eosinophilia An abnormally high number of eosinophils in the blood. Normally, eosinophils constitute 1 percent to 3 percent of the peripheral blood leukocytes, at a count of 350 to 650 per cubic millimeter. In areas of the world where parasite diseases are common, they are the usual cause of eosinophilia. In developed nations, eosinophilia is…
eosinophil A normal type of white blood cell that has coarse granules within its cytoplasm. Eosinophils are produced in the bone marrow and migrate to tissues throughout the body. When a foreign substance enters the body, other types of white blood cells (lymphcytes and neutrophils) release substances to attract eosinophils and then release toxic substances…
enzyme-linked immunosorbent assay See ELISA.
enzyme defect A disorder resulting from a deficiency (or functional abnormality) of an enzyme. For example, newborns are routinely screened for certain enzyme defects, such as phenylketonuria (PKU) and galactosemia.
enzyme A protein or protein-based molecule that speeds up a chemical reaction in a living organism. An enzyme acts as a catalyst for specific chemical reactions, converting a specific set of reactants (substrates) into specific products. Without enzymes, life as we know it would not exist. Errors in the design of enzymes are responsible for…
enzootic Endemic in animals. An enzootic disease is constantly present in an animal population, but usually only affects a small number of animals at any one time.
environmental tobacco smoke See secondhand smoke.
enuresis Involuntary urination, which may be caused by a variety of factors, including disorders of the kidneys, bladder, or ureter, and poor control of the muscles that control release of urine. Enuresis is also occasionally associated with neurological disorders, such as Tourette syndrome, particularly in children. Nighttime (nocturnal) enuresis may be related to any of…
enucleation The surgical removal of an eye. Enucleation is done under drastic circumstances such as to remove a malignant tumor in the eye or to relieve intolerable pain in a blind eye. Following enucleation, an artificial eye (ocular prosthesis) is implanted as a cosmetic substitute for the real eye.
Entoderm See endoderm.
enterovirus A virus that comes into the body through the gastrointestinal tract and thrives there, often moving on to attack the nervous system. Enteroviruses include the polioviruses, rhinoviruses, and echoviruses. See also polio.
enterostomy An operation that opens the small intestine and brings it through the abdominal wall to create a new opening (stoma) to permit intestinal draining. See also colostomy; ostomy.