Glossary: H

H2-blockers

Medications used to treat gastroesophageal reflux disease (GERD) that decrease the amount of acid made by the stomach. The stomach lining has sites that react to a chemical normally found in the body called histamine. When histamine attaches to these sites, the stomach produces acid that aids in digestion of food. H2-blockers prevent the stomach from reacting to histamine, thereby decreasing stomach acid.

Haemophilus influenzae (Also called H. influenzae)

Represents a group of bacteria that may cause different types of infections in infants and children. H. influenzae most commonly causes ear, eye, or sinus infections, and pneumonia.

hair cells

sensory cells of the inner ear, which are topped with hair-like structures (stereocilia), which transform the mechanical energy of sound waves into nerve impulses.

halitosis

an oral health condition characterized by consistently odorous breath.

hallucinations

a strong perception of an event or object when no such situation is present; may occur in any of the senses (i.e., visual, auditory, gustatory, olfactory, or tactile).

hammertoe

a permanent sideways bend in the middle toe joint.

hamstrings

muscles located in the posterior compartment of the thigh.

handicap

barriers imposed by society, the environment, or attitudes that prevent a person with a disability from performing a role that is normal for that person.

hay fever

see rhinitis.

headache

pain or discomfort in the head or face area. Headaches can be single or recurrent in nature, and localized to one or more areas of the head and face.

headache (primary)

includes tension (muscular contraction), vascular (migraine), and cluster headaches not caused by other underlying medical conditions.

headache (secondary)

includes headaches that result from other medical conditions. These may also be referred to as traction headaches or inflammatory headaches.

hearing

series of events in which sound waves in the air are converted to electrical signals that are sent as nerve impulses to the brain where they are interpreted.

hearing aid

electronic device that brings amplified sound to the ear.

hearing disorder

disruption in the normal hearing process; sound waves are not converted to electrical signals and nerve impulses are not transmitted to the brain to be interpreted.

heart attack

also called myocardial infarction; damage to the heart muscle due to insufficient blood supply.

heart block

interrupted electrical impulse to heart muscles.

heart rate

the rate at which the heart beats. Normal heart rates range between 60 and 100 beats per minute.

heart valve prolapse

a condition of the heart valve in which it is partially open when it should be closed.

heart-lung machine

a machine that pumps blood during open heart surgery.

heartbeat

one complete contraction of the heart.

heartburn

painful, burning feeling in the chest caused by stomach acid flowing back into the esophagus.

heat exhaustion

a form of heat-related illness that is more severe than heat cramps and results from a loss of water and salt in the body. It occurs in conditions of extreme heat and excessive sweating without adequate fluid and salt replacement. Heat exhaustion occurs when the body is unable to cool itself properly. If left untreated, heat exhaustion can progress to heat stroke.

heat stroke

the most severe form of heat illness and is a life-threatening emergency. It is the result of long, extreme exposure to the sun, in which a person does not sweat enough to lower body temperature.

heel spur

a bone growth on the heel bone.

Heimlich maneuver

An emergency first-aid treatment, consisting of a series of under-the-diaphragm abdominal thrusts, used on a person choking on food or a foreign object.

Helicobacter pylori (H. pylori)

spiral-shaped bacterium found in the stomach. H. pylori damages stomach and duodenal tissue, causing ulcers. Previously called Campylobacter pylori.

hemarthrosis

bleeding into a joint.

hematocrit

the measurement of the percentage of red blood cells found in a specific volume of blood.

hematologist

a physician who specializes in the functions and disorders of the blood.

hematology

the scientific study of blood and blood-forming tissues.

hematoma

blood that collects under the skin or in an organ.

hematopathology

the study of blood, bone marrow, and the organs and tissues that use blood cells to perform their functions.

hematopoiesis

the process of producing and developing new blood cells.

hematuria

the presence of red blood cells (RBCs) in the urine.

hemochromatosis (Also called iron overload disease.)

a metabolic disorder that causes increased absorption of iron, which is deposited in the body tissues and organs. The iron accumulates in the body where it may become toxic and cause damage.

hemoglobin A1c (Also called HbA1c test.)

a test that shows the average amount of sugar in the blood over the last three months. The result will indicate if the blood sugar level is under control.

hemolytic anemia

one type of anemia in which the red blood cells are destroyed prematurely.

hemolytic uremic syndrome

a rare kidney disease that usually occurs in children.

hemophilia (Also called coagulation disorder.)

an inherited bleeding disorder caused by low levels, or absence of, a blood protein that is essential for clotting; hemophilia A is caused by a lack of the blood clotting protein factor VIII; hemophilia B is caused by a deficiency of factor IX.

hemorrhage

the medical term for bleeding.

hemorrhoidectomy

the surgical removal of hemorrhoids.

hemorrhoids

swollen blood vessels in and around the anus that cause itching, pain, and sometimes bleeding.

hepatic

related to the liver.

hepatic

inflammation of the liver that sometimes causese permanent damage; caused by viruses, drugs, alcohol, or parasites.

hepatitis A

a form of infectious hepatitis caused by the hepatitis A virus. The virus may be spread by fecal-oral contact, fecal-infected food or water, and may also be spread by a blood-borne infection (which is rare).

hepatitis B

a form of infectious hepatitis caused by the hepatitis B virus. Transmission of the hepatitis B virus occurs through blood and body fluid exposure such as blood, semen, vaginal secretions, or saliva.

hepatitis C

a form of infectious hepatitis caused by the hepatitis C virus. Transmission of the hepatitis C virus occurs primarily from contact with infected blood, but can also occur from sexual contact or from an infected mother to her baby.

hepatitis D

a form of infectious hepatitis caused by the hepatitis (Delta) virus. This form of hepatitis can only occur in the presence of hepatitis B. Transmission of hepatitis D occurs the same way as hepatitis B.

hepatitis E

a form of infectious hepatitis caused by the hepatitis E virus. This form of hepatitis is similar to hepatitis A. Transmission occurs through fecal-oral contamination. Hepatitis E is most common in poorly developed countries and is rarely seen in the US.

hepatitis G

the newest form of infectious hepatitis. Transmission is believed to occur through blood and is seen in IV drug users, individuals with clotting disorders, such as hemophilia, and individuals who require hemodialysis for renal failure.

hepatobiliary scintigraphy

an imaging technique of the liver, bile ducts, gallbladder, and upper part of the small intestine.

hepatologist

physician who specializes in liver diseases.

hepatology

field of medicine concerned with the functions and disorders of the liver.

hernia

a protrusion of part of an organ through the muscle that surrounds it.

herpes genitalis

an infection caused by the herpes simplex virus (HSV) and usually spread by sexual contact. Symptoms may include painful blisters or open sores in the genital area, which may be preceded by a tingling or burning sensation in the legs, buttocks, or genital region. The herpes sores usually disappear within a few weeks, but the virus remains in the body and the lesions may recur from time to time.

herpes zoster (Also called shingles.)

a common viral infection of the nerves, characterized by a painful skin rash of small blisters anywhere on the body.

hiatal hernia

small opening in the diaphragm that allows the upper part of the stomach to move up into the chest and causes heartburn from stomach acid flowing back up through the opening.

high blood glucose

a condition that occurs in people with diabetes when their blood glucose levels are too high.

high blood pressure

a condition in which the blood circulates through the arteries with too much force.

high density lipoprotein (HDL)

a protein in the blood plasma (the "good" cholesterol) that promotes breakdown and removal of cholesterol from the body.

hip

the region on each side of the pelvis; made up of three sections: ilium, ischium, and pubis; the upper part of the femur (upper leg bone) fits into the hip via a ball-and-socket joint; the socket is a cup-shaped bone of the pelvis, called the acetabulum, and the ball is the head of the femur.

Hirschsprung's disease

Birth defect in which some nerve cells are lacking in the large intestine.

hirsutism

excessive hairiness.

histamine

a chemical present in cells throughout the body that is released during an allergic reaction and one of the substances responsible for the symptoms of inflammation.

histrionic personality disorder

persons with this disorder are overly conscious of their appearance, are constantly seeking attention, and often behave dramatically in situations that do not warrant this type of reaction. The emotional expressions of persons with histrionic personality disorder are often judged as superficial and exaggerated.

hives (Also called urticaria.)

a condition in which red, itchy, and swollen areas appear on the skin usually as an allergic reaction from eating certain foods or taking certain medications.

hoarseness

abnormally rough or harsh-sounding voice caused by vocal abuse and other disorders.

Hodgkin's disease

A type of lymphoma, a cancer in the lymphatic system; a rare disease, accounting for less than 1 percent of all cases of cancer in the US, and occurs most often in people between the ages of 15 and 34, and in people over age 55. Hodgkin's disease causes the cells in the lymphatic system to abnormally reproduce, eventually making the body less able to fight infection. Steady enlargement of lymph glands, spleen, and other lymphatic tissue occurs.

Holter monitor

An EKG recording done over a period of 24 or more hours.

hormone replacement therapy (HRT)

use of the female hormones estrogen and progestin (a synthetic form of progesterone) to replace those hormones the body no longer produces after menopause.

hormone therapy

the use of hormones, medications, or surgery to suppress (block) or mimic hormones and alter the growth of hormone sensitive cancer.

hormones

chemical substances created by the body that control numerous body functions.

hospice

literal meaning "a place of shelter." Today it refers to supportive care of a terminally ill patient.

human chorionic gonadotropin

hormone produced by the placenta during early pregnancy.

human papillomaviruses (HPVs)

viruses that can cause warts. Some HPVs are sexually transmitted and cause wart-like growths on the genitals. HPV is a major risk factor for cervical cancer.

humerus

the bone of the upper arm.

hyaloid canal

narrow passageway that allows blood to flow through the eye.

hydrochloric acid

acid made in the stomach that works with pepsin and other enzymes to break down proteins.

hydrocortisone

a hormone secreted by the adrenal cortex which affects metabolism.

hydronephrosis

a condition that occurs as a result of urine accumulation in the upper urinary tract. This usually occurs from a blockage somewhere along the urinary tract.

hydrotherapy

rehabilitation exercises performed in water.

hyperactive

describes a situation in which a body tissue is especially likely to have an exaggerated reaction to a particular situation.

hyperextension

active or passive force which takes the joint into extension, but beyond its normal range.

hyperglycemia

a condition that occurs in people with diabetes when their blood glucose levels are too high.

hyperopia

farsightedness

hyperplasia

an abnormal increase in the number of cells in an organ or tissue.

hypertension

a condition in which the blood circulates through the arteries with too much force; high blood pressure.

hypertrophic obstructive cardiomyopathy (HOCM)

a bulge in the ventricle that causes impeded blood flow.

hypertrophy

an increase in the size of tissue.

hypogeusia

diminished sensitivity to taste.

hypoglycemia

condition in which the blood sugar is lower than normal.

hypomobility

a decrease in the normal range of joint movement.

hyposmia

diminished sensitivity to smell.

hypotension

abnormally low blood pressure.

hypothalamus

small structure at the base of the brain that regulates many body functions, including appetite and body temperature.

hypothermia

an abnormally low body temperature brought on by staying in cold temperatures for a long period of time; a life-threatening emergency.

hypoxia

abnormally low oxygen content in the organs and tissues of the body.

hysterectomy

surgical removal of the uterus.

hysterosalpingography

x-ray examination of the uterus and fallopian tubes that uses dye and is often performed to rule out tubal obstruction.

hysteroscope

visual examination of the canal of the cervix and the interior of the uterus using a viewing instrument (hysteroscope) inserted through the vagina.

hysteroscopy

a visual inspection of the cervical canal and uterine cavity with an endoscope.

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