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Medical Dictionary


specialization (spesh′a-li-za′shun)
1. Professional attention limited to a particular specialty or subject area for study, research, and/or treatment. 2. SYN: differentiation (1) .

specialize (spesh′a-liz)
To engage in specialization (1).

specialty (spesh′al-te)
The particular subject area or branch of medical science to which one devotes professional attention. [L. specialitas fr. specialis, special]

speciation (spe-she-a′shun)
The evolutionary process by which diverse species of animals or plants are formed from a common ancestral stock.

species, pl .species (spe′shez)
1. A biologic division between the genus and a variety or the individual; a group of organisms that generally bear a close resemblance to one another in the more essential features of their organization, and breed effectively producing fertile progeny. 2. A class of pharmaceutical preparations consisting of a mixture of dried plants, not pulverized, but in sufficiently fine division to be conveniently used in the making of extemporaneous decoctions or infusions, as a tea. [L. appearance, form, kind, fr. specio, to look at] type s. the name of the single s. or of one of the s. of a genus or subgenus when the name of the genus or subgenus was originally validly published.

Characteristic of a given species; serum that is produced by the injection of immunogens into an animal, and that acts only upon the cells, protein, etc., of a member of the same species as that from which the original antigen was obtained.

specific (spe-sif′ik)
1. Relating to a species. SEE ALSO: s. epithet. 2. Relating to an individual infectious disease, one caused by a special microorganism. 3. A remedy having a definite therapeutic action in relation to a particular disease or symptom, as quinine in relation to malaria. [L. specificus fr. species + facio, to make]

specificity (spes-i-fis′i-te)
1. The condition or state of being specific, of having a fixed relation to a single cause or to a definite result; manifested in the relation of a disease to its pathogenic microorganism, of a reaction to a certain chemical union, or of an antibody to its antigen or the reverse. 2. In clinical pathology and medical screening, the proportion of individuals with negative test results for the disease that the test is intended to reveal, i.e., true negative results as a proportion of the total of true negative and false-positive results. Cf.:sensitivity (2) . analytical s. freedom from interference by any element or compound other than the analyte. diagnostic s. the probability (P) that, given the absence of disease (D), a normal test result (T) excludes disease; i.e., P(T/D). relative s. the s. of a medical screening test as determined by comparison with the same type of test ( e.g., s. of a new serological test relative to s. of an established serological test). substrate s. the ability of an enzyme to recognize and bind its substrates, typically measured by the Vmax/Km or kcat/Km ratios.

specillum, pl .specilla (spe-sil′um, -la)
A probe or small sound. [L. a probe, fr. specio, to look at]

specimen (spes′i-men)
A small part, or sample, of any substance or material obtained for testing. [L. fr. specio, to look at] cytologic s. a s. obtainable by a variety of methods from many areas of the body, including the female genital tract, respiratory tract, urinary tract, alimentary tract, and body cavities; used for cytologic examination and diagnosis ( e.g., cytologic smears, filter preparations, centrifuged buttons).

Abbreviation for single photon emission computed tomography.

spectacles (spek′ti-klz)
Lenses set in a frame that holds them in front of the eyes, used to correct errors of refraction or to protect the eyes. The parts of the s. are the lenses; the bridge between the lenses, resting on the nose; the rims or frames, encircling the lenses; the sides or temples that pass on either side of the head to the ears; the bows, the curved extremities of the temples; the shoulders, short bars attached to the rims or the lenses and jointed with the sides. SYN: eyeglasses, glasses (1) . [L. specto, pp. -atus, to watch, observe] bifocal s. s. with bifocal lenses. See lens. clerical s. SYN: half-glass s.. divers' s. strongly convex lenses for clear vision underwater. divided s. SYN: Franklin s.. Franklin s. an early form of bifocal s. in which the lower half of the lens is for near vision, the upper half for distant vision. SYN: divided s.. half-glass s. s., used for reading, in which the upper portion of the lenses are removed. SYN: clerical s., pantoscopic s., pulpit s.. hemianopic s. s. with a prism or mirror to allow the person with homonymous hemianopia to see objects in the blind half field. lid crutch s. s. with little offsets of metal with smooth edges which engage above the upper eyelid and keep it raised above the pupil in cases of paralytic blepharoptosis. SYN: Masselon s.. Masselon s. SYN: lid crutch s.. orthoscopic s. convex lenses with base-in prisms for close work. pantoscopic s. SYN: half-glass s.. photochromic s. s. with lenses that darken on exposure to ultraviolet light. protective s. s. which protect against ultraviolet or infrared rays or against mechanical injuries. SYN: safety s.. pulpit s. SYN: half-glass s.. safety s. SYN: protective s.. stenopeic s., stenopaic s. 1. opaque disks with narrow slits in the center allowing only a minimum amount of light to enter; used as a protection against snow blindness; 2. s. having opaque disks with multiple perforations used to aid vision in incipient cataract and in discrete opacities of the cornea; occasionally used as a substitute for corrective lenses or sunglasses. telescopic s. magnifying s. obtained by using a convex objective lens and a concave eyepiece separated by the difference in their focal lengths.

spectinomycin hydrochloride (spek′ti-no-mi′sin)
An antibiotic antibacterial agent.

spectra (spek′tra)
Plural of spectrum. [L.]

spectral (spek′tral)
Relating to a spectrum.

spectrin (spek′trin)
A filamentous contractile protein that together with actin and other cytoskeleton proteins forms a network that gives the red blood cell membrane its shape and flexibility; a defect or deficiency of s. is associated with hereditary spherocytosis and hereditary elliptocytosis; the principal component of the membrane skeleton of red cells. It comprises two units, an alpha unit of MW 240,000 [MIM*182860] and a beta unit of MW 225,000 [MIM*182870].

A spectrum. [L. spectrum, an image]

spectrochemistry (spek′tro-kem′is-tre)
The study of chemical substances and their identification by means of spectroscopy, i.e., by light emitted or absorbed.

spectrocolorimeter (spek′tro-kol-er-im′e-ter)
A colorimeter using a source of light from a selected portion of the spectrum, i.e., of a selected wavelength.

spectrofluorometer (spek-tro-flor-om′e-ter)
An instrument for measuring the intensity and quality of fluorescence.

spectrogram (spek′tro-gram)
A graphic representation of a spectrum. [spectro- + G. gramma, something written]

spectrograph (spek′tro-graf)
An instrument used in spectography. mass s. an instrument that subjects charged and accelerated ions (atomic or molecular) to a magnetic field that imparts a curved path that differs for each mass-to-charge ratio, thus separating individual species; used in detecting and assaying isotopic ratios and in molecular structure determinations.

spectrography (spek-trog′ra-fe)
The procedure of photographing or tracing a spectrum. [spectro- + G. grapho, to write]

spectrometer (spek-trom′e-ter)
An instrument for determining the wavelength or energy of light or other electromagnetic emission. [spectro- + G. metron, measure]

spectrometry (spek-trom′e-tre)
The procedure of observing and measuring the wavelengths of light or other electromagnetic emissions. clinical s. SYN: biospectrometry.

spectrophobia (spek-tro-fo′be-a)
Morbid fear of mirrors or of one's mirrored image. [spectro- + G. phobos, fear]

spectrophotofluorimetry (spek′tro-fo′to-flor-im′e- tre)
Measurement of the intensity and quality of fluorescence by means of a spectrophotometer.

spectrophotometer (spek′tro-fo-tom′e-ter)
An instrument for measuring the intensity of light of a definite wavelength transmitted by a substance or a solution, giving a quantitative measure of the amount of material in the solution absorbing the light; a colorimeter with a choice of wavelength and photometric measurement. [spectro- + photometer]

spectrophotometry (spek′tro-fo-tom′e-tre)
Analysis by means of a spectrophotometer. atomic absorption s. determination of concentration by the ability of atoms to absorb radiant energy of specific wavelengths. flame emission s. determination of the concentration of an element by measurement of light emitted when the element is excited by energy in the form of heat.

spectropolarimeter (spek′tro-po-lar-im′e-ter)
An instrument for measuring the rotation of the plane of polarized light of specific wavelength upon passage through a solution or translucent solid. [spectro- + polarimeter]

spectroscope (spek′tro-skop)
An instrument for resolving light from any luminous body into its spectrum, and for the analysis of the spectrum so formed. It consists of a prism that refracts the light or a grating for diffraction of the light, an arrangement for rendering the rays parallel, and a telescope that magnifies the spectrum. [spectro- + G. skopeo, to view] direct vision s. a s. consisting of a single tube containing a series of prisms; one end of the tube is placed in as close contact as possible with the substance to be examined while the observer's eye is at the opposite end; it can be used to make a spectroscopic examination of the blood in vivo, as in the ear lobe or web of the thumb.

spectroscopic (spek-tro-skop′ik)
Relating to or performed by means of a spectroscope.

spectroscopy (spek-tros′ko-pe)
Observation and study of spectra of absorbed or emitted light by means of a spectroscope. clinical s. SYN: biospectroscopy. infrared s. the study of the specific absorption in the infrared region of the electromagnetic spectrum; used in the study of the chemical bonds within molecules. magnetic resonance s. detection and measurement of the resonant spectra of molecular species in a tissue or sample.

spectrum, pl .spectraspectrums (spek′trum, -a, -umz)
1. The range of colors presented when white light is resolved into its constituent colors by being passed through a prism or through a diffraction grating: red, orange, yellow, green, blue, indigo, and violet, arranged in increasing frequency of vibration or decreasing wavelength. 2. Figuratively, the range of pathogenic microorganisms against which an antibiotic or other antibacterial agent is active. 3. The plot of intensity vs. wavelength of light emitted or absorbed by a substance, usually characteristic of the substance and used in qualitative and quantitative analysis. 4. The range of wavelengths presented when a beam of radiant energy is subjected to dispersion and focused. [L. an image, fr. specio, to look at] absorption s. the s. observed after light has passed through, and been partially absorbed by, a solution or translucent substance; many molecular groupings have characteristic light absorption patterns, which can be used for detection and quantitative assay. antimicrobial s. s. (2) . broad s. a term indicating a broad range of activity of an antibiotic against a wide variety of microorganisms. chromatic s. the continuum of colors that white light forms on passing through a prism or diffraction grating. SYN: color s.. color s. SYN: chromatic s.. continuous s. a s. in which there are no absorption bands or lines. excitation s. fluorescence produced over a range of wavelengths of the exciting light. fluorescence s. fluorescence evoked over a range of wavelengths when the excitation wavelength is at a maximum. fortification s. the zigzag banding of light, resembling the walls of fortified medieval towns, that marks the margin of the scintillating scotoma of migraine. SYN: fortification figures, telehopsias. frequency s. the range of frequencies in a signal, used to describe the resolving power of an imaging system in radiology. infrared s. the part of the invisible s. of wavelengths just longer than that of visible red light. SYN: thermal s.. invisible s. the radiation lying on either side of visible light, i.e., infrared and ultraviolet light. Raman s. the characteristic array of light produced by the Raman effect. thermal s. SYN: infrared s.. ultraviolet s. the electromagnetic s. at wavelengths shorter than the violet end of the visible s.. visible s. that part of electromagnetic radiation that is visible to the human eye; it extends from extreme red, 7606 Å (760.6 nm), to extreme violet, 3934 Å (393.4 nm). vocal s. the frequency and intensity ranges of the voice. wide s. s. (3) .

speculum, pl .specula (spek′u-lum, -la)
An instrument for exposing the opening of any canal or cavity in order to facilitate inspection of its interior. [L. a mirror, fr. specio, to look at] bivalve s. a s. with two adjustable blades. Cooke s. a three-pronged s. for rectal examinations and operations. duckbill s. a bivalve s., the blades of which are broad and flattened, resembling a duck's bill, used in inspection of the vagina and cervix. eye s. an instrument for keeping the eyelids apart during inspection of or operation on the eye. SYN: blepharostat. Kelly rectal s. a tubular s. with obturator for rectal examination. Pedersen s. a narrow flat s. used in vaginas with a narrow introitus. stop-s. a dilating s., as a s. of the eyelids, which is provided with a catch to prevent its being opened too wide.

Ferdinand Graf von, German embryologist, 1855–1937. See curve of S..

Gene that when mutated is responsible for motor dyspraxia.

Talk; the use of the voice in conveying ideas. [A.S. spaec] alaryngeal s. a form of s. achieved after laryngectomy by using either an external vibratory source or the pharyngoesophageal segment as an internal vibratory source. see also esophageal s.. Tracheoesophageal s. may be produced after laryngectomy by surgically diverting exhaled air to the pharynx by a permanently constructed tracheoesophageal fistula. cerebellar s. an explosive type of utterance, with slurring of words. clipped s. SYN: scamping s.. cued s. a system of communication with a person with profound hearing impairment in which handshapes are used to cue sounds to supplement spoken language. echo s. SYN: echolalia. esophageal s. a technique for speaking following total laryngectomy; consists of drawing air into the esophagus and regurgitating it, producing a vibration in the hypopharynx. explosive s. loud, sudden s. related to injury of the nervous system. SYN: logospasm (2) . helium s. the peculiar high-pitched, often unintelligible s. sounds produced when one breathes a mixture of up to 80° per cent helium and 20° per cent oxygen. mirror s. a reversal of the order of syllables in a word, analogous to mirror writing. scamping s. a form of lalling in which consonants or syllables that are difficult to pronounce are omitted. SYN: clipped s.. scanning s. measured or metered, often slow s. with interruptions. slurring s. slovenly articulation of the more difficult letter sounds. spastic s. labored s. related to increased tone of muscles. staccato s. an abrupt utterance, each syllable being enunciated separately; noted especially in multiple sclerosis. SYN: syllabic s.. subvocal s. slight movements of the muscles of s. related to thinking but producing no sound. syllabic s. SYN: staccato s.. tracheoesophageal s. a form of alaryngeal s. obtained by a surgical technique which creates a shunt between trachea and esophagus, allowing pulmonary air to generate upper esophageal and pharyngeal mucosal vibrations as a substitute for vocal cord vibrations when the larynx is surgically removed.

speed (sped)
The magnitude of velocity without regard to direction. Cf.:velocity.

spelencephaly (spe-len-sef′a-le)
SYN: porencephaly. [spelaion, cave, + enkephalos, brain]

Thomas, Scottish physician, 1769–1842. See S. syndrome.

SYN: spermatozoon. [G. sperma, seed]

sperma-, spermato-, spermo-
Semen, spermatozoa. [G. sperma, seed]

spermaceti (sper-ma-set′e)
A peculiar fatty, waxy substance, chiefly cetin (cetyl palmitate), obtained from the head of the sperm whale, Physeter macrocephalus; used to impart firmness to ointment bases. SYN: cetaceum. [sperma- + G. ketos, whale]

spermagglutination (sperm′a-gloo-ti-na′shun)
Agglutination of spermatozoa.


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