acyclic compounds. These aromatic compounds have the ability to sustain an induced ring current. SYN: closed chain c., ring c.. genetic c. SYN: c. heterozygote. glycosyl c. the c. formed between a sugar and another organic substance in which the OH of the reducing (hemiacetal) group of the former is removed; e.g., the natural nucleosides, in which a heterocyclic N becomes linked directly to the C-1 of ribose (or deoxyribose) to yield ribosyl compounds. Cf.:glycoside. heterocyclic c. cyclic c.. high-energy compounds classically, a group of phosphoric esters whose hydrolysis takes place with a standard free energy change of −5 to −15 kcal/mol (or −20 to −63 kJ/mol) (in contrast to −1 to −4 kcal/mol, or −4 to −17 kJ/mol) for simple phosphoric esters like glucose 6-phosphate or α-glycerophosphates, thus being capable of driving energy-consuming reactions in living cells or reconstituted cell-free systems; adenosine 5′-triphosphate, with respect to the β- and γ-phosphates, is the best known and is regarded as the immediate energy source for most metabolic syntheses. Other examples include acid anhydrides, phosphoric esters of enols, phosphamic acid (R&cbond;NH&cbond;PO3H2) derivatives, acyl thioesters ( e.g., of coenzyme A), sulfonium compounds (R3&cbond;S+), and aminoacyl esters of ribosyl moieties. SEE ALSO: high-energy phosphates, under phosphate. homocyclic c. cyclic c.. impression c. SYN: modeling plastic. inclusion c. the mechanical trapping of small molecules within spaces between other molecules; e.g., the inclusion of iodine molecules by starch molecules to form the well-known red-to-black “addition c.” inorganic c. a c. in which the atoms or radicals consist of elements other than carbon and are typically held together by electrostatic forces rather than by covalent bonds; often are capable of dissociation into ions in polar solvents ( e.g., H2O). Cf.:organic c.. isocyclic c. cyclic c.. Kendall compounds a group of corticosteroids. Kendall's c. A (11-dehydrocorticosterone, Kendall c. B (corticosterone), Kendall c. E (cortisone), Kendall c. F (cortisol). SYN: Kendall substance. meso compounds compounds containing more than one asymmetric carbon atom, with configurations about them so balanced that the molecule as a whole possesses a plane of symmetry, although the individual carbon atoms do not; such compounds are not optically active; e.g., ribitol, mucic acid, meso-inositol, meso-cystine. methonium compounds agents that either block impulses in ganglia ( e.g., hexamethonium) and are used in arterial hypertension or block at neuromuscular junctions and are used for neuromusclar paralysis in surgery ( e.g., decamethonium). modeling c. SYN: modeling plastic. nonpolar c. a c. composed of molecules that possess a symmetrical distribution of charge, so that no positive or negative poles exist, and that are not ionizable in solution; e.g., hydrocarbons. SEE ALSO: organic c.. open chain c. SYN: acyclic c.. organic c. a c. composed of atoms (some of which are carbon) held together by covalent (shared electron) bonds. Cf.:inorganic c.. polar c. a c. in which the electric charge is not symmetrically distributed, so that there is a separation of charge or partial charge and formation of definite positive and negative poles; e.g., H2O. See also inorganic c.. Reichstein c. SYN: Reichstein substance. ring c. SYN: cyclic c.. Wintersteiner c. F SYN: cortisone.
Knowledge or understanding of an object, situation, event, or verbal statement.
A pad of gauze or other material applied for local pressure. [L. com-primo, pp. -pressus, to press together] graduated c. layers of cloth thickest in the center, becoming thinner toward the periphery. wet c. gauze moistened with saline or antiseptic solution.
A squeezing together; the exertion of pressure on a body in such a way as to tend to increase its density; the decrease in a dimension of a body under the action of two external forces directed toward one another in the same straight line. c. of brain SYN: cerebral c.. cerebral c. pressure upon the intracranial tissues by an effusion of blood or cerebrospinal fluid, an abscess, a neoplasm, a depressed fracture of the skull, or an edema of the brain. SYN: c. of brain. c. limiting a hearing aid circuit in which amplification is reduced at high input levels. c. of tissue SYN: tissue displaceability. wide dynamic range c. a hearing aid circuit in which amplification is increased across the frequency range at low input levels.
compressor (kom-pres′er, -or)
1. A muscle, contraction of which causes compression of any structure. 2. An instrument for making pressure on a part, especially on an artery to prevent loss of blood. SYN: compressorium. c. urethrae [TA] part of female external urethral sphincter arising from the ischiopubic rami, posterior to the plane of the urethra, passing anteriorly and medially to fuse with the contralateral muscle anterior to the urethra and blending with the other parts of the external urethral sphincter (sphincter urethrovaginalis inferiorly and sphincter urethrae superiorly). SEE ALSO: external urethral sphincter. c. venae dorsalis penis a variation of the bulbospongiosus muscle in which some fibers pass dorsal to the dorsal vein of the penis; thought at one time to be an important component in the mechanism of erection. SYN: Houston muscle.
SYN: compressor (2) .
Arthur H., U.S. physicist and Nobel laureate, 1892–1962. See C. effect, C. scattering.
SYN: Compton effect.
Uncontrollable thoughts or impulses to perform an act, often repetitively, as an unconscious mechanism to avoid unacceptable ideas and desires which, by themselves, arouse anxiety; the anxiety becomes fully manifest if performance of the compulsive act is prevented; may be associated with obsessive thoughts. [L. com-pello pp. -pulsus, to drive together, compel]
Influenced by compulsion; of a compelling and irresistible nature.
A programmable electronic device that can be used to store and manipulate data in order to carry out designated functions; the two fundamental components are hardware, i.e., the actual electronic device, and software, i.e., the instructions or program used to carry out the function.
With, together, in association; appears as com- before p, b, or m, as col- before l, and as co- before a vowel; corresponds to G. syn-. [L. cum, with, together]
conA, con A
Abbreviation for concanavalin A.
A glycoprotein containing d-mannose and d-galactose, constituting about 12% of total solids of egg white. It will bind iron ions. SYN: ovotransferrin.
A steroid alkaloid; pregnane with a methylimino group bridging C-18 and C-20 (in α-configuration). SEE ALSO: conessine.
SYN: pineal body. [G. konarion (dim. of konos, cone), the pineal body]
The conscious tendency to act, usually an aspect of mental process; historically aligned with cognition and affection, but more recently used in the wider sense of impulse, desire, purposeful striving. [L. conatio, an undertaking, effort]
Pertaining to, or characterized by, conation.
conatus (ko-nah′tus, -na′tus)
A striving toward self-preservation and self-affirmation. [L. attempt]
A system of interconnecting cavities. [L. concameratio, a vault; fr. concamero, pp. -atus, to vault over, fr. camera, a vault]
concanavalin A (conA, con A) (kon-ka-nav′a-lin)
A phytomitogen, extracted from the jack bean (Canavalia ensiformis) that agglutinates the blood of mammals and reacts with glucosans; like other phytohemagglutinins, conA stimulates T lymphocytes more vigorously than it does B lymphocytes.
A linear repeat of restriction fragments. [concatenate + -mer]
Denoting the arrangement of a number of structures, e.g., enlarged lymph glands, in a row like the links of a chain. [L. concateno, pp. -atus, to link together, fr. catena, a chain]
Luigi M., Italian physician, 1825–1882. See C. disease.
Having a depressed or hollowed surface. [L. concavus, arched or vaulted]
A hollow or depression, with more or less evenly curved sides, on any surface.
Concave on one surface and convex on the opposite surface.
concentration (c) (kon-sen-tra′shun)
1. A preparation made by extracting a crude drug, precipitating from the solution, and drying. 2. Increasing the amount of solute in a given volume of solution by evaporation of the solvent. 3. The quantity of a substance per unit volume or weight. In renal physiology, symbol U for urinary c., P for plasma c.; in respiratory physiology, symbol C for amount per unit volume in blood, F for fractional c. (mole fraction or volume per volume) in dried gas; subscripts indicate location and chemical species. [L. con-, together, + centrum, center] Baermann c. preparation that relies on the principle that active nematode larvae will migrate from a fresh fecal specimen through several layers of gauze into tap water, from which the larvae can be recovered by centrifugation. buffy coat c. centrifugation of whole blood containing anticoagulant to obtain a buffy coat layer containing white blood cells; blood films for staining can be prepared from this layer of cells and examined for the presence of parasites (trypanosomes and intracellular leishmaniae). critical micelle c. (cmc) the c. at which an amphipathic molecule ( E.G., a phospholipid) will form a micelle. fecal c. preparation using centrifugation and either flotation or sedimentation methods to separate parasitic elements from fecal debris. formalin-ether sedimentation c. a sedimentation method to separate parasitic elements from fecal debris through centrifugation and the use of ether to trap debris in a separate layer from the parasites. formalin-ethyl acetate sedimentation c. a sedimentation method to separate parasitic elements from fecal debris through centrifugation and the use of ethyl acetate (substitute for ether) to trap debris in a separate layer from the parasites. gravity c. a method of separating parasites from debris through gravity sedimentation of fecal suspensions. M c. the maximum number of bacterial cells which can be produced in a unit volume of growth medium. mean corpuscular hemoglobin c. (MCHC) Hgb/Hct;the average hemoglobin c. in a given volume of packed red cells, calculated from the hemoglobin therein and the hematocrit, in erythrocyte indices. microhematocrit c. the centrifugation of whole, anticoagulated blood, using microhematocrit tubes, to obtain a buffy coat layer containing white blood cells; blood films for staining can be prepared from this layer of cells and examined for the presence of parasites (trypanosomes and intracellular leishmaniae). minimal alveolar c. the end-alveolar c. of an inhalation anesthetic that prevents somatic response to a painful stimulus in 50% of individuals; an index of relative potency of inhalation anesthetics. SYN: minimal anesthetic c.. minimal anesthetic c. (MAC) SYN: minimal alveolar c.. minimal inhibitory c. (MIC) the lowest c. of antibiotic sufficient to inhibit bacterial growth when tested in vitro. molar c. molar (4) . normal c. (n) normal (3) . zinc sulfate flotation c. a method using saturated zinc sulfate to separate parasitic elements from fecal debris through differences in specific gravity; most parasite cysts, oocysts, spores, eggs, and larvae can be found in the surface film after centrifugation.
Having a common center, such that two or more spheres, circles, or segments of circles are within one another.
1. An abstract idea or notion. 2. An explanatory variable or principle in a scientific system. SYN: conception (1) . [L. conceptum, something understood, pp. ntr. of concipio, to receive, apprehend] no-threshold c. that the biologic effect of radiation is proportional to dose, even for minutely small doses. self-c. an individual's sense of self, including self-definition in the various social roles one enacts, including assessment of one's own status with respect to a single trait or to many human dimensions, using societal or personal norms as criteria.
Plural of conceptus.
1. SYN: concept. 2. Act of forming a general idea or notion. 3. Act of conceiving; the implantation of the blastocyte in the endometrium. [L. conceptio; see concept] imperative c. a concept that does not arise from association but appears spontaneously and refuses to be banished. retained products of c. fragments of fetal, placental, or membrane tissue remaining in utero following delivery or abortion, posing an increased risk of bleeding or infection.
Relating to the formation of ideas, usually higher order abstractions, to mental conceptions.
conceptus, pl .concepti (kon-sep′tus, -sep′ti)
The product of conception, i.e., embryo or fetus and membranes.
concha, pl .conchae (kon′ka, kon′ke) [tA]
In anatomy, a structure comparable to a shell in shape, as the auricle or pinna of the ear or a turbinate bone in the nose. [L. a shell] c. of auricle [TA] the large hollow, or floor of the auricle, between the anterior portion of the helix and the antihelix; it is divided by the crus of the helix into the cymba above and the cavum below. SYN: c. auriculae [TA] , c. of ear. c. auriculae [TA] SYN: c. of auricle. c. bullosa abnormal pneumatization of the middle turbinate that may interfere with normal ventilation of sinus ostia and can result in recurrent sinusitis. c. of ear SYN: c. of auricle. highest c. SYN: supreme nasal c.. inferior nasal c. [TA] 1. a thin, spongy, bony plate with curved margins, on the lateral wall of the nasal cavity, separating the middle from the inferior meatus; it articulates with the ethmoid, lacrimal, maxilla, and palate bones; 2. the above bony plate and its thick mucoperiosteum containing an extensive cavernous vascular bed for heat exchange. SYN: c. nasalis inferior [TA] , inferior turbinated bone, turbinated body (2) . middle nasal c. [TA] 1. the middle thin, spongy, bony plate with curved margins, part of the ethmoidal labyrinth, projecting from the lateral wall of the nasal cavity and separating the superior meatus from the middle meatus; 2. the above bony plate and its thick mucoperiosteum containing a cavernous vascular bed for heat exchange. SYN: c. nasalis media [TA] , middle turbinated bone, turbinated body (2) . Morgagni c. SYN: superior nasal c.. c. nasalis inferior [TA] SYN: inferior nasal c.. c. nasalis media [TA] SYN: middle nasal c.. c. nasalis superior [TA] SYN: superior nasal c.. c. nasalis suprema [TA] SYN: supreme nasal c.. Santorini c., c. santorini SYN: supreme nasal c.. sphenoidal conchae [TA] pyramidal paired ossicles, the spines of which are in contact with the medial pterygoid lamina, the bases forming the roof of the nasal cavity. SYN: conchae sphenoidales [TA] , Bertin bones, Bertin ossicles, sphenoidal turbinated bones. conchae sphenoidales [TA] SYN: sphenoidal conchae. superior nasal c. [TA] 1. the upper thin, spongy, bony plate with curved margins, part of the ethmoidal labyrinth, projecting from the lateral wall of the nasal cavity and separating the superior meatus from the sphenoethmoidal recess; 2. the above bony plate and its thick mucoperiosteum, which is less vascular than that of the middle and inferior conchae. SYN: c. nasalis superior [TA] , Morgagni c., superior turbinated bone, turbinated body (2) . supreme c. SYN: supreme nasal c.. supreme nasal c. [TA] a small c. frequently present on the posterosuperior part of the lateral nasal wall; it overlies the supreme nasal meatus. SYN: c. nasalis suprema [TA] , fourth turbinated bone, highest c., highest turbinated bone, Santorini c., c. santorini, supraturbinal, supreme c., supreme turbinated bone, turbinated body (2) .
Shaped like a shell; having alternate convexities and concavities on the surface. [concha + G. eidos, appearance]
In esotropia, one eye accompanying the other in all excursions, as in concomitant strabismus. [con- + L. comito-, pp. -atus, to accompany]
1. Agreement in the types of data that occur in natural pairs. For example, in a trait like schizophrenia, a pair of identical twins is concordant if both are affected or both are unaffected; it is discordant if one of them only is affected. Likewise, the pairs might be non-identical twins, or sibs, or husband and wife, etc. 2. A negotiated, shared agreement between clinician and patient concerning treatment regimen(s), outcomes, and behaviors; a more cooperative relationship than those based on issues of compliance and noncompliance. [L. concordia, agreeing, harmony]
Denoting or exhibiting concordance.
A concretion; a deposit of calcareous material in a part. [L. con- cresco, to grow together]
1. SYN: coalescence. 2. In dentistry, the union of the roots of two adjacent teeth by cementum. [see concrement]
concretio cordis (kon-kre′she-o kor′dis)
Extensive adhesion between parietal and visceral layers of the pericardium with partial or complete obliteration of the pericardial cavity. SYN: internal adhesive pericarditis.
The formation of solid material by aggregation of discrete units or particles. [L. cum, together, + crescere, to grow]
Inability to abstract with an overemphasis on specific details; seen in mental disorders, such as dementia and schizophrenia, and also normally in children. [L. con-cresco, pp. -cretus, to grow together, harden]
1. A violent shaking or jarring. 2. An injury of a soft structure, as the brain, resulting from a blow or violent shaking. SYN: commotio. [L. concussio, fr. con- cutio, pp. -cussus, to shake violently] brain c. a clinical syndrome due to mechanical, usually traumatic, forces; characterized by immediate and transient impairment of neural function, such as alteration of consciousness, disturbance of vision and equilibrium, etc. SYN: commotio cerebri. spinal c. SYN: spinal cord c.. spinal cord c. injury to the spinal cord due to a blow to the vertebral column with transient or prolonged dysfunction below the level of the lesion. SYN: spinal c..
1. Making more solid or dense. 2. The change of a gas to a liquid, or of a liquid to a solid. 3. In psychoanalysis, an unconscious mental process in which one symbol stands for a number of others. 4. In dentistry, the process of packing a filling material into a cavity, using such force and direction that no voids result. [L. con-denso, pp. -atus, to make thick, condense] aldol c. formation of an aldol (a β-hydroxy carbonyl compound) from two carbonyl compounds; the reverse reaction is an aldol cleavage; fructose 1,6-bisphosphate aldolase catalyzes such a reaction. Claisen c. the formation of a β-keto ester from two esters, one of which has an α-hydrogen atom; malate synthase, citrate synthase, and ATP citrate lyase all catalyze such reactions.
To pack; to increase the density of; applied particularly to insertion of gold foil or silver amalgam in a cavity prepared in a tooth.
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