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

sebaceous gland
a type of holocrine gland of the dermis that secretes an oily material (sebum) into the hair follicles.

sebaceous horn
a hard outgrowth of the contents of a sebaceous cyst.

sebaceous hyperplasia
single or multiple pale, round lesions, consisting of enlarged, malformed sebaceous glands, usually on the face of an older adult. Called also sebaceous adenoma.

sebaceous nevus
an epidermal nevus of the scalp or less often the face, present at birth, with hyperplastic sebaceous glands and hair follicles. The size can vary considerably, and many grow larger during puberty or early adult life. In later life, some lesions may give rise to a variety of new growths, including basal cell carcinoma.

sebaceous nevus syndrome
a syndrome characterized by a sebaceous nevus or nevi in a linear formation, present at birth and changing progressively throughout life. Some patients have neurologic symptoms (retardation or seizures) or ophthalmologic abnormalities. After puberty the nevi become thickened and verrucous, often with projections and numer...

seborrhea
(seb″o-re´ә) excessive discharge from the sebaceous glands, forming greasy scales or cheesy plugs on the body; it is generally accompanied by itching or burning. adj., seborrhe´ic., adj. seborrhea sicca dry, scaly seborrheic dermatitis.

seborrheic dermatitis
an inflammatory condition, usually of the skin of the scalp, with yellowish greasy scaling of the skin and itching. A mild case in the scalp is called dandruff. The condition can involve other areas such as the face, neck, central part of the trunk, or armpit. The underlying cause is not known; the hair and scalp are some...

seborrheic keratosis
a common, usually benign type of skin lesion, usually first appearing after age 30 and presenting as a soft, friable plaque with variable pigmentation. The most common sites are the face, trunk, and limbs.

sebotropic
(seb″o-tro´pik) having an affinity for sebaceous glands.

sebum
(se´bәm) the oily secretion of the sebaceous glands, whose ducts open into the hair follicles. It is composed of fat and epithelial debris from the cells of the malpighian layer, and it lubricates the skin.

Seckel syndrome
(sek´әl) a syndrome of unknown etiology, characterized by intrauterine growth retardation and postnatal dwarfism with a small head, narrow birdlike face with a beaklike nose, large eyes with an antimongoloid slant, receding mandible, and mild mental retardation. Called also bird-headed dwarfism, Seckel dwarfism, a...

secobarbital
(sek″o-bahr´bĭ-tәl) a short-acting barbiturate used as the sodium salt as a sedative and hypnotic, particularly as a presurgical aid to anesthesia, and as an anticonvulsant in the treament of tetanus.

Seconal
(sek´o-nahl) trademark for preparations of secobarbital sodium, a sedative and hypnotic.

second
(s) (sek´әnd) the base SI unit of time, equal to 1/60 of a minute, and defined in terms of the periodicity of specific radiation of cesium 133.

second degree heart block
the partial form of heart block, in which some impulses are not conducted; often used specifically for second degree atrioventricular block. Called also partial heart block.

second impact syndrome
acute, usually fatal, brain swelling and increased cranial pressure, caused by repeated head trauma in a short space of time, so that a second concussion occurs before recovery from a previous concussion is complete.

second posterior intercostal artery
origin,supreme intercostal artery; branches, dorsal and spinal branches; distribution, upper thoracic wall.

second set phenomenon
the accelerated and intensified rejection by the recipient of a second graft of tissue from the same donor as a consequence of the primary immune response (i.e., antibody production and cell-mediated immunity) induced by the first graft.

second stage of labor
see labor.

second-degree burn
a burn that affects the epidermis and the dermis, classified as superficial or deep according to the depth of injury. The superficial type involves the epidermis and the upper part of the dermis and is characterized by pain, edema, and the formation of blisters; it heals without scarring. The deep type extends into the lower pa...

secondary amenorrhea
cessation of menstruation after it has once been established at puberty. The most common cause of this is pregnancy, but if that is excluded, there is usually a disturbance of the endocrine glands concerned with the menstrual process.

secondary amyloidosis
amyloidosis in which the deposited fibrillar material is AA amyloid; this is secondary to a chronic inflammatory condition, either infectious (such as tuberculosis or osteomyelitis) or noninfectious (such as rheumatoid arthritis or Crohn disease). It usually affects the kidneys, spleen, and liver. Called also AA amyloidosis.

secondary apnea
a period of time following primary apnea during which continued asphyxia of the fetus or newborn, with a fall in blood pressure and heart rate, necessitates artificial ventilation for resuscitation and reestablishment of ventilation.

secondary atelectasis
congenital atelectasis in which resorption of the contained air has led to collapse of the alveoli. acquired atelectasis.

secondary attack rate
the attack rate in a closed exposed group, such as a household. The index case, which brings the group to the attention of the investigator, and also other initial cases occurring too early to be related to the index case are excluded from both the numerator and the denominator when possible.

secondary biliary cirrhosis
a type due to chronic bile obstruction from either congenital atresia or a stricture.

secondary brain vesicles
the four brain vesicles formed by specialization of the forebrain and of the hindbrain in later embryonic development.

secondary cardiomyopathy
any form that is due to another cardiovascular disorder or is a manifestation of a systemic disease such as sarcoidosis.

secondary care
treatment by specialists to whom a patient has been referred by primary care facilities. acute care.

secondary cataract
a cataract, usually posterior subcapsular, caused by either a disease such as iridocyclitis, a degenerative condition such as glaucoma or retinal detachment, or complication from surgery such as glaucoma filtering or retinal reattachment.

secondary disease
(sek´un-der″e) a morbid condition subsequent to or a consequence of another disease. a condition due to introduction of incompatible, immunologically competent cells into a host rendered incapable of accepting them by heavy exposure to ionizing radiation.

secondary dysmenorrhea
any of the types caused by pelvic pathology that may include endometriosis, pelvic inflammatory disease, or prolapse of the uterus. See also premenstrual syndrome.

secondary fracture
pathologic fracture.

secondary glaucoma
glaucoma resulting from some other condition, such as uveitis, neoplastic disease, trauma, or degenerative changes in the eye.

secondary host
intermediate host.

secondary impotence
impotence in a man who previously experienced normal penile function.

secondary infection
infection by a second pathogen after infection by one of another kind.

secondary lymphedema
any of the types whose cause is known, such as elephantiasis or types caused by trauma, scarring, or surgery (especially mastectomy).

secondary nystagmus
nystagmus occurring after the abrupt cessation of rotation of the head, caused by the labyrinthine fluid continuing to move.

secondary optic atrophy
a form in which the optic disk is characterized by blurred margins, poor visibility of the lamina cribrosa, filling-in of the physiologic cup, and gray-white glial tissue on its surface and along its blood vessels; called also gray atrophy.

secondary pacemaker
ectopic pacemaker.

secondary pneumonia
pneumonia seen as a complication of some other disorder, such as influenza or a fungal infection.

secondary polycythemia
any absolute increase in the total red cell mass other than polycythemia vera, usually occurring as a response to hypoxia (deficient oxygen supply to the tissues). Some types are called compensatory or appropriate, such as from adjustments for general tissue hypoxia (such as that associated with lung disease, heart disease, or living...

secondary sensory neuron
a sensory neuron that is the second in an afferent pathway, being stimulated at a synapse by a primary sensory neuron and often extending some distance into the central nervous system.

secondary suture
delayed closure of an operative or accidental wound, usually because of the presence or expectation of infection. resuture of an operative wound following disruption.

secondary syphilis
a stage that begins two to six months after the primary sore has disappeared, and may last up to two years. An early symptom is a rash that may cover part or all of the body surface; it does not itch and may resemble the rash of measles. During secondary syphilis, thin white sores may appear on the mucous membranes inside...

secondary tuberculosis
postprimary tuberculosis.

secretagogue
(se-krēt´ә-gog) causing a flow of secretion. an agent that so acts.

secretary
(sek´rĕ-tar″e) a person employed to do clerical work such as handling of correspondence, keeping of files, and similar duties. unit secretary ward clerk.

secrete
(se-krēt´) to synthesize and release a substance.

secretin
(se-kre´tin) a hormone secreted by the mucosa of the duodenum and jejunum when acid chyme enters the intestine; carried by the blood, it stimulates the secretion of pancreatic juice and, to a lesser extent, bile and intestinal secretion.

secretin injection test
secretin test.

secretin stimulation test
secretin test.

secretin test
an examination of the gastric and duodenal contents after intravenous administration of exogenous secretin; useful in diagnosis of disorders affecting pancreatic exocrine function, such as pancreatitis and neoplastic disease; specimens are analyzed for output (secretory rate), bicarbonate concentration, and amylase activity.

secretin-cholecystokinin test
(for pancreatic function) a combination of the secretin test and the cholecystokinin test, measuring pancreatic secretion volume and secretion of bicarbonate, amylase, lipase, and trypsin. Called also secretin-pancreozymin test.

secretin-pancreozymin test
secretin-cholecystokinin test.

secretion
(se-kre´shәn) the cellular process of elaborating a specific product. This activity may range from separating a specific substance of the blood to the elaboration of a new chemical substance. material that is secreted, such as sebum, saliva, and gastric juice. The secretions of the endocrine glands i...

secretoinhibitory
(se-kre″to-in-hib´ĭ-tor″e) antisecretory.

secretomotor
(se-kre″to-mo´tәr) stimulating secretion; said of nerves.

secretor
(se-kre´tәr) an individual expressing the autosomal dominant phenotype of secreting the ABH antigens of the ABO blood group in the saliva and other body fluids. the gene determining this phenotype.

secretory
(se-kre´tә-re) (se´krә-tor″e) pertaining to secretion.

secretory duct
a smaller duct that is tributary to an excretory duct of a gland and that also has a secretory function.

secretory nerve
any efferent nerve whose stimulation increases glandular activity.

secretory otitis media
serous otitis media.

secretory phase
the phase of the uterine cycle, corresponding to the luteal phase of the ovarian cycle, during which the endometrium, under the influence of progesterone and estrogen from the corpus luteum, thickens and the spiral arteries increase in prominence and become longer and more coiled, with the development of large venous lacunae.

section
(sek´shәn) an act of cutting. a cut surface. a segment or subdivision of an organ.

sectorial
(sek-tor´e-әl) cutting.

Sectral
(sek´tral) trademark for a preparation of acebutolol hydrochloride, used in treatment of hypertension, arrhythmias, and angina pectoris.

secundigravida
(sә-kun″dĭ-grav´ĭ-dә) a woman pregnant the second time; gravida II.

secundines
(sek´әn-dēnz) (se-kun´dēnz) afterbirth.

secundipara
(se″kәn-dip´ә-rә) a woman who has had two pregnancies that resulted in viable offspring; para II.

sedation
(sә-da´shәn) the allaying of irritability or excitement, especially by administration of a sedative. the state so induced. conscious sedation a state of sedation in which the conscious patient has been given a medication that makes him or her free of fear and anx...

sedative
(sed´ә-tiv) decreasing irritability, excitement, or nervousness. an agent that does this. The usual mode of action is depression of the central nervous system, which tends to reduce mental activity. Sedatives are distinct from tranquilizers, which also have a calming effect but usually do not suppres...

sedentary
(sed´әn-tar″e) of inactive habits; pertaining to a sitting posture.

Sédillot operation
a flap operation for restoring the upper lip.

sediment
(sed´ĭ-mәnt) a precipitate, especially that formed spontaneously.

sedimentation
(sed″ĭ-mәn-ta´shәn) the settling out of sediment; see also sedimentation rate.

sedimentation coefficient
the velocity at which a particle sediments in a centrifuge divided by the applied centrifugal field, the result having units of time (velocity divided by acceleration), usually expressed in Svedberg units (S), which equal 10−13 second. Sedimentation coefficients are used to characterize the size of macromolecules; they in...

sedimentation rate
the rate at which a sediment is deposited in a given volume of solution, especially when subjected to the action of a centrifuge; see also erythrocyte sedimentation rate.

seed
(sēd) the mature ovule of a flowering plant. semen. a small cylindrical shell of gold or other suitable material, used in application of radiation therapy. to inoculate a culture medium with microorganisms. plantago seed , psyllium seed ...

Seessel pouch
an outpouching of the pharynx of the embryo, above the pharyngeal membrane and below the Rathke pouch.

Segawa syndrome
(sĕ-gah´wah) dopa-responsive dystonia.

segment
(seg´mәnt) a demarcated portion of a whole. adj., segmen´tal., adj. behavior segment the smallest descriptive unit of a response to a stimulus. bronchopulmonary segments the smaller subdivisions of the lobe of a lung; each segment is separate...

segmental anesthesia
loss of sensation in a segment of the body due to a lesion of a nerve root.

segmental aneusomy syndrome
contiguous gene syndrome.

segmental arteries of kidney
a group of arteries originating from the anterior or posterior branch of the renal artery, consisting of anterior inferior, anterior superior, inferior, posterior, and superior segmental arteries; each supplies the corresponding renal segment.

segmental arteries of left lung
branches of the left pulmonary artery that supply segments of the left lung. The arteries are variable but often include lingular arteries and anterior, apical, posterior, superior, anterior basal, lateral basal, medial basal, and posterior basal segmental arteries, which are named for the segment supplied.

segmental arteries of liver
a group of arteries originating from the right or left branch of the hepatic artery proper, consisting of anterior, posterior, medial, and lateral segmental arteries; each supplies the corresponding region of the liver.

segmental arteries of right lung
branches of the right pulmonary artery that supply segments of the right lung. The arteries are variable but often include anterior, apical, medial, lateral, posterior, superior, anterior basal, lateral basal, medial basal, and posterior basal segmental arteries, which are named for the segment supplied.

segmental atelectasis
lobar atelectasis.

segmental dystonia
focal dystonia in two or more muscles that are next to each other.

segmental fracture
double fracture.

segmental mastectomy
partial mastectomy.

segmental medullary artery
one of the spinal branches of the vertebral artery, of the dorsal branch of a posterior intercostal artery, or of a lumbar artery; it supplies the root of a particular spinal nerve and extends to join with the anterior spinal artery.

segmental reflex
a reflex controlled by a single segment or region of the spinal cord.

segmental spinal artery
any artery that supplies, or that provides a branch supplying, one or more segments of the vertebral canal, including the vertebral, ascending cervical, posterior intercostal, subcostal, iliolumbar, lumbar, and lateral sacral arteries.

segmental zone
a zone of undifferentiated mesoderm between somites already formed and the primitive node, from which additional somites will be produced.

segmentary syndrome
a syndrome produced by a lesion of the gray matter of the spinal cord, and marked by weakness and wasting in the affected segment; called also metameric syndrome.

segmentation
(seg″mәn-ta´shәn) division into similar parts. cleavage.

segmentation contraction
segmentation movement one of the movements of the small intestine in digestion, consisting of small, irregular or rhythmic, circular contractions that segment a portion of the intestine into evenly spaced parts resembling a string of sausages. See also pendular m.