Glossary

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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Saccharides	a group of carbohydrates, including sugars and starches
Sacroiliac joints	the pair of joints located in the pelvis between the sacrum and the hipbones
Sacroiliitis	inflammation of the sacroiliac joints, which causes pain in the lower body
Sacrum	the triangular bone located at the bottom of the spine that is connected to the tailbone, the hipbones near the sacroilial joints, and the rest of the spine
SADS	see Seasonal affective disorder syndrome
Safe sex	measures taken to reduce the risk of acquiring a sexually transmitted disease, such as the use of a condom
Saline	a salt solution or any substance that contains salt
Salivary glands	a group of glands that secrete saliva into the mouth
Salmonella	a group of bacteria; includes a species that causes food poisoning and another responsible for typhoid fever
Salmonellosis	infection by salmonella bacteria
Salpingectomy	surgical removal of one or both fallopian tubes
Salpingitis	inflammation of a fallopian tube
Salpingography	X-ray examination of the fallopian tubes
Salpingolysis	removal of abnormal scar tissue between a fallopian tube and nearby tissue
Salpingo-oophorectomy	the surgical removal of one or both of the fallopian tubes and one or both of the ovaries
Salpingostomy	surgical opening of a fallopian tube for drainage or removal of an obstruction
Sarcoidosis	a rare disease with no known cause that leads to inflammation in tissues throughout the body, including the lymph nodes, lungs, liver, skin, and eyes
Sarcoma	a cancer in connective tissue, fibrous tissue, or blood vessels
Saturated fat	fats that contain the maximum amount of hydrogen possible, such as those found in meats and dairy products; can contribute to coronary heart disease and the development of some cancers
Saturday night palsy	temporary paralysis of the arm after extended pressure on a nerve in the armpit
Scabies	a highly contagious skin disorder caused by a mite that burrows into the skin and produces an intense, itchy rash
Scarlet fever	an infectious childhood disease, caused by a streptococcus bacteria, that leads to a sore throat, fever, and rash
Schistosomiasis	infestation by a parasitic blood worm that can damage the liver, bladder, and intestines
Schizophrenia	a group of mental disorders characterized by abnormal thoughts, moods, and actions; sufferers have a distorted sense of reality, and a split personality (thoughts do not logically fit together)
Schsnlein-Henoch purpura	inflammation and leakage of blood vessels, causing a rash
Sciatica	pain along the sciatic nerve, which runs down the length of the leg to the foot; usually caused by pressure on the nerve due to disk prolapse or a tumor, abscess, or blood clot
Sclera	the tough, white coating that covers and protects the inner structures of the eye
Scleroderma	an immune system disorder of varying degree that can affect many areas of the body
Sclerotherapy	treatment of varicose veins by injection of a solution that destroys them
Scoliosis	a condition in which the spine curves to one side and usually curves toward the opposite side in another section to compensate, producing a characteristic S shape
Screening	the testing of an otherwise healthy person in order to diagnose disorders at an early stage
Scrotum	the sac containing the testicles
Scurvy	a disease caused by a lack of vitamin C, characterized by weakness, bleeding and pain in joints and muscles, bleeding gums, and abnormal bone and tooth growth
Seasonal affective disorder syndrome	a type of depression that seems to be linked to shorter periods of daylight during the fall and winter
Sebaceous cyst	a swelling that occurs under the skin, most commonly on the scalp, face, ears, and genitals; although usually harmless, can grow very large and become painful if infected
Seborrhea	excessive oiliness of the face and scalp
Sebum	the oily, lubricating substance that is secreted by glands in the skin
Secondary	describes a disease or disorder that follows or is caused by another one
Sedatives	a group of drugs that have a calming effect; used to treat anxiety and pain, bring on sleep, and help relax a person before surgery
Seizure	sudden uncontrolled waves of electrical activity in the brain, causing involuntary movement or loss of consciousness
Selenium	an element needed by the body only in very small amounts that helps maintain tissue elasticity
Semen	fluid released during ejaculation that contains sperm along with fluids produced by the prostate gland and the seminal vesicles
Semen analysis	a procedure in which a semen sample is examined to determine the amount of sperm present, along with their shape and ability to move; commonly used in the treatment of male infertility
Seminal vesicles	two saclike glands in men that produce part of the fluid in semen
Seminiferous tubules	coiled tubes inside of the testicle that are the site of sperm production
Seminoma	a type of testicular cancer that is made up of only a single type of cell
Senile plaques	abnormal deposits of a protein called amyloid in the brain; characteristic of Alzheimer disease
Sensorineural hearing loss	deafness caused by damage to the inner ear or the nerve that conducts signals from the ear to the brain
Sensory nerve	nerves that carry information about the body's senses toward the brain
Sensory organ	an organ that receives and relays information about the body's senses to the brain
Sepsis	the infection of a wound or tissue with bacteria, causing the spread of the bacteria into the bloodstream; now also known as systemic inflammatory response syndrome caused by a microbe
Septal defect	a birth defect in which a hole is present in the wall that separates the left and right sides of the heart
Septic arthritis	joint inflammation caused by a bacterial infection
Septicemia	a life-threatening condition in which bacteria multiply in the blood and produce toxic materials; commonly known as blood poisoning; now also known as systemic inflammatory response syndrome.
Septic shock	a life-threatening condition in which tissues become damaged and blood pressure drops due to bacteria multiplying and producing poisons in the blood
Serotonin	a chemical that transmits nerve impulses in the brain, causes blood vessels to constrict (narrow) at sites of bleeding, and stimulates smooth muscle movement in the intestines
Serum	the clear, watery fluid that separates from clotted blood
Sex chromosomes	the X and Y chromosomes that determine a person's gender; women normally have two X chromosomes and men normally have one X and one Y
Sex hormones	hormones responsible for producing sex characteristics and controlling sexual functions
Sex-linked disorder	a disorder that is caused by genes located on the sex chromosomes
Sexually transmitted disease	infections that are most commonly spread through sexual intercourse or genital contact
Shigellosis	a bacterial infection of the intestines, causing abdominal pain and diarrhea
Shingles	a nerve infection caused by the chickenpox virus, causing areas of painful rash covered with blisters
Shin splints	pain and tenderness experienced in the lower leg as a result of damage or strain to leg muscles and tendons; usually caused by exercise
Shock	a reduced flow of blood throughout the body, usually caused by severe bleeding or a weak heart; without treatment, can lead to a collapse, coma, and death
Shunt	an artificially constructed or an abnormal passage connecting two usually separate structures in the body
Sickle cell anemia	a genetic disorder in which the red blood cells are abnormal and deformed, causing anemia (reduced ability to transport oxygen in the blood) and clogging of blood vessels; bouts of fever, headache, and weakness result
Sickle cell trait	a less serious form of sickle cell anemia
Sick sinus syndrome	abnormal functioning of the structure that regulates the heartbeat, causing episodes of abnormal heart rhythm
SIDS	see Sudden infant death syndrome
Sigmoidoscopy	an examination of the rectum and the lowest part of the large intestine using a flexible viewing tube inserted through the anus
Silicone	a group of compounds of silicon and oxygen; commonly used as implants in cosmetic surgery because they resist body fluids and are not rejected by the body
Silicosis	a respiratory disease caused by inhalation of dust containing the mineral silica
Single photon emission computed tomography	an imaging technique in which a radioactive substance is introduced into the body and the radiation emitted by the substance is detected by a camera and is transformed into cross-sectional images by a computer
Sinoatrial node	the structure that regulates the heartbeat; a natural "pacemaker"
Sinus	a cavity within bone or a channel that contains blood; also refers to an abnormal tract in the body
Sinus bradycardia	a regular heart rate of less than 60 beats per minute
Sinusitis	inflammation of the lining of the cavities in the bone surrounding the nose (the sinuses), usually as a result of a bacterial infection spreading from the nose
Sinus rhythm	normal heart rhythm
Sinus tachycardia	a regular heart rate of over 100 beats per minute
Sjsgren's syndrome	a condition characterized by dryness of the eyes, mouth, and vagina that tends to occur along with certain disorders of the immune system
Skin graft	a method of treating damaged or lost skin in which a piece of skin is taken from another area of the body and transplanted in a damaged or missing section
Skin patch	a sticky patch attached to the surface of the skin that releases drugs into the bloodstream
Skin patch test	a diagnostic test in which different allergens are taped to the skin to determine which causes an allergic reaction
Skin prick test	a test performed to determine a person's sensitivity to a certain allergen by applying it to a small needle and using that needle to pierce the skin
Skull	the bones that form the framework of the head and enclose and protect the brain and other sensory organs
Sleep apnea	a condition in which breathing stops for very short periods of time during sleep
Sleeping sickness	an infectious disease in Africa spread by the bite of a tsetse fly that causes a fever and weakness
Slipped disk	the common term for disk prolapse
Small-cell carcinoma	the most serious form of lung cancer
Small intestine	the long tube running from the stomach to the large intestine that is involved in digestion of foods and absorption of nutrients
Smallpox	a highly contagious and often fatal viral infection that has been completely eradicated by immunization
Smear	a sample of cells spread across a glass slide to be examined through a microscope
Sodium	a mineral that plays a role in the body's water balance, heart rhythm, nerve impulses, and muscle contraction; present in table salt (sodium chloride)
Sodium bicarbonate	a substance used as an antacid
Solar plexus	the largest network of nerves in the body, located behind the stomach
Somatic	pertaining to the body
Spasm	an involuntary muscle contraction; can sometimes be powerful and painful
Spasticity	muscle stiffness caused by an increase in contractions of the muscle fibers
Spastic paralysis	spasticity involving partial paralysis
SPECT	see Single photon emission computed tomography
Speculum	an instrument that holds an opening of the body open so that an examination can be performed or a sample can be taken
Speech therapy	treatment to help someone overcome a problem communicating verbally
Sperm	the male sex cell produced in the testicles
Sperm antibody	an antibody against sperm that can be produced by a woman's immune system
Spermatocele	a harmless cyst containing fluid and sperm that occurs in the tube through which sperm travel from the testicles
Sperm count	the amount of normally functioning sperm per some unit of semen; used to determine a man's fertility
Spermicide	a contraceptive substance that kills sperm
Sphincter	a ring of muscle fibers located around a naturally occurring passage or opening in the body that opens and closes to regulate passage of substances
Sphygmomanometer	an instrument used to measure blood pressure
Spider nevus	a collection of dilated (widened) capillaries on the skin that creates a patch resembling a spider
Spina bifida	a birth defect in which a section of the baby's spine fails to develop completely, leaving the spinal cord exposed in that section
Spina bifida occulta	the least dangerous form of spina bifida, in which bones in the spine fail to close but there is no protrusion of the spinal cord or its fluid cushion out of the body
Spinal cord	a long tube of nerve tissue inside the spinal column, running from the brain down the length of the back inside of the spine
Spinal fusion	the surgical joining of two or more adjacent vertebrae using bone fragments; used to help severe back pain or prevent damage to the spinal cord
Spinal tap	another term for a lumbar puncture
Spine	the column of bones and cartilage running along the midline of the back that surrounds and protects the spinal cord and supports the head
Spiral fracture	a coiled break in a bone, resembling a corkscrew
Spirometry	a test of lung condition; a person breathes into a machine called a spirometer that measures the volume of air exhaled
Spleen	an organ located in the upper left abdomen behind the ribs that removes and destroys old red blood cells and helps fight infection
Splenectomy	surgical removal of the spleen
Splint	a device that is used to immobilize a part of the body
Splinter hemorrhage	a splinter-shaped area of bleeding under a fingernail or toenail
Spondylitis	inflammation of the joints between the bones of the spine
Spondylolisthesis	the slipping of a vertebra in the spine over the one below it
Spondylolysis	a disorder in which the lower part of the spine is weakened by an abnormally soft vertebra
Sporotrichosis	an infection with a fungus acquired through a skin wound; causes an ulcer at the site of infection and small, rounded masses of tissue near it
Sprain	the tearing or stretching of the ligaments in a joint, characterized by pain, swelling, and an inability to move the joint
Sprue	a digestive disorder in which nutrients cannot be properly absorbed from food, causing weakness and loss of weight
Sputum	mucus and other material produced by the lining of the respiratory tract; also called phlegm
Squamous cell carcinoma	a type of skin cancer arising from flat cells of the epithelium; can also affect the lungs, cervix, and esophagus
Stapedectomy	surgical removal of a stapes (a sound-conducting bone in the middle ear) that cannot move to transmit sound; performed to treat hearing loss caused by otosclerosis
Staphylococci	common bacteria that cause skin infections and a number of other disorders
Status asthmaticus	a life-threatening asthma attack requiring immediate treatment
Status epilepticus	a life-threatening succession of epileptic seizures
STD	see Sexually transmitted disease
Stein-Leventhal syndrome	see Polycystic ovary syndrome
Stem cells	cells that give rise to the different types of blood cells
Stenosis	narrowing of a body passageway
Stent	a device used to hold tissues in place, such as to support a skin graft
Stereotaxic surgery	brain surgery done through a small opening in the skull and guided by X-rays or computer-aided imaging techniques
Sterilization	a surgery performed to make a person incapable of reproducing; also refers to the process of killing microorganisms on objects such as surgical instruments
Sternum	the long, flat bone located at the center of the chest
Steroids	a group of drugs that includes corticosteroids, which resemble hormones produced by the adrenal glands, and anabolic steroids, which are similar to the hormones produced by the male sex organs
Stillbirth	a baby that is born dead after the 28th week of pregnancy; also called late fetal death
Stoma	a surgically formed opening on a body surface
Stomach bypass	a surgical procedure to treat an obstructed stomach or severe obesity in which the passage of food is diverted around the stomach and directly into the small intestine
Stomach stapling	a procedure in which the stomach is made smaller by partitioning it off using metal staples; used as an extreme treatment of severe obesity
Stool	another term for feces
Strabismus	a condition in which the eyes are not aligned correctly, such as cross-eye (one eye points inward) and walleye (one eye points outward)
Straight-leg raising	a simple test performed in a doctor's office to check for disk prolapse
Strain	muscle damage resulting from excessive stretching or forceful contraction
Strangulated hernia	a hernia in which the protruding organ or tissue loses its blood supply, requiring emergency surgery
Strawberry nevus	a bright red, raised birthmark that usually disappears without treatment
Strep throat	a throat infection caused by streptococcus bacteria; characterized by a sore throat, fever, and enlarged lymph nodes in the neck
Streptococci	bacteria that cause a variety of diseases, including pneumonia and strep throat
Stress fracture	a bone break resulting from repeated pressure on the bone
Stretch marks	lines on the skin that occur when the inner skin layer is stretched thin and loses its elasticity
Stroke	damage to part of the brain because of a lack of blood supply (due to a blockage in an artery) or the rupturing of a blood vessel; leads to complete or partial loss of function in the area of the body that is controlled by the damaged part of the brain
Stye	a pus-filled abscess in the follicle of an eyelash; caused by a bacterial infection
Subcutaneous	a medical term meaning "beneath the skin"
Submucosa	the layer of connective tissue under a mucous membrane
Suction lipectomy	see Liposuction
Sudden infant death syndrome	the unexpected, sudden death of an apparently healthy baby, the cause of which cannot be found; also called crib death
Suppository	a solid cone or bullet-shaped object made up of a chemically inactive substance and a drug that is inserted into the rectum or vagina; used to administer a drug
Suppuration	the production of pus
Surfactant	a mixture of substances secreted by the air sacs of the lungs that prevents the air sacs from collapsing during exhalation
Surrogate	a woman who agrees to become pregnant and give her baby to someone else when the child is born
Suture	a surgical stitch that helps close an incision or wound so that it can heal properly
Sweat glands	tiny structures in the skin that secrete sweat
Sweat test	a measure of the saltiness of sweat to help diagnose cystic fibrosis
Swimmer's ear	see Otitis externa
Sycosis barbae	a bacterial infection of the hair follicles in the beard area
Sympathetic nervous system	the part of the autonomic nervous system that raises blood pressure and heart rate in response to stress
Syndactyly	a condition in which fingers or toes are fused together
Syndrome	a group of symptoms that indicate a certain disorder when they occur together
Synovectomy	surgical removal of the synovial membrane
Synovial fluid	a lubricating fluid secreted by the synovial membrane
Synovial membrane	the thin membrane that lines the inside of a joint capsule
Synovitus	inflammation of the membrane lining a joint capsule as a result of injury or infection or due to a chronic illness such as rheumatoid arthritis; characterized by redness, swelling, stiffness, and pain
Syphilis	a sexually transmitted disease; initially causes only painless sores on the genitals but can be life-threatening if untreated
Systemic	affecting the whole body
Systemic inflammatory response syndrome	a condition characterized by having two of the following four clinical criteria: fever, rapid breathing, increased heart rate, and abnormal white blood cell count
Systemic lupus erythematosus	a disease of the immune system that causes inflammation of connective tissue in many areas of the body, including the skin, lungs, heart, joints, and kidneys
Systolic pressure	the blood pressure measured while the heart is contracting