Glossary - All

Displaying glossary terms: 1701 - 1750 of 2011 in total
side effect
An unwanted, and sometimes dangerous, reaction caused by medication or other treatment.
sigmoid colon
Section of the colon leading to the rectum that makes an S-shaped curve.
Internal examination of the rectum and sigmoid colon using a flexible viewing tube inserted through the anus.
signature strengths
Character strengths such as curiosity, integrity, and modesty that people identify with, appreciate having, and enjoy using.
sildenafil citrate
The active ingredient in Viagra. It blocks the breakdown of cyclic guanosine monophosphate, a chemical necessary for an erection.
silent heart attack
Heart attack that occurs without pain or symptoms; occurs most commonly in the elderly or in people with diabetes.
silent ischemia
Shortage of oxygen delivery to the heart muscle that causes no symptoms.
single-photon absorptiometry
A test using gamma rays to measure bone density, usually in the forearm.
sinoatrial node
The natural pacemaker of the heart. Located in the right atrium, the sinoatrial node, sometimes called the sinus node, initiates the heart's electrical activity.
sinus node
A specialized group of heart cells in the right atrium that generate the electrical impulses that cause the heart muscle to contract; also called the heart's natural pacemaker.
sinus rhythm
The heart's normal rate and rhythm.
skeletal muscles
Muscles attached to bones throughout the body that allow voluntary movement to occur.
skin resurfacing
Any of several approaches to improve skin texture, tone, wrinkle appearance, and discolorations by promoting new collagen and epidermal growth. Chemical peels, dermabrasion, microdermabrasion, and laser procedures are skin-resurfacing techniques.
sleep apnea
Temporary pause in breathing during sleep, lasting at least 10 seconds and associated with a fall in blood oxygen or arousal from sleep. Obstructive sleep apnea is caused by an obstruction in the airway blocking air flow; central sleep apnea occurs when the brain temporarily stops sending signals to the muscles that control breathing.
sleep architecture
The pattern made when sleep stages are charted on a hypnogram.
sleep paralysis
A feeling of paralysis that may occur during the transition between wakefulness and sleep if the REM sleep stage begins before a person is fully asleep; classically associated with narcolepsy.
sleep spindles
On an electroencephalogram (EEG), brief rhythmic bursts of activity that appear during stage 2 sleep.
A slender piece of material surgically inserted under the urethra or bladder neck to provide support and improve continence.
slipped disk
See herniated disk.
slipped vertebra
Forward displacement of a vertebra in relation to the vertebra immediately below; also called spondylolisthesis.
slit lamp
An instrument that magnifies internal structures of the eye with the aid of a thin beam of light. Also called a biomicroscope.
slow-twitch fiber
One of two main types of skeletal muscle fibers. Slow-twitch fibers are recruited most heavily for endurance (aerobic) exercises. See also fast-twitch fiber.
slow-wave sleep
Sleep stages 3 and 4; during slow-wave sleep the brain becomes less responsive to external stimuli.
small intestine
A section of the digestive system that includes the duodenum, jejunum, and ileum and plays the major role in absorbing nutrients for the body.
An acronym for an approach to setting goals for behavioral change: set a very Specific goal; find a way to Measure progress; make sure it's Achievable; make sure it's Realistic; and set Time commitments.
Snellen chart
The conventional eye chart used to test vision with lines of block letters in progressively smaller sizes.
Bodily symptoms that have no clear physical cause or are out of proportion to a given ailment, and may stem from psychological causes.
Talking in one's sleep.
A crystalline alcohol used as a sweetening agent.
A hollow chamber into which inhaled medicines can be squirted before inhalation. Spacers 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.
An involuntary muscle contraction.
A ring of muscle that surrounds an opening and can be contracted to close the opening. For example, the muscles found at the anus and the opening of the bladder are sphincters.
A device for measuring blood pressure.
spina bifida
A congenital defect in which part of the spinal column fails to develop completely, leaving part of the spinal cord exposed.
spinal fusion
A procedure to attach 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.
spinal tap
Use of a hollow needle to withdraw fluid from the lower part of the spinal canal for testing. Also called a lumbar puncture.
spinous process
The lever-like backward projection extending off each vertebra, to which muscles and ligaments are attached.
A device that measures airway obstruction, used to diagnose asthma and determine the severity of the condition.
A simple, painless breathing test performed in a physician's office or pulmonary function laboratory that measures how fast air can be forced from the lungs and the total amount of air that can be emptied from the lungs.
splenic flexure syndrome
A painful spasm in the left upper abdomen below the rib cage, produced by areas of trapped gas in the colon.
Forward displacement of a vertebra in relation to the vertebra immediately below.
A general term for degeneration of the spine that causes narrowing of the spinal canal and the small openings (intervertebral foramina) through which spinal nerves exit the canal.
spongy bone
Porous bone, also called trabecular bone, often found at the center of long bones.
A stretched or torn ligament.
A mixture of saliva and mucus that is coughed up from the respiratory tract. Sputum may be examined in a laboratory for signs of disease.
squamous cell
Flat, scaly epithelial cell.
stable angina
Angina pectoris (chest pain with exertion or stress) that is well-controlled with medicines and lifestyle changes.
stable coronary artery disease
Narrowings in the heart arteries that cause angina pectoris in a predictable and stable pattern over time (for example, after walking a certain distance).