Medical Dictionary banner
Medical Dictionary - Dictionary of Medicine and Human Biology

Medical Dictionary


segmental (seg-men′tal)
Relating to a segment.

segmentation (seg′men-ta′shun)
1. The act of dividing into segments; the state of being divided into segments. 2. SYN: cleavage (1) .

segmentectomy (seg-men-tek′to-me)
Excision of an anatomic segment of any organ or gland.

segmenter (seg′men-ter)
A schizont; usually applied to the malaria parasite developing in a red blood cell after having undergone nuclear and cytoplasmic division, just before cell rupture and release of the merozoites.

Segmentina (seg-men-ti′na)
A genus of freshwater pulmonate snails (family Planorbidae, subfamily Segmentininae); includes the species S. hemisphaerula, an important intermediate host of Fasciolopsis buski. [L. segmentum, fr. seco, to cut]

segmentum, pl .segmenta (seg-men′tum, -ta) [TA]
SYN: segment (1) . [L. segment] s. A1 arteriae cerebri anterioris precommunicating part of anterior cerebral artery. s. A2 arteriae cerebri anterioris postcommunicating part of anterior cerebral artery. s. anterius [TA] SYN: anterior segment. s. apicale apical segment of the inferior lobe of the right and left lungs. s. bronchopulmonale [TA] SYN: bronchopulmonary segment. s. (bronchopulmonale) anterius S III [TA] SYN: anterior (bronchopulmonary) segment [S III]. s. bronchopulmonale apicale S I SYN: apical (bronchopulmonary) segment [S I]. s. (bronchopulmonale) basale laterale [S IX] SYN: lateral basal (bronchopulmonary) segment [S IX]. s. bronchopulmonale basale mediale S VII [TA] SYN: medial basal bronchopulmonary segment S VII. s. bronchopulmonale laterale S IV [TA] SYN: lateral bronchopulmonary segment S IV. s. bronchopulmonale lingulare superius[S IV] [TA] SYN: superior lingular bronchopulmonary segment S IV. s. bronchopulmonale mediale S V [TA] SYN: medial bronchopulmonary segment S V. s. bronchopulmonale posterius S II [TA] SYN: posterior bronchopulmonary segment S II. s. (bronchopulmonale) apicoposterius [SI + II] SYN: apicoposterior (bronchopulmonary) segment [SI + SII]. s. cardiacum SYN: medial basal bronchopulmonary segment S VII. segmenta cervicalia C1–C5 SYN: cervical part of spinal cord. segmenta cervicalia medullae spinalis [TA] SYN: cervical part of spinal cord. segmenta coccygea medullae spinalis [TA] SYN: coccygeal part of spinal cord. segmenta hepatis [TA] SYN: hepatic segments, under segment. s. hepatis anterius laterale dextrum [VI] [TA] SYN: right anterior lateral hepatic segment [VI]. s. hepatis anterius laterale sinistrum [III] [TA] SYN: (left anterior) lateral hepatic segment [III]. s. hepatis anterius mediale (dextrum) [V] [TA] SYN: (right) anterior medial hepatic segment [V]. s. hepatis mediale (sinistrum) [IV] [TA] SYN: (left) medial hepatic segment [IV]. s. hepatis posterius I [TA] SYN: posterior hepatic segment I. s. hepatis posterius laterale sinistrum [II] [TA] SYN: (left posterior) lateral hepatic segment III. s. hepatis posterius laterale (dextrum) [VII] [TA] SYN: (right) posterior lateral hepatic segment [VII]. s. hepatis posterius mediale (dextrum) [VIII] [TA] SYN: (right) posterior medial hepatic segment [VIII]. s. I posterior hepatic segment I. s. II (left posterior) lateral hepatic segment III. s. III (left anterior) lateral hepatic segment [III]. s. inferius [TA] SYN: inferior segment. s. internodale SYN: internodal segment. s. IV (left) medial hepatic segment [IV]. s. laterale [TA] SYN: lateral segment. segmenta lienis SYN: segments of spleen, under segment. s. lingulare bronchopulmonale inferius S V [TA] SYN: inferior lingular (bronchopulmonary) segment [S V]. segmenta lumbalia L1–L5 SYN: lumbar part of spinal cord. segmenta lumbalia medullae spinalis SYN: lumbar part of spinal cord. s. mediale [TA] SYN: medial segment. segmenta medullae spinalis C1–Co [TA] SYN: segments of spinal cord [C1–Co], under segment. segmenta medullae spinalis cervicalia C1–C8 [TA] SYN: cervical part of spinal cord. s. medullae spinalis coccygeum [Co] [TA] SYN: coccygeal segment of spinal cord [Co]. segmenta medullae spinalis lumbaria L1–L5 SYN: lumbar segments of spinal cord L1–5, under segment. s. oculare anterius [TA] SYN: anterior ocular segment. s. P4 arteriae cerebri posterioris medial occipital artery. s. P3 arteriae cerebri posterioris [TA] SYN: lateral occipital artery. s. P1 arteriae cerebri posterioris medial occipital artery. s. posterius [TA] SYN: posterior segment. s. renale anterius inferius SYN: anterior inferior renal segment. s. renale anterius superius SYN: anterior superior renal segment. s. renale inferius [TA] SYN: inferior renal segment. segmenta renalia [TA] SYN: renal segments, under segment. s. renale posterius [TA] SYN: posterior renal segment. s. renale superius [TA] SYN: superior renal segment. segmenta sacralia medullae spinalis [TA] SYN: sacral part of spinal cord. s. (bronchopulmonale) basale anterius [S VIII] SYN: anterior basal (bronchopulmonary) segment [S VIII]. s. subapicale SYN: subapical segment. s. subsuperius SYN: subapical segment. segmenta thoracica medullae spinalis [TA] SYN: thoracic part of spinal cord.

segregation (seg-re-ga′shun)
1. Removal of certain parts from a mass, e.g., those with infectious diseases. 2. Separation of contrasting characters in the offspring of heterozygotes. 3. Separation of the paired state of genes, which occurs at the reduction division of meiosis; only one member of each somatic gene pair is normally included in each sperm or ovum; e.g., an individual heterozygous for a gene pair, Aa, will form gametes half containing gene A and half containing gene a. 4. Progressive restriction of potencies in the zygote to the following embryo. [L. segrego, pp. -atus, to set apart from the flock, separate]

segregator (seg′re-ga-ter, tor)
SYN: separator (2) .

Erich, German ophthalmologist, 1882–1946. See S. scotoma, S. sign.

Pierre, French apothecary, 1660–1719. See S. salt.

Carl, Swiss laryngologist and anatomist in U.S., 1849–1905. See S. cartilage.

Martin, 20th century Scandinavian physician. See Lawrence-S. syndrome, S. syndrome.

seismocardiogram (siz′mo-kar′de-o-gram)
Recording of cardiac vibrations as they affect the entire body, by various techniques. [G. seismos, a shaking, + cardiogram]

seismotherapy (siz-mo-thar′a-pe)
SYN: vibratory massage. [G. seismos, a shaking, vibration]

seizure (se′zher)
1. An attack; the sudden onset of a disease or of certain symptoms. 2. An epileptic attack. SYN: convulsion (2) . [O. Fr. seisir, to grasp, fr. Germanic] absence s. a s. characterized by impaired awareness of interaction with, or memory of, ongoing events external or internal to the person; may comprise the following elements: mental confusion, diminished awareness of environment, inability to respond to internal or external stimuli, and amnesia. (The term absence was first used by Louis-Florentin Calmeil (1798–1895) to introduce the concept of epileptic absence for the brief loss of consciousness or confusion seen in epileptic patients.) akinetic s. SYN: atonic s.. anosognosic seizures SYN: anosognosic epilepsy. astatic s. s. causing loss of erect posture. atonic s. a s. characterized by sudden, brief (1–2 s.) loss of muscle tone, involving postural muscles; the term usually applies to bilaterally synchronous events. SYN: akinetic s.. atypical absence s. an absence s. associated with an EEG pattern of irregular or slow spike and wave at less than 2.5 Hz or paroxysmal fast activity on an abnormally slow background EEG. audiogenic s. a reflex s. precipitated by loud noises, rare in humans. Audiogenic seizures in rodents are an animal model of epilepsy. automotor s. s. characterized by an automatism predominantly involving the distal limbs. autonomic s. s. characterized by objectively documented dysfunction of the autonomic nervous system, usually involving cardiovascular, gastrointestinal, or sudomotor functions. clonic s. a s. characterized by repetitive rhythmical jerking of all or part of the body. complex motor s. s. characterized by muscles of each limb contracting asynchronously and sequentially to produce a movement that may resemble voluntary activity. complex partial s. a s. with impairment of consciousness, occurring in a patient with focal epilepsy. convulsive s. s. with clonic or tonic-clonic motor activity. dileptic s. s. characterized by impaired awareness of, interaction with, or memory of ongoing events. early s. a s. occurring within one week after craniocerebral trauma. electrographic s. SYN: subclinical s.. epileptic s. clinical and/or laboratory manifestations of an epileptic attack. febrile s. SYN: febrile convulsion. focal motor s. a simple partial s. with localized motor activity. gelastic s. a s. characterized by bursts of involuntary laughter or giggling, usually without an appropriate affective tone; most often related to hypothalamic lesions, such as hamartomas. generalized seizures seizures characterized by generalized clinical manifestations. generalized tonic-clonic s. a generalized s. characterized by the sudden onset of tonic contraction of the muscles often associated with a cry or moan, and frequently resulting in a fall to the ground. The tonic phase of the s. gradually give way to clonic convulsive movements occurring bilaterally and synchronously before slowing and eventually stopping, followed by a variable period of unconsciousness and gradual recovery. SYN: cryptogenic epilepsy, generalized tonic-clonic epilepsy, grand mal s., grand mal, idiopathic epilepsy (2) , major epilepsy. grand mal s. SYN: generalized tonic-clonic s.. hypermotor s. s. characterized by automatisms involving predominantly proximal limb muscles and producing marked limb displacement. hypomotor s. s. characterized by complete or partial arrest of ongoing motor activity in a patient whose level of consciousness cannot be determined accurately ( e.g., newborns, infants, mentally retarded patients). jacksonian s. a motor s. that initially involves one part of the body and then progressively spreads to other parts of the body on the same side; may become generalized; often originates in or near the contralateral rolandic neocortex. SYN: jacksonian epilepsy. late s. a s. that occurs greater than one week after a craniocerebral trauma or CNS insult. major motor s. a grand mal s. or other convulsive s.. minor motor s. old term for nonconvulsive s. seen in patients with secondary generalized epilepsies. myoclonic s. a s. characterized by sudden, brief (200-ms) contractions of muscle fibers, muscles, or groups of muscles of variable topography (axial, proximal, or distal limb). negative myoclonic s. s. characterized by abrupt, brief cessation of muscular activity, occasionally preceded by a single myoclonic contraction; term usually is applied to unilateral, distal muscles. nonconvulsive s. a s. without clonic or tonic activity or other convulsive motor activity. SEE ALSO: complex partial s., absence s.. nonepileptic s. any behavior that resembles a s., but is not epileptic, i.e., not associated with abnormal cerebral EEG activity. SEE ALSO: psychogenic s.. partial s. s. characterized by localized cerebral ictal onset. The symptoms experienced are dependent on the cortical area of ictal onset or s. spread. petit mal s. obsolescent term for a cerebral s. not manifested by tonic-clonic movements ( i.e., grand mal); formerly thought to be the clinical manifestation solely of a 3-s. spike in wave pattern, as seen on electroencephalography, but now known to be associated with several different EEG patterns. psychic s. a simple partial s. characterized by an attack of psychic phenomena such as a dreamy state, déjà vu, autonomic sensation or emotion; commonly, but not exclusively, associated with temporal lobe epilepsy. psychogenic s. a clinical spell that resembles an epileptic s., but is not due to epilepsy. The EEG is normal during an attack, and the behavior is often related to psychiatric disturbance, such as a conversion disorder. psychomotor s. a s. characterized by psychic manifestation, and a complex motor s.. See psychic s.. secondarily generalized tonic-clonic s. a generalized tonic-clonic s. that begins with a partial s. and evolves into a generalized tonic-clonic s.. simple partial s. a partial s. that is not associated with impairment of consciousness; seen in patients with focal epilepsy. subclinical s. a s. detected by EEG, which has no clinical correlate, i.e., an EEG s. alone. SYN: electrographic s.. tonic s. a s. characterized by a sustained increase in muscle tone, of abrupt or gradual onset and offset, lasting a few seconds to a minute, usually 10–20 s.; tonic seizures affecting proximal muscles bilaterally frequently lead to the adoption of a posture. tonic-clonic s. a s. characterized by a sequence consisting of a tonic-clonic phase; when generalized, constitutes what has been known as a “grand mal” s.. versive s. a s. characterized by sustained, forced conjugate ocular and cephalic and/or truncal deviation.

selaphobia (se-la-fo′be-a)
Rarely used term for a morbid fear of a flash of light. [G. selas, light, + phobos, fear]

Sven Ivar, Swedish radiologist, *1921. See S. technique.

selectin (sel-ek′tin)
A cell surface molecule involved in immune adhesion and cell trafficking. [L. se-ligo, pp. se-lectum, to sort, choose, + -in] E s. cell surface receptor produced by endothelium. L s. cell surface receptor produced by leukocytes. P s. cell surface receptor present on endothelium that is involved with neutrophil migration into inflamed tissue.

selection (se-lek′shun)
The combined effect of the causes and consequences of genetic factors that determine the average number of progeny of a species that attain sexual maturity; phenotypes that are lethal early in life ( e.g., Tay-Sachs disease), that cause sterility ( e.g., Turner syndrome), or that produce sterile progeny are selected against. When s. is used of individual pedigrees, other factors, notably variance of the number of progeny and number that survive to maturity, are important considerations; in large populations, these factors even out and the mean only is of importance. [L. se-ligo, to separate, select, fr. se, apart, + lego, to pick out] artificial s. interference by humans with natural s. by purposeful breeding of animals or plants of specific genotype or phenotype to produce a strain with desired characteristics; e.g., breeding of dairy cattle for high milk production. medical s. preservation, by medical care and treatment, of individuals of pathologic genotypes who would not otherwise reproduce, thus tending to increase the frequency of pathologic genes in the population; conversely, reduction of the frequency of pathologic genes by preventing reproduction of individuals of specified genotype by surgical sterilization or other means. natural s. “survival of the fittest,” the principle that in nature those individuals best able to adapt to their environment will survive and reproduce, while those less able will die without progeny, and the genes carried by the survivors will increase in frequency. This principle is heuristic rather than rigorous since it cannot be tested, the outcome being tautologous with the empirical definition of fitness. sexual s. a form of natural s. in which, according to Darwin theory, the male or female is attracted by certain characteristics, form, color, behavior, etc., in the opposite sex; thus modifications of a special nature are brought about in the species.

selegiline (se-lej′e-len)
A monoamine oxidase enzyme inhibitor; inhibits only the type B isozyme so that consuming tyramine-containing foods or beverages is less likely to induce hypertensive crisis in persons treated with s. than in persons treated with nonselective monoamine oxidase inhibitors. The drug is used in the treatment of Parkinson disease. SYN: deprenyl.

selene unguium (se-le′ne ung′gwi-um)
SYN: lunule of nail. [G. selene, moon; gen. pl. of L. unguis, nail]

selenium (Se) (se-le′ne-um)
A metallic element chemically similar to sulfur, atomic no. 34, atomic wt. 78.96; an essential trace element toxic in large quantities; required for glutathione peroxidase and a few other enzymes; 75Se (half-life equal to 119.78 days) is used in scintography of the pancreas and parathyroid glands. [G. selene, moon] s. sulfide a mixture of crystalline s. monosulfide and solid solutions of s. and sulfur in an amorphous form, containing 52–55.5% Se; used in the treatment of seborrhea of the scalp or dandruff; it is applied to the scalp as a suspension.

selenocysteine (se-le-no-sis′ten)
Cysteine containing selenium in place of one sulfur atom.

selenodont (se-le′no-dont)
Denoting an animal, or humans, having teeth, as the human molars, with longitudinal crescent-shaped ridges. [G. selene, moon, + odous (odont-), tooth]

selenomethionine (se-le′no-me-thi′o-nen)
Methionine containing selenium in place of sulfur.

Selenomonas (se-le′no-mo′nas)
A genus of bacteria of uncertain taxonomic affiliation, containing curved to crescentic or helical, Gram-negative, strictly anaerobic rods that are motile with an active tumbling motion. Several flagella are present in a tuft, often near the center of the concave side. The type species, S. sputigena, is found in the human buccal cavity. [G. selene, moon, + monas, single (unit)]

1. A sum of the attitudes, feelings, memories, traits, and behavioral predispositions that make up the personality. 2. The individual as represented in his or her own awareness and in his or her environment. 3. In immunology, an individual's autologous cell components as contrasted with non-s., or foreign, constituents; the basic mechanism underlying recognition of s. from non-s. is unknown, but serves to protect the host from an immunologic attack on the host's own antigenic constituents, as opposed to immune system destruction or elimination of foreign antigens. subliminal s. the sum of the mental processes which take place without the conscious knowledge of the individual. SYN: subconscious mind.

A common psychiatric symptom, encountered most characteristically in agitated depression.

SYN: autoanalysis.

Realization of one's ongoing feeling and emotional experience; a major goal of all psychotherapy.

SYN: autosynnoia.

Voluntary mental hospitalization.

1. Self-regulation of one's behavior in accordance with personal beliefs, goals, attitudes and societal expectations. 2. Use by an individual of active coping strategies to deal with problem situations, in contrast to passive conditioning strategies which do things to the individual and require no action by the person.

Differentiation resulting from the action of intrinsic causes.

In psychoanalysis, the freeing of the repressed ego in a person raised to be submissive to those around him.

An individual's estimate or personal judgment of his or her own ability to succeed in reaching a specific goal, e.g., quitting smoking or losing weight, or a more general goal, e.g., continuing to remain at a prescribed weight level.

Fecundation of the ovules by the pollen of the same flower, or of the ova by the spermatozoa of the same animal in hermaphrodite forms; denoting an extreme type of inbreeding seen in certain plants and animal forms which produce both male and female gametes.

SYN: autoinfection.

SYN: autognosis.

Denoting a disease that tends to cease after a definite period; e.g., pneumonia.

SYN: narcissism.

SYN: autointoxication.

A three-stage strategy patients are taught to use in order to end risky health-associated behaviors such as smoking and overeating: 1. self-monitoring (self-observation), the first stage in s. involves the individual's deliberately attending to and recording his or her own behavior; 2. self-evaluation, the second stage, in which the individual assesses what was learned by self-monitoring, such as how often and where one smokes, and uses those observational data to establish health goals or criteria; and 3. self-reinforcement, the third stage, in which the individual rewards him/herself for each behavioral success on the road to that goal, thereby enhancing the chance of reaching it.

A technique for electrical stimulation of peripheral nerves, spinal cord, or brain by the patient to relieve pain.

SYN: horror autotoxicus.

Feodor, Russian chemist, *1859. See S. test.

sella (sel′a)
SYN: saddle (1) . [L. saddle] empty s. a s. turcica, often enlarged, that contains no discernible pituitary gland; may be primarily due to an incompetent sellar diaphragm with compression of the pituitary gland by herniating arachnoid or secondarily due to surgery or radiotherapy. s. turcica [TA] a saddlelike bony prominence on the upper surface of the body of the sphenoid bone, constituting the middle part of the butterfly-shaped middle cranial fossa; it includes the tuberculum sellae anteriorly and the dorsum sellae posteriorly; with its covering of dura mater it constitutes the hypophysial fossa that accommodates the hypophysis or pituitary gland. SYN: pars sellaris, Turkish saddle.

sellar (sel′ar)
Relating to the sella turcica.

Brian A., 20th century British anesthetist. See S. maneuver.

Hans, Austrian endocrinologist in Canada, 1907–1982. See adaptation syndrome of S..

Abbreviation for standard error of the mean.

semantics (se-man′tiks)
A branch of semiotics: 1. The study of the significance and development of the meaning of words. 2. The study concerned with the relations between signs and their referents; the relations between the signs of a system; and human behavioral reaction to signs, including unconscious attitudes, influences of social institutions, and epistemological and linguistic assumptions. [G. semaino, to show]

Georges, 20th century French pediatrician. See Debré-S. syndrome, Kocher-Debré-S. syndrome.

semelincident (sem-el-in′si-dent)
An obsolete term that means happening once only; said of an infectious disease, one attack of which confers permanent immunity. [L. semel, once, + incido, to happen, fr. cado, to fall]

semen, pl .seminasemens (se′men, se-mi′na, se′menz)
1. [NA] The penile ejaculate; a thick, yellowish-white, viscid fluid containing spermatozoa; a mixture produced by secretions of the testes, seminal vesicles, prostate, and bulbourethral glands. SYN: seminal fluid. 2. SYN: seed (1) . [L. s. (semin-), seed (of plants, men, animals)]

semenuria (se-me-noo′re-a)
The excretion of urine containing semen. SYN: seminuria, spermaturia.

One-half; partly. Cf.:hemi-. [L. semis, half]

semialdehyde (sem-e-al′de-hid)
The monoaldehyde of a dicarboxylic acid, so called because half the COOH groups of the original acid are reduced to the aldehyde while the other half are unchanged; e.g., glutamic acid γ-s., OHC–CH2CH2CH(NH3)+–COO−. Many semialdehydes are intermediates in the biosynthesis and metabolic degradation of amino acids ( e.g., l-proline, l-lysine, l-glutamate).


. . . Feedback