Dictionary

Body systems

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

SA nodeSinoatrial node: a small cluster of cells in the right atrium that starts each heartbeat.

sacralHaving to do with the sacrum, the triangle-shaped bone at the base of the spine between the hip bones.

sacrumThe large, triangle-shaped bone at the base of the spine, between the two hip bones.

salivaThe clear, watery fluid made by glands in the mouth that keeps it moist and begins digestion.

salivaryRelating to saliva, the watery fluid in the mouth, or to the glands that make it.

salivary glandA gland that makes saliva and releases it into the mouth.

sarcomaA cancer that starts in bone or in the body's soft tissues, such as muscle, fat or blood vessels.

SARSSevere acute respiratory syndrome: a lung infection caused by a coronavirus, first seen in 2002–2003.

saturated fatA type of fat that is usually solid at room temperature, found mostly in animal foods and some tropical oils.

saturationHow full something is; in nursing, usually the percentage of hemoglobin in the blood that is carrying oxygen.

SBPAn abbreviation that most often means systolic blood pressure, and sometimes spontaneous bacterial peritonitis.

scabA dry, hard crust of dried blood and fluid that forms over a healing wound.

scabiesA skin infestation by tiny mites that burrow into the top layer of the skin.

scalpThe skin and tissue that cover the top of the head, where the hair grows.

scapulaThe flat, triangle-shaped bone at the back of each shoulder; the shoulder blade.

scarTough, fibrous tissue that replaces normal skin or tissue after an injury has healed.

scarlet feverAn infection with group A strep bacteria in which a toxin made by the bacteria causes a red rash over the body.

schizophreniaA long-term mental illness that changes a person's thinking, feelings and behavior, often with a loss of contact with reality.

SCIDSevere combined immunodeficiency: a group of rare inherited disorders in which the immune system barely works from birth.

scleraThe tough white outer layer of the eyeball.

sclerosisAbnormal hardening of a body tissue, often from scarring.

scoliosisA sideways curve of the spine.

scrotumThe pouch of skin and muscle that holds the testicles.

sebaceous glandA small gland in the skin that releases an oil (sebum) into the hair follicles to keep skin and hair soft.

seborrheic dermatitisA common, long-lasting inflammation of the skin in oily areas such as the scalp, face and chest.

secretionA substance a gland or cell makes and releases, such as mucus, saliva, sweat or a hormone.

seizureA sudden burst of abnormal electrical activity in the brain that changes movement, feeling, behavior or awareness.

self-conceptThe picture a person has of who they are, including their abilities, roles, body and worth.

self-esteemHow much a person values and respects themselves.

self-harmHurting one's own body on purpose, such as by cutting, burning or hitting oneself.

sensationThe ability to feel touch, pain, temperature, position or other input through the senses, or a feeling itself.

sensoryRelating to the senses, or to the nerves that carry feeling from the body to the brain.

sensory impairmentA loss or weakening of one or more senses, such as sight, hearing, touch, taste or smell.

sensory nerveA nerve that carries signals about touch, pain, temperature, position and the other senses toward the brain and spinal cord.

separation anxietyFear and distress that a young child shows when separated from a parent or main caregiver.

sepsisA severe whole-body response to an infection that damages the body's own organs.

septic shockThe most severe stage of sepsis, in which the circulation fails and blood pressure stays low even after IV fluids.

septumA wall of tissue that divides two spaces or cavities, such as the two sides of the heart or nose.

serosanguineousDescribes drainage that is thin and watery with a little blood in it, so it looks pale pink.

serotoninA chemical messenger in the brain, gut and blood that helps control mood, sleep, appetite and other functions.

serotonin syndromeA drug reaction caused by too much serotonin activity in the nervous system.

serousThin, watery and clear to pale yellow, like the fluid part of blood.

severe allergic reactionAn allergic reaction strong enough to affect breathing, circulation or several body systems at once, not just the skin.

sexual abuseAny sexual act forced on a person, or done with someone who cannot agree to it, such as a child.

sexual intercourseSexual activity in which the penis enters the vagina; the term is also used for anal and oral sex.

sexually transmitted infectionAn infection passed from one person to another mainly through sexual contact.

sheathA covering that wraps around a structure; in procedures, a short hollow tube left in a blood vessel to pass catheters through.

shockA life-threatening state in which blood flow is too low to bring enough oxygen to the body's tissues.

shortness of breathThe feeling of not getting enough air or of having to work hard to breathe.

shuntA passage that moves blood or other fluid from one place to another, either made by a surgeon or present in the body.