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Hormones are produced by various organs and body tissues, but mainly by the endocrine glands, such as the pituitary, thyroid, and gonads (testes and ovaries). Each gland apparently synthesizes several kinds of hormones; the adrenal glands alone produce more than 25 varieties. The total number of hormones is still unknown, but each has its unique function and its own chemical formula. After a hormone is discharged by its parent gland into the capillaries or the lymph, it may travel a circuitous path through the bloodstream to exert influence on cells, tissues, and organs (target organs) far removed from its site of origin.
One of the best-known endocrine hormones is insulin, a protein manufactured by the beta cells of the islands of Langerhans in the pancreas that is important in carbohydrate metabolism. Other important hormones are thyroxine, an iodine-carrying amino acid produced by the thyroid gland; cortisone, a member of the steroid family from the adrenal glands; and the sex hormones, estrogen from the ovaries and androgen from the testes. Certain hormone substances can be synthesized in the laboratory for treatment of human disease. Animal hormones can also be used, as endocrine hormones are to some extent interchangeable among species. Extracts from the pancreas of cattle, for example, enabled diabetes sufferers to live normal lives even before the chemistry of insulin was fully understood.
Endocrine hormone synthesis and secretion is controlled and regulated by a closed-loop system. Negative feedback loops maintain optimal levels of each hormone in the body. If there are abnormally high levels of a hormone in the blood, feedback to the gland responsible for its production inhibits secretion. If there are abnormally low levels, the gland is stimulated to step up production and secretion. In this way a homeostatic balance is maintained. (See also endocrine glands.)
Ectopic hormones present serious problems for patients and add to the complexity of caring for those with certain kinds of neoplastic diseases. These hormones do not respond to the feedback mechanisms that regulate normal hormonal production; hence, surgery and destruction of the tumorous tissue by radiation and chemotherapy are the treatments of choice.
va·so·pres·sin (VP),(vā'sō-pres'in, vas-ō-),
antidiuretic hormone(ăn′tē-dī′ə-rĕt′ĭk, ăn′tī-)
antidiuretic hormone (ADH)
antidiuretic hormoneArginine vasopressin Endocrinology An octapeptide hormone synthesized in the hypothalamus and released from the posterior pituitary, which promotes renal tubular reabsorption of water by kidneys in response to ↑ osmolality/↓ plasma volume with ↑ sodium and solutes; ↓ osmolality–water excess results in ↓ secretion of ADH, thereby ↑ excretion of water to maintain fluid balance; ADH is ↑ in bronchogenic carcinoma, acute porphyria, hypothyroidism, Addison's disease, cirrhosis, hepatitis, hemorrhage, shock, CHF; ADH is ↓ with diabetes insipidus, viral infection, metastatic CA, sarcoidosis, TB, Langerhans cell histiocytosis/Hand-Schuller-Christian disease, syphilis, head trauma Therapeutic effects ADH is an antidiuretic and vasopressor, and used for diabetes insipidus
Synonym(s): antidiuretic hormone.
antidiuretic hormoneVasopressin. The hormone released by the rear part of the PITUITARY gland which acts on the kidneys to control water excretion. In the absence of this hormone, large quantities of urine are produced, as in DIABETES INSIPIDUS.
antidiuretic hormonesee ADH.
Antidiuretic hormone (vasopressin)
antidiureticagent reducing urine output
hormonechemical substance that acts locally or is carried via blood to another body part, to cause a regulatory effect on functional activity or structure
adrenocorticotrophic hormone; ACTH; corticotrophin; adrenocorticotrophin anterior pituitary hormone stimulating release of glucocorticoid and mineralocorticoid and sex hormones (androgens) from cortex of adrenal gland; plasma ACTH levels are reduced in Cushing's syndrome (due to excess production of adrenal cortex hormones) and raised in Addison's disease (due to reduced adrenal cortex function)
antidiuretic hormone; ADH; vasopressin anterior pituitary hormone; causes urine concentration by increasing resorption of solute at the distal convoluted tubule of nephron; absence of ADH causes diabetes insipidus
follicle-stimulating hormone; FSH anterior pituitary hormone; acts on ovaries/testes to influence the release of the sex hormones (oestrogen/testosterone), and induce sperm growth/ovulation
growth hormone; GH; somatotropin anterior pituitary hormone; acts on many tissues, inducing normal growth
luteinizing hormone; LH anterior pituitary hormone; acts on ovaries/testes to influence sex hormone release (oestrogen/testosterone) and induce sperm growth/ovulation