bedwetting Involuntary urination in bed after the usual age of toilet training. Also known as nighttime enuresis and nocturnal enuresis. It may be caused by incomplete development of bladder control, a sleep or arousal disorder, bladder or kidney disease, neurological problems, or psychological causes (such as fear of the dark that prevents the child from…
bedsore A painful, often reddened area of degenerating, ulcerated skin that is caused by pressure and lack of movement and is worsened by exposure to urine or other irritating substances. Untreated bedsores can become seriously infected or gangrenous. Bedsores are a major problem for patients who are confined to a bed or wheelchair, and they…
bedbug A blood-sucking bug in the Cimex family that lives hidden in bedding or furniture and comes out at night to bite its victims.
Beau’s lines Transverse lines or grooves across the fingernails, or transverse depressions in the nail plate, from temporary disturbance of cell division where the nail develops. The condition may be caused by local disease or injury of the nail fold, or from a generalized condition such as an illness or a drug, for example, chemotherapy.
BCG Bacille Calmette Guérin, a weakened (attenuated) version of a bacterium called Mycobacterium bovis that is closely related to Mycobacterium tuberculosis, the agent responsible for tuberculosis. See tuberculosis vaccination.
battle fatigue The World War II name for what is known today as post-traumatic stress disorder (PTSD). See also post-traumatic stress disorder.
battered child syndrome A condition in which a person has skeletal fractures, especially multiple injuries of various ages, that result from child abuse. All states in the US have adopted laws mandating the reporting of suspected instances of child abuse. See also child abuse.
basophilic leukocyte See basophil.
basophil A type of white blood cell (leukocyte) with coarse, bluish-black granules of uniform size within the cytoplasm. Basophils are so named because their cytoplasmic granules stain with basic dyes. Basophils normally constitute 0.5 to 3 percent of the peripheral blood leukocytes, and contain histamine and serotonin. Also known as a basophilic leukocyte.
basement membrane A thin membrane that is composed of a single layer of cells.
baseline Information or data gathered at the beginning of a period from which variations that subsequently develop are compared.
base sequence The particular order of nucleotide bases in a DNA molecule.