Medical terms - Letter H (page 4) | MedicalVocabulary.org

Heart-lung machine

A machine that does the work both of the heart (pump blood) and the lungs (oxygenate the blood). Used, for example, in open heart surgery. Blood returning to the heart is diverted through the machine before returning it…
Heartburn

An uncomfortable feeling of burning and warmth occurring in waves rising up behind the breastbone (sternum) toward the neck. It is usually due to gastroesophageal reflux disease (GERD), the rise of stomach acid back up…
Heartworm

Dirofilaria immitis. A common parasite of dogs in many parts of the world that occurs in other animals, including cats, but rarely infects humans. The adult worms, which are up to 10 inches (25 cm) in length, typically…
Heat cramps

Heat cramps: Painful muscle spasms in the abdomen, arms, or legs following strenuous activity. The skin is usually moist and cool and the pulse is normal or slightly raised. Body temperature is mostly normal. Heat…
Heat exhaustion

Heat exhaustion: A warning that the body is getting too hot. The person may be thirsty, giddy, weak, uncoordinated, nauseous, and sweating profusely. The body temperature is usually normal and the pulse is normal or…
Heat index

The temperature the body feels when heat and humidity are combined. The body dissipates heat by varying the rate and depth of blood circulation, by losing water through the skin and sweat glands, and as a last resort…
Heat prostration

Overheating of the body due to extreme weather conditions. Unrelieved hyperthermia can lead to collapse and death, particularly in the elderly. Prevention via air conditioning, ventilation, and drinking extra water is…
Heat rash

Heat rash: Heat rash is an irritation of the skin that results from excessive sweating during hot and humid weather. Heat rash appears as clusters of red pimples or blisters on the skin. It is more likely to occur on…
Heat stroke

Heat stroke: A core body temperature that rises above 104°F (40°C) accompanied by hot, dry skin and central nervous system abnormalities such as delirium, convulsions, or coma. Heat stroke that results from exposure to…
Heat syncope

Sudden dizziness, feeling faint ans sometimes fainting experienced after exercising in the heat. The skin appears pale and sweaty but is generally moist and cool. The pulse may be weakened, and the heart rate is usually…
Heat-related illness

A person with symptoms including headache, nausea, and fatigue after exposure to heat probably has some measure of a heat-related illness. It is important to recognize the difference between the very serious condition…
Heatliness

A characteristic of certain foods or other substances believed to cause emotional or physical reactions associated with temper, fever, passion, and excess. Coolness and heatliness are the yin and yang of a principle of…
Heberden disease

>Angina pectoris, chest pain that is often severe and crushing, due to an inadequate supply of oxygen to the heart muscle. >Osteoarthritis of the small joints with nodules (Heberden nodes) in and about the last joint of…
Heberden node

A small fixed bump on the finger, usually at the last joint of the finger, Heberden's node is a calcified spur of the joint (articular) cartilage and is a sign of osteoarthritis. Named for the English physician William…
Hecht syndrome

A striking genetic disorder in which abnormally short muscles in the jaw make it impossible to open the mouth fully (trismus) and abnormally short muscles in the hands keep the fingers straight when the hand is flexed…
Hecht's pneumonia

Pneumonia: Also known as giant cell pneumonia, this is a deadly but fortunately rare complication of measles. It tends to strike children who are immunodeficient as from leukemia or HIV/AIDS. The postmortem examination…
Hecht-Beals syndrome

See: Hecht syndrome
Hedonophobia

An abnormal, excessive, and persistent fear of pleasure. Sufferers with this most puritanical of phobias typically feel guilty about experiencing pleasure even though they usually realize rationally there is nothing at…
Heebie-jeebies

Extreme nervousness. A term coined by the America cartoonist Billy DeBeck (1890-1942) in his comic strip Barney Google
Heel bone

Formally called the calcaneus. A more or less rectangular bone at the back of the foot. The words 'calcaneus' and 'calcium' come from the same source.
Heel prick

A procedure in which the heel is pricked and then a small amount of the blood is collected, usually with a narrow-gauge ('capillary') glass tube or a filter paper. The heel prick is now the most common way to draw blood…
Heel spur

A bony spur projecting from the back or underside of the heel that often makes walking painful. Spurs at the back of the heel are associated with inflammation of the Achilles tendon (Achilles tendinitis) and cause…
Heel stick

A procedure in which a newborn baby's heel is pricked and then a small amount of the blood is collected, usually with a narrow-gauge ('capillary') glass tube or a filter paper. The heel stick is now the most common way…
Height growth

See: Normal growth
Heights, fear of

An irrational unreasonable fear of heights is called acrophobia. From the Greek 'acron', height + 'phobos', fear
Heimlich maneuver

An emergency treatment for obstruction of the airway in adults. It may be needed when someone chokes on a piece of food that has 'gone down the wrong way.' To perform the Heimlich maneuver, stand behind the victim, wrap…
Hejama

Alternate Arabic term for cupping. The preferred Arabic term for this practice is al-hijamah. See: Cupping
HeLa cell

One of the cells grown from the cervical cancer of a young African-American woman, Henrietta Lacks. HeLa cells were the first human cells to be continuously grown in culture. The cells were first cultured in February…
Helical CAT scan

A conventional computerized axial tomography scan (CAT scan or CT scan) is an x-ray procedure which combines many x-ray images with the aid of a computer to generate cross-sectional views and, if needed…
Helicase

An enzyme that unwinds double-strand DNA into two single DNA strands
Helicobacter heilmannii

A bacteria that infects most cats, dogs and pigs and, in them, causes stomach inflammation (gastritis). H. heilmannii is not usually transmitted from animals to people. But people who have been infected by H. heilmannii…
Helicobacter pylori

Helicobacter pylori: Bacteria that cause stomach inflammation (gastritis) and ulcers in the stomach. This bacteria is the most common cause of ulcers worldwide. It is often referred to as H. pylori. H. pylori infection…
Helix, alpha

See: Alpha helix
Helix, double

The structure of DNA with the two strands of DNA spiraling about one other. The double helix looks something like an immensely long ladder twisted into a helix, or coil. The sides of the 'ladder' are formed by a…
HELLP syndrome

A syndrome featuring a combination of 'H' for hemolysis (the breakdown of red blood cells), 'EL' for elevated liver enzymes, and 'LP' for low platelet count (an essential blood clotting element). The HELLP syndrome is a…
Helmet, bicycle

A well-known but often neglected device designed to protect the head of a bicyclist. Helmets decrease the risk of head injuries (traumatic brain damage) by about 85%. Unfortunately, only about 18% of bicyclists in the…
Helminth

A worm classified as a parasite. (A parasite is a disease-causing organism that lives on or in a human or another animal and derives its nourishment from its host.) Lice are examples of parasites that live on humans…
Helminthology, medical

See: Medical helminthology
Helminthphobia

An abnormal and persistent fear of being infested with parasitic worms called helminths. The eggs of these worms can contaminate air and water, particularly where hygiene is poor. They can also contaminate foods such as…
Helper cell

A type of T cell that participates in the immune response by recognizing foreign antigens and secreting substances called cytokines that activate T and B cells. Helper cells fall into two main classes: those that…
Hem-onc

Short for Hematology-oncology
Hemangioma

A birth irregularity where a localized tissue mass grows rich in small blood vessels. Capillary hemangiomas are composed nearly entirely of tiny capillary vessels. Cavernous hemangiomas are composed of blood- filled…
Hemangioma, capillary

A type of hemangioma (a benign tumor formed by a collection of excess blood vessels) that is composed almost entirely of tiny capillary vessels. Capillary hemangiomas may be located anywhere on the body but they are…
Hemangioma, cavernous

A type of hemangioma composed of blood-filled 'lakes' and channels. It is typically raised and red or purplish. A cavernous hemangioma may diminish in size following trauma, bleeding or ulceration but it rarely…
Hemangioma, hepatic

A common benign tumor of the liver made up of small blood vessels. Hepatic hemangioma is the most common benign liver tumor and is 4-6 times more common in women than men (female hormones may promote its formation and…
Hemarthrosis

Blood in a joint.
Hematemesis

The medical term for bloody vomitus. The word 'hematemesis' is made up of 'hema-', blood + 'emesis', vomit = bloody vomit.
Hematochezia

Bright red blood in the stool, usually from the lower gastrointestinal tract -- the colon or rectum -- or from hemorrhoids. The term 'hematochezia' is rarely used. 'Bright red blood in the stool' is more widely used…
Hematocrit

Hematocrit: The proportion of the blood that consists of packed red blood cells. The hematocrit is expressed as a percentage by volume. The red cells are packed by centrifugation. For example, an hematocrit of 25% means…
Hematologist

A physician who is specially trained in the diagnosis, treatment, and prevention of diseases of the blood and bone marrow as well as the immunologic, hemostatic (blood clotting) and vascular systems. Because of the…