Dictionary

Body systems

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

hemolysisThe breaking apart of red blood cells, which releases hemoglobin into the blood.

hemophiliaAn inherited disorder in which the blood lacks a clotting factor, so it does not clot normally.

hemoptysisCoughing up blood or blood-streaked mucus from the lungs or airways.

hemorrhageA large loss of blood from a blood vessel, inside the body or out of it.

hemorrhoidA swollen vein in or around the anus or lower rectum.

hemostasisThe stopping of bleeding, either by the body's own clotting process or by medical or surgical methods.

hepaticRelating to the liver.

hepatitisInflammation of the liver, most often caused by a virus.

hepatitis BA liver infection caused by the hepatitis B virus.

hepatitis B virusThe virus that causes hepatitis B, an infection of the liver.

hepatitis CAn infection of the liver caused by the hepatitis C virus.

hepatomegalyAn enlarged liver.

herniaA bulge of an organ or tissue through a weak spot in the muscle or tissue wall that normally holds it in.

herniationThe bulging or pushing of an organ or tissue through an opening or weak spot into a place where it does not belong.

herpes simplex virusA common virus that infects the skin and lining of the mouth or genitals and stays in the body for life.

HHSHyperosmolar hyperglycemic state: very high blood glucose with severe dehydration and little or no ketone buildup.

high blood pressureThe everyday name for hypertension: blood pressure that stays higher than normal.

hip fractureA break in the upper part of the thigh bone, near the hip joint.

Hirschsprung diseaseA condition present at birth in which a section of the large intestine has no nerve cells to move stool along.

hirsutismThick, dark hair growing in a male-type pattern, such as on the face, chest or back, in a woman.

histamineA chemical released by certain immune cells that widens blood vessels, makes them leaky and tightens airway muscles.

histologyThe study of body tissues under a microscope.

HITHeparin-induced thrombocytopenia: an immune reaction to heparin that lowers the platelet count.

HIVHuman immunodeficiency virus: a virus that infects and destroys immune cells called CD4 T cells.

HIV/AIDSHuman immunodeficiency virus infection and acquired immunodeficiency syndrome, its most advanced stage, written together.

hoarsenessA rough, strained or breathy voice that is harder to make or sounds different from normal.

Hodgkin lymphomaA cancer of the lymphatic system that starts in white blood cells called lymphocytes and has large abnormal cells called Reed-Sternberg cells.

homeostasisThe body's way of keeping its inside conditions, such as temperature, fluids and blood sugar, steady.

hopelessnessA feeling that things will not get better and that nothing a person does can change that.

hormoneA chemical messenger made by a gland or organ and carried in the blood to act on cells elsewhere in the body.

hormone replacement therapyTreatment with hormones, usually estrogen with or without a progestin, to replace hormones the body no longer makes enough of.

human papillomavirusA common group of viruses spread by close skin-to-skin contact, most often during sex.

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.