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Medical Dictionary - Letter: s

s-t segmentThe segment on an EKG tracing that represents the interval between the end of ventricular depolarization and the beginning of ventricular repolarization.
s.o.s.if necessary
S1first heart sound
S2second heart sound
S3third heart sound
S4fourth heart sound
sacA bag-like structure.
saccadesAn abrupt voluntary shift in ocular fixation from one point to another, as occurs in reading.
sacculeOne of the two membranous sacs within the vestibule of the inner ear. It contains fluid, responses to gravity and provides the brain with information about head position.
sacr/osacrum (large bone at base of spine)
sacroiliitisInflammation of the sacroiliac joint, marked by lower back pain, fever, uveitis, psoriasis and decreased range of motion.
sacrumThe large, triangular bone at the dorsal part of the pelvis, between the two hip bones. The sacrum strengthens and stabilizes the pelvis.
SADseasonal affective disorder
sadismA condition in which there is pleasure from inflicting pain, discomfort or humiliation on another person.
sagittalA plane that extends down the long axis of the body, parallel to the median plane.
sagittal planeseparates the body's left and right sections
salicylismPoisoning by salicylic acid or its compounds.
salivaThe clear, viscous fluid secreted by the salivary glands and mucous glands of the mouth. It serves to moisten the oral cavity, to initiate the digestion of starches, and to aid in the chewing and swallowing of food.
salivary ductsAny of the ducts which transport saliva.
salivary glandsGlands that secrete saliva in the mouth. There are three pairs of salivary glands: parotid gland; sublingual gland and submandibular gland.
salmonellaA genus of gram-negative, rod-shaped bacteria. It causes food poisoning, enteric fevers, gastroenteritis, and bacteremia.
salping/ofallopian tube
salpingitisInflammation of the fallopian or eustachian tube.
salpingostomyFormation of an artificial opening in a fallopian tube.
salvage therapyA therapeutic approach, involving chemotherapy, radiation therapy, or surgery, after initial regimens have failed to lead to improvement in a patient's condition. Salvage therapy is most often used for neoplastic diseases.
sanatoriumA facility for the treatment of chronic disorders.
sanguineousPertaining to blood.
sarc/oflesh, connective tissue
sarcocystosisInfection of the striated muscle of mammals by parasites of the genus Sarcocystis. Often asymptomatic, but symptoms include vomiting, diarrhea, muscle weakness, and paralysis.
sarcoidA fleshy tumor.
sarcoidosisAn disease that leads to inflammation, usually in the lungs, skin, or lymph nodes. Characterized by the formation of granulomas which contain giant cells.
sarcomaA cancer of the bone, muscle, cartilage, fat, blood vessels or connective tissue.
-sarcomacancer of connective tissue
sarcopeniaA disease associated with aging resulting in loss of muscle mass and strength.
SARSsevere acute respiratory syndrome
sartoriusThe thin, long, diagonal, strap-like anterior thigh muscle extending from the pelvis to the calf of the leg.
satiationA fulfillment of a need or desire followed by a state of relative insensitivity to that particular need or desire.
SBsmall bowel
SBOsmall bowel obstruction
SBPsystolic blood pressure
scabiesItchy skin caused by a tiny burrowing mite. Symptoms worse at night.
scalpThe outer covering of the calvaria. It is composed of several layers: skin, subcutaneous connective tissue, the occipitofrontal muscle , loose connective tissue and the pericranium.
scaph/oboat-shaped, scapha
scaphoid boneThe bone which is located most lateral in the proximal row of carpal bones.
scapul/oscapula (shoulder blade)
scapulaThe flat triangular bone in the back of the shoulder. Also called the shoulder blade.
scarA permanent mark remaining after a wound heals.
scarlet feverAn acute contagious bacterial disease of childhood characterized by tonsillitis and pharyngitis as well as fever, chills, nausea, headache, abdominal pain, malaise and rash.
-schisiscleft, split
schisto-split, cleft
schizophreniaA chronic, severe mental illness that interferes with the ability to think, manage emotions, make decisions and relate to others.
sciatic nerveA nerve which originates in the lumbar and sacral spinal cord and supplies motor and sensory innervation to the lower extremity. The sciatic nerve is the largest nerve in the body.
sciaticaPain radiating along the sciatic nerve from the lower back down the leg.
scirrh/ohard, hard tumor
scler/owhite of eye, hard
scleraThe white, opaque, fibrous, outer envelope of the eyeball, covering it entirely except the cornea.
scleritisA severe, vision-threatening inflammation of the white part of the eye.
sclerodermaAn autoimmune, chronic disease that affects the body by hardening connective tissue.
sclerosisA pathological process consisting of hardening or fibrosis of an anatomical structure, often a vessel or a nerve.
-sclerosisabnormal hardening
scoli/ocurved, crooked
scoliosisA sideways curvature of the spine that occurs most often during the growth spurt just before puberty.
-scopeinstrument used to view
-scopyprocess of viewing
scotomaAn area of diminished vision within the visual field.
scotopicPertaining to the adjustment of the eye to low illumination.
scrofulaTuberculosis affecting the lymph nodes, particularly the neck.
scrotumA pouch of skin containing the testicles and spermatic cords.
scurvyAn acquired blood vessel disorder caused by severe deficiency of vitamin C, characterized by spongy, bleeding gums, bleeding under the skin, and extreme weakness.
SDATstandard deviation
seb/osebum, oil, fatty
sebaceous glandsSmall, sacculated organs found within the dermis. Each gland has a single duct that opens into a hair follicle or onto the general surface of the skin. These glands secrete sebum, an oily lubricating substance.
seborrheaA common skin problem that causes a red, itchy rash and white scales. On the scalp, it is called dandruff.
sebumThe oily substance secreted by sebaceous glands. It is composed of keratin, fat, and cellular debris.
sect-dissect, cut
sedationThe reduction of anxiety, stress or excitement by administration of a sedative drug.
sedativeA drug that calms and relieves anxiety.
sedentary lifestyleUsual level of physical activity that is less than 30 minutes of moderate-intensity activity on most days of the week.
seizureA sudden surge of the brain’s electrical activity affecting movement and awareness for a short time.
seizuresA sudden attack, spasm, or convulsion.
semanticsStudy of the meanings of words (or symbols) and the rules of their use.
semenThe thick, yellowish-white, viscid fluid secretion of male reproductive organs discharged upon ejaculation. It contains spermatozoa and their nutrient plasma and secretions from the prostate and bulbourethral glands.
semicircular canalsThree long canals (anterior, posterior, and lateral) of the bony labyrinth. They are set at right angles to each other and are concerned with balance.
semih.half an hour
semilunar valveEither the aortic valve or the pulmonary valve, each consisting of crescent-shaped cusps.
seminomaA malignant neoplasm of the testis.
senescenceThe process of growing old.
sensationA perception produced by afferent nerve impulses conveyed to the sensorium.
sensitivityThe probability that a person having a disease will be correctly identified by a clinical test.
sensorineural hearing lossLoss of hearing resulting from problems in the inner ear. A common hearing impairment.
sepsisA serious medical condition caused by an overwhelming immune response to infection that triggers widespread inflammation. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock.
-sepsisdecay caused by
sept/oseptum, seven
septal defectA hole in the septum of the heart, usually congenital.
septicemiaA serious bacterial bloodstream infection. It’s also known as bacteremia, or blood poisoning.
sequelaAny disorder that results from a preceding disease or accident.
ser/oblood serum
seromaTumor-like sterile accumulation of serum in a tissue, organ, or cavity. It most commonly occurs following mastectomy.
seropusPus diluted with serum.
serositisInflammation of a serous membrane.
serotoninA compound widely distributed in the tissues that mediates important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity.
serous membraneA thin layer of tissue that covers a surface, cavity or divides a space. It consists of a single layer of squamous epithelial cells (mesothelium) resting on a thin layer of connective tissue, and covered with secreted clear fluid from blood and lymph vessels. Major serous membranes in the body include pericardium; peritoneum; and pleura.
serratiaA genus of gram-negative, rod-shaped bacteria that occurs in soil, water and plant surfaces or as an opportunistic human pathogen.
serumBlood plasma after the removal of clotting proteins.
sesamoidDenoting a small nodular bone embedded in a tendon or joint capsule and that slides over another bony surface. The patella is a sesamoid bone.
sesqui-one and one-half
sexThe totality of characteristics of reproductive structure, functions, phenotype, and genotype, differentiating the male from the female organism.
sexualityThe sexual functions, activities, attitudes, and orientations of an individual. Sexuality, male or female, becomes evident at puberty under the influence of gonadal steroids (testosterone or estradiol) and social effects.
SGAsmall for gestational age
shaken baby syndromeBrain injuries resulted from vigorous shaking of an infant or young child held by the chest, shoulders, or extremities causing extreme cranial acceleration. It is characterized by the intracranial and intraocular hemorrhages with no evident external trauma. Serious cases may result in death.
sheathA tubular casing that envelops structures such as arteries, nerves, tendons and muscles.
shin splintInflammation of the muscles, tendons, and bone tissue around the tibia.
shiveringInvoluntary contraction or twitching of the muscles due to cold or fear.
shockAn emergency pathological condition manifested by failure to perfuse or oxygenate vital organs and tissues.
shoulderThe junction of the clavicle, scapula, and humerus where the arm connects to the trunk.
shoulder dislocationDisplacement of the humerus from the scapula.
shuntA passage connecting two anatomical sites or channels.
SIinternational system of units
SIADHsyndrome of inappropriate diuretic hormone
sialaden/osalivary gland
sialadenitisInflammation of a salivary gland.
sialomucinsA subcategory of mucins that contain sialic acid.
sialorrheaExcessive salivary flow.
sibilantA high pitched hissing or whistling sound heard while auscultating.
sickle cell anemiaAn inherited form of anemia where red blood cells become rigid, sticky and shaped like sickles. These irregularly shaped cells can get stuck in small blood vessels, which can slow or block blood flow to parts of the body.
SICUsurgical intensive care unit
siderosisA form of pneumoconiosis resulting from inhalation of iron in mining dust or welding fumes.
SIDSsudden infant death syndrome
Sigwrite on label
sigmoidThe distal part of the colon from the level of the iliac crest to the rectum.
sigmold/osigmoid colon
signObjective evidence of a disease.
sign languageA system of hand gestures used for communication by the deaf or by people speaking different languages.
signs and symptomsClinical manifestations that can be either objective when observed by a physician, or subjective when perceived by the patient.
silic/osilica, quartz
silicosisA form of pneumoconiosis resulting from prolonged inhalation of silica dust.
simplexvirusA genus of the family herpesviridae, consisting of herpes simplex-like viruses.
simvastatinA statin used to treat high blood cholesterol levels.
sinoatrial blockThe electrical impulse from the sinoatrial node is inhibited or completely blocked before it reaches the atrium.
sinoatrial nodeThe small mass of modified cardiac muscle fibers located in the upper part of the right atrium. Contraction impulses are generated at the SA node and spread over the atrium, then transmitted by the Bundle of HIS to the ventricles.
sinus rhythmA normal heart rhythm as indicated on an EKG tracing.
sinusitisInflammation of the sinuses.
sito-bread, food
skeletonThe rigid framework of connected bones that gives form to the body, protects and supports its soft organs and tissues and provides attachments for muscles.
skinThe tough, supple, outer covering of the body that protects it from the environment. It is the largest organ of the body and is composed of the dermis and the epidermis.
skullThe skeleton of the head including the facial bones and the bones enclosing the brain.
SLEsystemic lupus erythematosus
sleepPhysiologic state of rest, relative unconsciousness and inaction of voluntary muscles.
sleep apneaSleep disorder characterized by multiple starts and stops of breathing, interfering with normal sleeping patterns. Measurable decrease in blood oxygen levels.
slingA bandage that supports an injured limb.
sloughNecrotic tissue separated from living tissue.
smallpoxAn acute, highly contagious, often fatal infectious viral disease characterized by fever and skin eruptions. It has been eradicated by vaccination programs worldwide.
smearA tissue specimen smeared on a microscopic slide.
smellThe ability to detect scents or odors, such as the function of olfactory receptor neurons.
sneezingThe sudden, forceful, involuntary expulsion of air from the nasal cavities and mouth due to irritation to the mucous membranes of the upper respiratory tract.
SNFskilled nursing facility
snoringNoisy breathing during sleep, due to vibration of the soft palate and other soft tissue in the upper airway.
snow blindnessA painful eye condition caused by exposure of insufficiently protected eyes to ultraviolet (UV) rays. Also called photokeratitis.
SOAPsubjective, objective, assessment, plan
SOBshortness of breath
socio-social, society
soleusA flat, broad muscle in the calf of the leg.
solutionA homogeneous mixture formed by the mixing of a solid, liquid, or gaseous substance with a liquid (the solvent) in which the substances are completely dispersed.
solventA liquid that dissolves other substances (solutes), generally solids.
somaThe body as distinguished from the mind or germ cells.
somaticPertaining to the body.
somatotrophsAnterior pituitary cells which produce growth hormone.
somatotypesCategories of body build determined on the basis of certain physical characteristics. The three basic body types are ectomorph (thin physique), endomorph (rounded physique), and mesomorph (athletic physique).
somnambulismA parasomnia characterized by a partial arousal that occurs during stage IV of non-REM sleep. Also called sleep-walking.
souffleA soft blowing sound heard with a stethoscope.
-spadiato tear, cut
spasmAn involuntary contraction of a muscle or group of muscles.
-spasmsudden, involuntary muscle contraction
spasmodic torticollisA very painful condition in which neck muscles contract involuntarily causing the head to twist, bend or rotate to one side.
specific gravityThe ratio of the density of a material to water at 4 degrees C.
specificityThe probability that a person who does not have a disease will be correctly identified by a clinical test.
spectrometryMeasurement of the wavelengths of electromagnetic emissions.
speechUse of vocal sounds to communicate.
spermThe male gamete or sex cell that contains the genetic information to be transmitted by the male. Also called spermatozoon.
sperm/osperm cells
sperma-sperm, seed
spermatidsImmature sperm cells developed in the testicle.
spermatozoaMature male germ cells derived from spermatids.
SPFskin protection factor
sphen/owedge, wedge-shaped
sphenoid boneAn irregular unpaired bone situated at the skull base and wedged between the frontal, temporal, and occipital bones.
sphenoid/osphenoid (compound bone at base of skull)
spher/osphere, round
spherocytesSmall, abnormal spherical red blood cells with more than the normal amount of hemoglobin.
spherocytosisA blood disorder characterized by the presence of small, sphere like red blood cells.
sphincterA ring-link muscle that constrictions a natural body passage or orifice and which relaxes as needed. Present in the rectum and urinary tract.
sphygmomanometerDevice for measuring arterial blood pressure. Includes an inflatable cuff, inflating bulb and a gauge showing the blood pressure.
spicaA figure-eight bandage.
spina bifidaA spinal birth defect.
spinal cordThe section of the central nervous system enclosed in the vertebral column.
spinal nervesThe 31 paired peripheral nerves formed by the union of the dorsal and ventral spinal roots from each spinal cord segment. The spinal nerve plexuses and the spinal roots are also included.
spinal punctureTapping fluid from the subarachnoid space in the lumbar region, usually between the third and fourth lumbar vertebrae.
spinal stenosisNarrowing of the spinal canal.
spineThe spinal or vertebral column.
spir/oto breath
spirometerDevice that measures inhaled or exhaled air volume.
splanchnicPertaining to the viscera.
spleenAn encapsulated lymphatic organ through which venous blood filters.
splenectomySurgical procedure involving either partial or entire removal of the spleen.
splenic arteryThe largest branch of the celiac trunk with distribution to the spleen, pancreas, stomach and greater omentum.
splenitisInflammation of the spleen.
splenomegalyEnlargement of the spleen.
splintAn appliance used to prevent movement of a joint or to fixate displaced or movable parts.
spondyl/overtebra, backbone
spondylitisInflammation of the synovial joints of the backbone.
spondylolisthesisForward displacement of a superior vertebral body over the vertebral body below.
spondylolysisThe degeneration of a vertebra.
spondylosisA degenerative spinal disease that can involve any part of the vertebra, the intervertebral disk, and the surrounding soft tissue.
spor/ospore, seed
sporesThe reproductive elements of lower organisms such as bacteria and fungi.
sprainAn injury caused by tearing of the fibers of a ligament.
sputumMaterial coughed up from the lungs.
squamous cell carcinomaMost squamous cell cancers occur on skin that is regularly exposed to sunlight or other ultraviolet radiation. It is the second most common type of cancer in the United States.
ssa half
SSSsick sinus syndrome
-stabilestable, fixed
staped/ostapes (a middle ear bone)
stapedectomySurgical removal of the stapes.
stapesOne of the three ossicles of the middle ear. It transmits sound vibrations from the incus to the internal ear.
staphylo-bunch of grapes
staphylococciGram-positive bacteria. Natural populations of Staphylococcus are found on the skin and mucous membranes.
staphylococcusAny of various spherical gram-positive parasitic bacteria, causing skin and other infections.
stasisA cessation or diminution of flow of blood or other fluids.
-stasismaintenance of level, prevent increase
-statagent or device for keeping something from changing
STDsexually transmitted disease
steatomaA cyst or tumor of the sebaceous gland.
stem cellsAn unspecialized cell that can give rise to one or more different types of specialized cells, such as blood cells and nerve cells. Stem cells are present in embryos and in various tissues of adult organisms
stenosisThe abnormal narrowing of a passage or opening.
-stenosisabnormal narrowing
stentsA small mesh tube used to treat narrow or weak arteries.
stere/othree dimensional
stereognosisPerception of shape and form of objects by the sense of touch.
sterileUnable to produce offspring.
sterilizationThe destroying of microorganisms by heat, chemicals, irradiation or other means.
stern/osternum (breastbone)
sternoclavicular jointA double gliding joint formed by the clavicle, superior and lateral parts of the manubrium sternum at the clavicular notch and the cartilage of the first rib.
sternumA long, narrow, and flat bone commonly known as breastbone occurring in the midsection of the anterior thoracic segment or chest region, which stabilizes the rib cage and serves as the point of origin for several muscles that move the arms, head and neck.
steroidsA hormone produced by the body. Also a drug used for treating swelling or to (illegally) improve athletic performance.
stethoscopeInstrument for listening to body sounds (auscultation).
STHsomatotropic hormone
stomachA saclike digestive organ situated in the left upper quadrant of the abdomen between the termination of the esophagus and the beginning of the duodenum.
stomach ulcerUlceration of the gastric mucosa due to contact with gastric juice.
stomatitisInflammation of the soft tissues of the mouth. Canker sores are an example.
-stomynew opening
stoolFeces discharged from the anus.
strabismusA condition that causes crossed eyes.
strainOverstretching or overexertion of a part of the musculature.
stressThe unfavorable effect of environmental factors on the physiological functions.
stress testA test to evaluate heart function by monitoring heart rate, breathing, blood pressure and EKG while the patient exercises with a treadmill or exercise bike.
stridorA very loud, wheezing breath sound heard when the trachea or larynx is obstructed.
strokeA group of pathological conditions characterized by sudden, non-convulsive loss of neurological function due to brain ischemia or intracranial hemorrhages. It is both common and deadly.
stroke volumeThe amount of blood pumped out of one ventricle of the heart in one beat.
-stromaconnective or supportive tissue of an organ
stromalRelating to the foundation-supporting tissues of an organ.
stuporA state of diminished responsiveness to stimuli. The person is still conscious and can make voluntary movements.
stutteringA disturbance in the normal fluency characterized by frequent repetitions, pauses or prolongations of syllables.
styeAcute bacterial inflammation of a gland at the base of an eyelash.
sub-under, below
subclavianBelow the clavicle.
subcutaneousBeneath the skin.
subduralBelow the dura mater.
subdural effusionLeakage and accumulation of cerebrospinal fluid in the subdural space which may be associated with an infection, craniocerebral trauma, brain neoplasms, intracranial hypotension and other conditions.
sublimationA defense mechanism through which unacceptable impulses are diverted into socially acceptable channels.
sublingualBelow the tongue.
sublingual glandA salivary gland located under the tongue in the floor of the oral cavity.
subretinal fluidAn exudate between the retina and choroid from various sources including the vitreous cavity, subarachnoid space or abnormal vessels.
subtalar jointFormed by the articulation of the talus with the calcaneus.
sucroseCane or beet sugar.
suctionThe removal of secretions, gas or fluid from hollow or tubular organs or cavities by means of a tube and a device that acts on negative pressure.
sudden cardiac arrestA sudden and unexpected cessation of cardiac function due to electrical malfunction. Reversible if immediately treated.
sudden cardiac deathSudden, unexpected death caused by loss of cardiac function.
sudden infant death syndromeThe abrupt and unexplained death of an apparently healthy infant under one year of age. Positioning infants for sleep on their backs or sides has reduced SIDS incidence.
sunburnAn injury to the skin due to excessive sun exposure, causing erythema, tenderness, and sometimes blistering.
sunstrokeHeat stroke caused by exposure to the sun. It is characterized by dangerously high body temperature, red skin, delusions, convulsions or coma. It can be a life-threatening emergency and is most common in infants and the elderly.
super-above, beyond
superegoThe component of the personality associated with ethics, standards, and self-criticism.
superficialnear the surface
supinationThe condition of being supine. Alternatively, the act of turning the hand so that the palm is up.
supinelying face up
suppositoryMedicated dosage that is designed to be inserted into the rectal, vaginal, or urethral orifice of the body for absorption.
suppurationA pathologic process consisting in the formation of pus.
supra-above, upward
supraglottitisInflammation of the of the laryngeal tissue above the glottis, particularly the epiglottis.
sural nerveA branch of the tibial nerve which supplies sensory innervation to parts of the lower leg and foot.
surface tensionThe force acting on the surface of a liquid, tending to minimize the area of the surface.
susceptibilityVulnerable to a disease.
suspensionA preparation of an undissolved substance dispersed in a liquid.
suturesA stitch or stitches used to close a wound.
SVTsupraventricular tachycardia
sycosisInflammation of hair follicles.
symbiosisA Relationship between different species where both of the organisms in question benefit from the presence of the other.
symptomSubjective evidence of disease. For example, a patient's complaints.
synaps/opoint of contact
synapseThe junctional area between two connected nerves or between a nerve and the effector organ.
syncopeFainting. Loss of consciousness due to diminished blood flow to the brain.
syndactylyA congenital anomaly of the hand or foot, marked by the webbing between adjacent fingers or toes.
syndromeA characteristic set of signs and symptoms of a particular disorder.
synovectomyRemoval of part or all of the synovial membrane of a joint
synovi/osynovial membrane, synovial joint
synovitisInflammation of a synovial membrane.
syphilisA sexually transmitted disease. A bacterial infection.
syring/otube, pipe, fistula
syringeAn instrument used for injecting or withdrawing fluids.
systemicAffecting the body as a whole.
systemic circulationThe circulation of the blood to all parts of the body except the lungs.
systemic lupus erythematosusAn autoimmune disease in which the immune system mistakenly attacks healthy tissue.
systolePeriod of heart contraction when blood is surging from the heart into the systemic circulatory system and the lungs.
systolic blood pressureArterial blood pressure during heart contraction. In blood pressure readings, it is the first number.
systolic murmursHeart murmurs which occur during systole. They are heard between the first and the second heart sounds.

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