Dictionary

Body systems

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

humerusThe long bone of the upper arm, from the shoulder to the elbow.

Huntington diseaseAn inherited brain disease in which certain nerve cells slowly break down over many years.

hydrationThe amount of water in the body, or the giving of fluids to keep the body's water at a healthy level.

hydrocephalusA buildup of too much cerebrospinal fluid inside the spaces (ventricles) of the brain.

hydrostatic pressureThe pushing force a fluid puts on the walls of the space that holds it.

hyperactive bowel soundBowel sounds that are louder, more frequent or longer than normal when listening to the abdomen.

hyperactivityMore physical activity and restlessness than is usual for a person's age, with trouble staying still.

hyperbilirubinemiaToo much bilirubin, a yellow waste product of old red blood cells, in the blood.

hypercalcemiaA blood calcium level above normal.

hypercapniaToo much carbon dioxide in the blood, a PaCO2 above 45 mm Hg.

hyperchloremiaA blood chloride level above normal, over 106 mEq/L.

hyperemesis gravidarumSevere, ongoing nausea and vomiting in pregnancy that is much worse than ordinary morning sickness.

hyperglycemiaA blood glucose level above normal, over 100 mg/dL when fasting.

hyperkalemiaA blood potassium level above normal, over 5.0 mEq/L.

hyperlipidemiaHigher than healthy levels of fats (lipids), such as cholesterol or triglycerides, in the blood.

hypermagnesemiaA blood magnesium level above normal.

hypernatremiaA blood sodium level above normal, over 145 mEq/L.

hyperosmolarHaving more dissolved particles per unit of fluid than normal, so the fluid pulls water toward itself.

hyperparathyroidismOveractivity of the parathyroid glands, which make too much parathyroid hormone.

hyperphosphatemiaA blood phosphate (phosphorus) level above normal.

hyperpigmentationPatches of skin that are darker than the skin around them.

hyperplasiaAn increase in the number of cells in a tissue or organ, making it larger.

hypersensitivityAn overreaction of the immune system to a substance that is usually harmless.

hypertensionBlood pressure that stays higher than normal, at or above 130/80 mm Hg by current US guidelines.

hypertensive crisisA severe rise in blood pressure, generally to a systolic above 180 or a diastolic above 120 mm Hg.

hyperthermiaA body temperature that is higher than normal because the body takes in or makes more heat than it can lose.

hyperthyroidismA condition in which the thyroid gland makes too much thyroid hormone.

hypertrophyAn increase in the size of an organ or tissue because its cells grow larger.

hyperventilationBreathing faster or deeper than the body needs, so too much carbon dioxide is breathed out.

hypervolemiaA higher than normal volume of fluid in the blood vessels; also called fluid volume excess or fluid overload.

hypocalcemiaA blood calcium level below normal.

hypochloremiaA blood chloride level below normal, under 98 mEq/L.

hypoglycemiaA blood glucose level below normal, under 70 mg/dL.

hypokalemiaA blood potassium level below normal, under 3.5 mEq/L.

hypomagnesemiaA blood magnesium level below normal.

hyponatremiaA blood sodium level below normal, under 135 mEq/L.

hypoparathyroidismA condition in which the parathyroid glands make too little parathyroid hormone.

hypophosphatemiaA blood phosphate (phosphorus) level below normal.

hypospadiasA birth defect in which the opening of the urethra is on the underside of the penis instead of at the tip.

hypotensionBlood pressure lower than normal, generally below 90/60 mm Hg in an adult.

hypothalamusA small area at the base of the brain that controls body temperature, hunger, thirst, sleep and many hormones.

hypothyroidismA condition in which the thyroid gland makes too little thyroid hormone.

hypoventilationBreathing that is too slow or too shallow to remove enough carbon dioxide from the body.

hypovolemiaA lower than normal volume of fluid in the blood vessels; also called fluid volume deficit.

hypovolemicHaving too little blood or fluid in the blood vessels.

hypovolemic shockShock from a large loss of blood or body fluid, so there is too little volume in the blood vessels to supply the organs.

hypoxiaA lower than normal level of oxygen in the body's tissues.

hysterectomySurgery to remove the uterus.