Dictionary

Body systems

Anatomy and the conditions of each body system, from the heart and lungs to the skin.

sprainA stretch or tear of a ligament, the tough band that holds bones together at a joint.

sputumMucus and other material coughed up from the lungs and lower airways.

squamous cell carcinomaA cancer that starts in squamous cells, the thin, flat cells of the skin's outer layer and the linings of some organs.

stagingWorking out how large a cancer is and how far it has spread in the body.

stasisA slowing or stopping of the normal flow of a body fluid.

stem cellAn unspecialized cell that can divide to make more of itself and develop into specialized cells.

STEMIST-elevation myocardial infarction: a heart attack in which the ECG shows a raised ST segment.

stenosisNarrowing of a passage or opening in the body, such as a blood vessel, heart valve or the spinal canal.

sternumThe breastbone: the flat bone in the middle of the front of the chest.

steroidA fat-based chemical built from cholesterol; the group includes hormones such as cortisol and estrogen, and many drugs.

Stevens-Johnson syndromeA rare, severe reaction, most often to a drug, in which the skin and the moist linings of the body blister and peel away.

stillbirthThe death of a fetus in the uterus at 20 weeks of pregnancy or later.

stimulationSomething that rouses a nerve, organ or person to act or respond, or the act of rousing it.

stoolSolid waste passed from the bowel through the anus; also called feces.

stranger anxietyFear and distress an infant shows around people they do not know.

StreptococcusA group of round bacteria that grow in chains, some of which cause infections in people.

stress managementWays of reducing stress or coping with it in healthy ways.

strictureA narrowed section of a hollow body passage, such as the urethra, esophagus or bowel, that is tighter than normal.

stridorA high-pitched, harsh sound made while breathing, usually heard when breathing in.

strokeSudden damage to part of the brain because its blood supply is blocked or a blood vessel in it bursts.

stroke volumeThe amount of blood the left ventricle pumps out with each heartbeat.

subarachnoid hemorrhageBleeding into the fluid-filled space between the two inner layers of tissue that cover the brain.

subarachnoid spaceThe space between two of the thin membranes that cover the brain and spinal cord, filled with cerebrospinal fluid.

subcostalBelow the ribs.

subcutaneous tissueThe layer of fat and loose connective tissue under the skin that attaches the skin to muscle.

subduralLocated beneath the dura, the tough outer membrane covering the brain and spinal cord.

subdural hematomaA collection of blood between the brain's tough outer covering (the dura) and the brain.

substanceIn mental health and addiction, a drug or chemical that changes mood, thinking or behavior, such as alcohol, nicotine or opioids.

substance abuseAn older term for using alcohol or drugs in a harmful way; today it is usually called substance use disorder.

substance misuseUsing alcohol, drugs or medicines in a way that can cause harm, or using a medicine other than as prescribed.

substance useThe use of alcohol, tobacco, drugs or medicines not as prescribed; when it causes harm, it is called substance use disorder.

substance use disorderA condition in which a person keeps using alcohol or another drug even though it is causing them harm.

suctioningRemoving mucus, saliva or other secretions from the mouth, nose or airway with a tube connected to a suction source.

sudden infant death syndromeThe sudden, unexplained death of a baby under 1 year old, usually during sleep, where no cause is found after full investigation.

sunburnSkin damage and inflammation from too much ultraviolet (UV) light from the sun or a tanning bed.

superficialNear or on the surface of the body or of a structure.

superior vena cavaThe large vein that carries blood from the head, neck, arms and upper chest back to the right atrium of the heart.

supinationTurning the forearm so the palm faces up or forward; for the foot, rolling it so the weight is on the outer edge.

supplementationAdding something to the diet, such as a vitamin, mineral or extra food, to meet the body's needs.

supraventricular tachycardiaA fast, regular heart rhythm that starts above the ventricles, usually 150 to 250 beats a minute.

surfactantA fatty substance coating the inside of the lungs' air sacs that lowers surface tension so they stay open.

swallowTo move food, liquid or saliva from the mouth down the throat into the esophagus.

swallowingMoving food, liquid or saliva from the mouth through the throat and esophagus to the stomach.

sympathetic nervous systemThe branch of the autonomic nervous system that gets the body ready for stress or danger ("fight or flight").

symphysisA joint where two bones are joined firmly by a pad of cartilage that allows only a little movement.

symphysis pubisThe joint at the front of the pelvis where the left and right pubic bones meet.

synapseThe tiny gap where a nerve cell passes a signal to another nerve cell, a muscle or a gland.

syncopeFainting: a short loss of consciousness from a drop in blood flow to the brain.

syncytialRelating to a syncytium, a large cell-like mass with many nuclei formed when cells fuse together.

syndromeA group of signs and symptoms that tend to occur together and make up a recognized condition.