Dictionary

Body systems

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

diarrheaLoose or watery stools, usually three or more times a day or more often than normal for the person.

diastoleThe part of each heartbeat when the heart muscle relaxes and the chambers fill with blood.

diastolicRelating to diastole, the part of each heartbeat when the heart muscle relaxes and its chambers fill with blood.

dietaryHaving to do with the food and drink a person takes in.

diffusionThe movement of particles from an area where they are more concentrated to one where they are less concentrated.

digestionThe process of breaking food down into small parts the body can absorb and use.

digestiveHaving to do with digestion, the breakdown of food into parts the body can absorb.

digestive systemThe organs that take in food, break it down, absorb nutrients and get rid of waste.

dilateTo widen or open up.

dilationThe widening or opening up of a body part, such as the cervix during labor, the pupils or a blood vessel.

diminished breath soundBreath sounds that are quieter or harder to hear than normal when listening to the lungs with a stethoscope.

diphtheriaA serious bacterial infection, caused by Corynebacterium diphtheriae, that mainly affects the nose and throat.

diplopiaSeeing two images of a single object; double vision.

dislocationAn injury in which the ends of bones that meet at a joint are forced out of their normal position.

dissectionA tear in the inner layer of an artery wall that lets blood split the layers apart; also, the cutting apart of tissue in surgery.

disseminated intravascular coagulationA disorder in which clotting is switched on throughout the blood vessels until the clotting factors are used up.

distalFarther from the center of the body or from where a part attaches.

diuresisAn increased output of urine.

diverticulitisInflammation or infection of one or more small pouches that bulge out from the wall of the colon.

diverticulosisA condition in which small pouches bulge outward through weak spots in the wall of the colon.

DNADeoxyribonucleic acid: the molecule in cells that carries the genetic instructions for growth and function.

domestic violenceAbuse by one member of a household or family against another, such as a partner, child or older relative.

dorsalHaving to do with the back of the body, or the top of the hand or foot.

Down syndromeA genetic condition in which a person has a third copy of chromosome 21.

dry skinSkin that lacks moisture and feels rough, flaky or tight; the medical word is xerosis.

Duchenne muscular dystrophyAn inherited disease, mostly in boys, in which a missing muscle protein makes the muscles weaken and waste away over time.

ductA tube in the body that carries fluid from one place to another.

ductus arteriosusA blood vessel in the fetus that connects the pulmonary artery to the aorta, so blood can skip the lungs.

duodenumThe first, short part of the small intestine, just after the stomach.

duraThe tough outer layer of the membranes that cover the brain and spinal cord.

dysarthriaSlurred, slow or hard-to-understand speech because the muscles used to speak are weak or poorly controlled.

dyskinesiaMovements of the body that a person cannot control, such as twisting, jerking or chewing motions.

dysmenorrheaPainful menstrual periods.

dyspareuniaPain during or after sexual intercourse.

dyspepsiaDiscomfort or burning in the upper belly, often with fullness, bloating or nausea after eating.

dysphagiaDifficulty swallowing.

dysphasiaDifficulty speaking or understanding spoken or written language, caused by damage to the brain.

dyspneaDifficult or labored breathing, or the feeling of not getting enough air.

dysrhythmiaA heart rhythm that is not normal: too fast, too slow or irregular.

dystrophyA condition in which a muscle or other tissue weakens and wastes away over time.

dysuriaPain, burning or discomfort when passing urine.

early decelerationA gradual dip in the fetal heart rate that starts, bottoms out and ends at the same times as a uterine contraction.

earwaxThe waxy substance made in the outer ear canal; the medical word is cerumen.

eating disorderA mental illness involving serious problems with eating behavior and with thoughts and feelings about food, weight or body shape.

ecchymosisA bruise: a flat purple or blue patch where blood has leaked from small vessels into the skin.

eclampsiaSeizures in a pregnant or recently pregnant person with preeclampsia, when no other cause explains them.

ectopic pregnancyA pregnancy in which the fertilized egg implants and grows outside the main cavity of the uterus, most often in a fallopian tube.

eczemaA long-lasting skin condition that comes and goes, in which the skin barrier is weak and patches of skin become inflamed; also called atopic dermatitis.

EDDEstimated date of delivery: the expected due date of a pregnancy.

edemaSwelling caused by extra fluid trapped in the body's tissues.