Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «H»:
Hydroxyapatite: A major component and an essential ingredient of normal bone and teeth. Hydroxyapatite makes up bone mineral and the matrix of teeth. It is hydroxyapatite that gives bones and teeth their rigidity.
Hydroxyapatite molecules can group together (crystalize) to form microscopic clumps....
Hydroxyapatite crystal disease
Hydroxyapatite crystal disease:The inflammation caused by hydroxyapatite crystals has been referred to as hydroxyapatite crystal disease.
Hydroxyapatite is a major component and an essential ingredient of normal bone and teeth, makes up bone mineral and the matrix of teeth, and gives bones and teet...
Hydroxytryptamine: See: Serotonin....
Hydroxyurea: A drug that inhibits the synthesis of DNA and so is classified as an antimetabolite. Hydroxyurea is used to treat a number of diseases, including chronic myeloid leukemia (CML), polycythemia vera, carcinoma of the head and neck, ovary, and cervix, melanoma, and sickle cell disease. Hyd...
Hygieia: In Greek mythology, a goddess considered to be the guardian or personification of health. Hygieia was the daughter of Asclepius, the god of healing. In Greek, "hygieia" means health....
Hygiene: The science of preventive medicine and
the preservation of health.
From the name of Hygeia, the daughter of Asklepios, the
Greek god of
medicine (whose staff with entwined snake is the symbol of
Asklepios (known to the Romans as Aesculapius) had a number
Hygiene hypothesis: A hypothesis that states that exposure to allergens in the environment early in life reduces the risk of developing allergies by boosting immune system activity. Conversely, relatively clean environment in early life would sway the immune system towards allergy-promoting response...
Hygiene theory: See: Hygiene hypothesis....
Hymen: A thin membrane which completely or partially
occludes the vaginal opening. The hymen is a fold of mucous membrane
usually present at birth at the orifice of the vagina. It is also
called the vaginal membrane (or, sometimes, the virginal membrane).
"Hymen" is a Greek word meaning "skin" or...
Hyoglossus: The muscle that permits the tongue to
be held on the floor of the mouth....
Hyper-: Prefix meaning "high, beyond, excessive, above normal" as in hypercalcemia (high calcium in the blood) and hypersensitivity. The opposite of hyper- is hypo-.
See also: Super-....
Hyper-IgD syndrome: A genetic disorder characterized by recurring attacks of chills and fever that usually start before the first birthday and last for 4 to 6 days, usually accompanied by swollen glands in the neck and abdominal pain with vomiting or diarrhea. Other symptoms may include headache, jo...
Hyperactivity: A higher than normal level of
activity. An organ can be described as hyperactive if it is
more active than usual. Behavior can also be hyperactive.
People who are hyperactive always seem to be in motion. They can't sit still; they may dash around or talk incessantly. Sitting still t...
Hyperadrenocorticism: Excess hormone called
"cortisol". Often called Cushing's syndrome, it is an extremely complex
condition that involves many areas of the body. It results from an excess of cortisol and
its effects on the human body. Common symptoms are thinning of the skin, weakness, w...
Hyperaldosteronism: Overproduction of the hormone aldosterone from the
outer portion (cortex) of the adrenal gland or a tumor containing that type of tissue.
Excess aldosterone (pronounced al-do-ster-one) results in low potassium levels
(hypokalemia), underacidity of the body (alkalosis), muscle wea...