Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «H»:
Haemophilus influenzae genome
Haemophilus influenzae genome: See: H. flu genome....
Haemophilus influenzae type B
Haemophilus influenzae type B: Abbreviated as HIB, a bacterium capable of causing a range of diseases including ear infections, cellulitis (soft tissue
infection), upper respiratory infections, pneumonia, and such serious invasive infections as meningitis with potential brain damage and epiglottiti...
Haemophilus influenzae type B (HIB) immunization
Haemophilus influenzae type B (HIB) immunization: This kind of immunization is designed to prevent diseases caused by Haemophilus influenzae type B (HIB), a bacteria responsible for a range of serious "invasive"
diseases including meningitis with potential brain damage and
epiglottitis with airwa...
Hahnemann, Samuel: (1755-1843) German physician and founder of homeopathy....
Hair follicle: A sac from which a hair grows and into which the sebaceous (oil) glands open. The follicle is lined by cells derived from the epidermal (outside) layer of the skin.
Each follicle normally goes through a five-year cycle of growth and rest, with about 90% of the follicles growing hair ...
Hair loss: Hair loss is the thinning of hair on the scalp. The medical term for hair loss is alopecia. Alopecia can
be temporary or permanent. The most common form of hair loss occurs gradually
and is referred to as "androgenetic alopecia," meaning that a combination of
hormones (androgens are ma...
Hair of the dog
Hair of the dog: An alcoholic chaser reputed to relieve a hangover, usually needed the morning after imbibing too much alcohol. There is no scientific evidence as to the efficacy of this time-honored treatment for a hangover.
The saying originated in the belief that a cure for hydrophobia (rabies) ...
Hair, exclamation point
Hair, exclamation point: Exclamation point hair is a key diagnostic finding in a disorder called alopecia areata.
Alopecia areata is patchy baldness (alopecia means baldness and areata means occurring in patches) which
typically begins with patchy hair loss on the scalp and sometimes
Hair, lanugal: The downy hair on the body of the fetus and newborn baby.
The lanugal hair (or lanugo) is the first hair to be produced by the fetal hair follicles. It is very fine, soft and usually is unpigmented.
The lanugal hair is prenatal hair. It appears at about 5 months of gestation and begi...
Hair-on-end skull: Thin fine linear extensions radiating out from the skull that look on an X-ray like hair standing "on-end" from the skull, an appearance associated with hemolytic anemias such as sickle cell disease and thalassemia.
The "hair" represents the accentuated trabeculae extending betwe...
Hairball: A wad of swallowed hair. Hairballs can sometimes
be found to cause blockage of the digestive system, especially at the
exit of the stomach.
Interestingly, in the Far East culture, hairballs are felt to have
Also called a trichobezoar....
Hairy cell leukemia
Hairy cell leukemia: A form of chronic leukemia in which malignant B-lymphocytes (a type of white blood cell) are seen in the bone marrow, spleen, and peripheral blood and when viewed under the microscope, these cells appear to be covered with tiny hair-like projections. Hairy cell leukemia represe...
Halitosis: bad breath. Causes of halitosis include dietary factors, poor oral hygiene, tobacco use, certain chronic medical
conditions, or dry mouth (as a side effect of medications, from mouth breathing, or from problems with the salivary glands leading to decreased production of saliva)....
Hallervorden-Spatz disease: A genetic disorder in which there is progressive neurologic degeneration with the accumulation of iron in the brain. The gene for the disease is on chromosome 20 in region 20p13-p12.3.
The syndrome was first described by Julius Hallervorden and Hugo Spatz in 1922 in 5 si...
Hallucination: A profound distortion in a person's perception of reality, typically accompanied by a powerful sense of reality. An hallucination may be a sensory experience in which a person can see, hear, smell, taste, or feel something that is not there.
The types of hallucinations include: