Medical Dictionary: S

saturated fat: A fatty acid that’s solid at room temperature and found in animal foods, such as meat, poultry skin, butter, and dairy products. Also found in palm and coconut oils. It raises unhealthy LDL cholesterol levels. In this fatty acid, each molecule carries the maximum number of hydrogen atoms so there are no double bonds between the carbons.

sciatica: Pain along the course of the sciatic nerve (from the buttock, down the back and side of the leg, and into the foot and toes), often because of a herniated disk.

scintillations: The perception of flashing lights or lines that sometimes occurs during the aura of a migraine headache.

sclera: The white of the eye; a tough, protective coating of collagen and elastic tissue that, with the cornea, makes up the outer layer of the eyeball.

scleroderma: An autoimmune disease in which the skin thickens and hardens; sometimes other parts of the body are affected, and joint pain may result.

scotoma: White spots sometimes evident during the aura of a migraine headache.

seasonal affective disorder (SAD): Sadness and depression that’s brought on by a lack of exposure to sunlight. SAD usually appears in the fall or winter and subsides in the spring.

secondary hypertension: High blood pressure that has an identifiable, often correctable, cause.

secondary osteoporosis: Bone loss associated with an identifiable medical condition, treatment with certain drugs, or immobility.

selective estrogen receptor modulators (SERMs): Chemically synthesized drugs that mimic estrogen in some tissues but act to block estrogen’s effects in others.

selective serotonin reuptake inhibitors (SSRIs): Antidepressants that block the reuptake of serotonin into the neurons that released it, leaving more serotonin available to nerve cell receptors.

senescence: The gradual loss of body function over time, which may increase your risk of disease, disability, and death.

sensorineural hearing loss: Permanent hearing loss caused by damage to the cochlea, hair cells, or auditory nerve.

seroma: An accumulation of lymphatic fluid under an incision.

serotonin: A neurotransmitter involved in regulating moods, sleep, and appetite, and inhibiting pain.

serotonin: A neurotransmitter that helps regulate sleep and appetite, mediate moods, and inhibit pain.

sesamoiditis: A painful inflammation in and around two small bones known as sesamoids, located under the head of the first metatarsal.

short-term memory: A memory that lasts anywhere from milliseconds to minutes. It consists of primary memory and working memory.

sigmoid colon: The section of the colon leading to the rectum that makes an S-shaped curve.

sigmoidoscopy: Internal examination of the rectum and sigmoid colon by means of a flexible viewing tube inserted through the anus for the purpose of screening for colorectal cancer.

sleep apnea: Cessation of breathing during sleep, lasting at least 10 seconds and associated with a fall in blood oxygen or arousal from sleep.

sleep architecture: The pattern made when sleep stages are charted on a hypnogram.

sling: A slender piece of material surgically inserted under the urethra or bladder neck to provide support and improve continence.

slipped disk: See herniated disk.

slit lamp: An instrument that magnifies internal structures of the eye with the aid of a slit beam of light. Also called a biomicroscope.

slow-wave sleep: Sleep Stages 3 and 4; during slow-wave sleep the brain becomes less responsive to external stimuli.

somnambulism: Sleepwalking.

somniloquy: Talking in one’s sleep.

spacer: A hollow chamber into which inhaled medicines can be squirted before inhalation. They are used with metered-dose inhalers to help deliver medicine effectively to the bronchial tubes and to reduce the amount of medicine left behind on the tongue and throat.

sphincter: A circular band of muscle that surrounds and is capable of closing off an opening to one of the body’s hollow organs, such as the rectum.

spinal fusion: A procedure to join two or more vertebrae with a bone graft in order to eliminate motion and relieve pain.

spinal stenosis: A narrowing of the spinal canal, which can result in compression of nerve roots.

spinous process: The lever-like backward projection from each vertebra, to which muscles and ligaments are attached.

spirometer: A device that measures airway obstruction, used to diagnose asthma and determine the severity of the condition.

spirometry: A simple, painless breathing test performed in a physician’s office or pulmonary function laboratory that measures how fast you can force air from your lungs and the total amount of air you can empty from your lungs.

spondylolisthesis: Forward displacement of a vertebra in relation to the vertebra immediately below.

spondylosis: A general term for degeneration of the spine that causes narrowing of the spinal canal and the intervertebral foramina through which spinal nerves exit the canal.

sprain: Injury to a ligament that may involve overstretching and the development of small tears.

standardized extract: An herbal product in which a specific concentration of what is thought to be the active constituent meets an established standard of strength.

statins: Cholesterol-lowering medications that interfere with the enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase; also known as HMG-CoA reductase inhibitors. Statins work by changing the way the liver processes lipids.

stent: A wire mesh device inserted into a coronary artery to prop it open once a blockage has been cleared by angioplasty.

steroids: Another term for corticosteroids.

strain: Injury to a muscle, with overstretching or the development of small tears, caused by misuse or overuse.

stress fracture: A hairline crack in a bone that usually occurs from overuse; left untreated, this may lead to displacement of the bones.

stress response: Physiological changes, such as quickened breathing and heartbeat and increased blood pressure, brought on by stress hormones released in response to a real or perceived threat to your safety or ability to cope. Also called the fight-or-flight response.

stress test: A diagnostic test in which cardiovascular measurements — including heart rate, blood pressure, and electrical activity — are recorded while the heart is being “stressed” (usually by having the person exercise on a treadmill or bicycle).

stressors: Stressful events or circumstances that may be real or perceived threats to your equilibrium and well-being.

stroke: A “brain attack”; occurs when a blood vessel supplying the brain becomes obstructed or tears.

subacute thyroiditis: A painful version of conditions caused by viral infections of the thyroid that causes symptoms that may mimic the flu, including fever, muscle aches and pains, and a painful, swollen thyroid gland. Also known as de Quervain’s thyroiditis.

subarachnoid hemorrhage: A hemorrhagic stroke that occurs when a blood vessel on the surface of the brain bursts and bleeds into the space between the brain and the skull; usually caused by an aneurysm or other blood vessel malformation.

subunit vaccines: Vaccines using only part of the antigen to elicit an immune response.

suprachiasmatic nucleus: A small group of nerve cells that controls the sleep/wake cycle; located in the hypothalamus.

sympathetic nervous system: An offshoot of the autonomic nervous system; it cranks up the body when stress hormones are released in response to perceived or real dangers.

synapse: The junction between two neurons, across which chemical neurotransmitters carry messages.

synovectomy: surgical removal of the synovium.

synovial fluid: A thick liquid that lubricates the joints and tendons.

synovial joint: The most mobile type of joint; found in the shoulders, wrists, fingers, hips, etc.

synovitis: Inflammation of the synovium.

synovium: a thin membrane that lines joint capsules and produces synovial fluid.

systolic blood pressure: The first or top number in a blood pressure reading; a measure of the pressure the heart exerts against arterial walls when it contracts to pump blood.