Dictionary

Body systems

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

syndrome of inappropriate antidiuretic hormoneA condition in which the body releases more antidiuretic hormone than it needs, so the kidneys hold on to too much water.

synovial fluidThe thick, slippery fluid inside movable joints that lets the bones move smoothly.

synovial jointA freely movable joint in which the bone ends sit in a capsule filled with lubricating fluid.

synthesizeTo make something by combining simpler parts, or to combine pieces of information into a whole.

syphilisA bacterial infection, spread mainly through sex, caused by Treponema pallidum.

systemicAffecting the whole body rather than one part.

systemic vascular resistanceThe resistance to blood flow in the body's arteries that the left ventricle has to push against.

systemic veinA vein of the body's main circulation, carrying blood from the tissues back toward the right side of the heart.

systoleThe part of each heartbeat when the heart muscle squeezes and pumps blood out.

systolic pressureThe top number in a blood pressure reading: the pressure in the arteries while the heart pumps.

T waveThe wave on an electrocardiogram that shows the heart's lower chambers recovering electrically after each beat.

tachycardiaA heart rate faster than normal; in an adult, more than 100 beats per minute.

tachypneaA breathing rate faster than normal, above 20 breaths per minute in an adult.

tardive dyskinesiaA movement disorder with repeated movements a person cannot control, most often of the face, lips and tongue.

Tay-Sachs diseaseAn inherited disease in which a missing enzyme lets a fatty substance build up and destroy nerve cells in the brain and spinal cord.

TBSATotal body surface area: the whole skin surface of the body, used to describe how much of it a burn covers.

telemetryContinuous heart rhythm monitoring in which a small device worn by the client sends the ECG signal to a central screen.

temporal lobeThe part of each side of the brain, above the ear, that handles hearing, memory and understanding language.

tendonA tough cord of tissue that attaches a muscle to a bone.

tension pneumothoraxA collapsed lung in which air keeps building up in the chest under pressure and presses on the heart and the other lung.

teratogenAnything a pregnant person is exposed to that can cause birth defects in the developing baby.

testisOne of the two male glands in the scrotum that make sperm and the hormone testosterone; plural testes.

testosteroneThe main male sex hormone, made mostly in the testes and in small amounts by the ovaries and adrenal glands.

tetanusA serious illness caused by a nerve toxin made by the bacterium Clostridium tetani.

tetanyInvoluntary muscle cramps and spasms that come from nerves firing too easily.

tetralogy of FallotA congenital heart defect made up of four problems in the structure of the heart.

thalamusA pair of egg-shaped masses deep in the brain that relay sensory signals to the cerebral cortex.

thalassemiaAn inherited blood disorder in which the body makes too little normal hemoglobin.

thermoregulationThe body's control of its own temperature, keeping it within a narrow normal range.

thighThe part of the leg between the hip and the knee.

third trimesterThe last part of pregnancy, from week 28 until birth.

thoracicRelating to the chest, or to the middle part of the spine.

thoraxThe chest: the part of the body between the neck and the abdomen.

thrillA buzzing or vibrating feeling felt with the fingertips over a blood vessel or the heart.

thrombinAn enzyme in the blood that turns fibrinogen into fibrin, the threads that hold a blood clot together.

thrombocytopeniaA blood platelet count below normal, under 150,000/mm3.

thromboembolismA blockage of a blood vessel by a blood clot that formed in one place and traveled through the blood to another.

thrombosisThe forming of a blood clot (a thrombus) inside a blood vessel or the heart.

thymusA small gland in the upper chest, behind the breastbone, where T cells (a kind of white blood cell) mature.

thyroidRelating to the thyroid gland in the neck or the hormones it makes; often used alone to mean the gland itself.

thyroid glandA butterfly-shaped gland at the front of the neck that makes hormones that control the body's metabolism.

thyroid hormoneA hormone made by the thyroid gland that controls how fast the body uses energy.

thyroidectomySurgery to remove all or part of the thyroid gland in the neck.

tibiaThe large inner bone of the lower leg, between the knee and the ankle; the shinbone.

tidal volumeThe amount of air moved in or out of the lungs with one normal breath.

tineaA fungal infection of the skin, hair or nails.

tinea capitisA fungal infection of the scalp and hair, also called ringworm of the scalp.

tinea corporisA fungal infection of the skin of the body, commonly called ringworm, although no worm is involved.

tinea crurisA fungal infection of the skin of the groin and inner thighs, often called jock itch.

tinea pedisA fungal infection of the skin of the feet, often called athlete's foot.