- : A chemical substance produced in the body that controls and regulates the activity of certain cells or organs. Many hormones are secreted by specialized glands such as the thyroid gland. Hormones are essential for every activity of daily living, including the processes of digestion, metabolism, growth, reproduction, and mood control. Many hormones, such as the neurotransmitters, are active in more than one physical process. Examples of hormones include aldosterone, antidiuretic hormone(ADH), cortisol, erythropoietin, estrogen, human chorionic gonadotropin (hCG), parathormone, progesterone, and testosterone. A hormone originally denoted a chemical made by a gland for export to another part of the body. Now a hormone is more broadly any chemical, irrespective of whether it is produced by a special gland or not, for export or domestic use, that "controls and regulates the activity of certain cells or organs.". The word "hormao" which means "I set in motion" or "I stir up" was used in ancient Greece to covey the "vital principle" of "getting the juices flowing." The word "hormone" was resurrected in 1902 (not 1906, as the Oxford English Dictionary states) by the English physiologists Wm. M. Bayliss and Ernest H. Starling who that year reported their discovery of a substance made by glands in the small intestine that stimulated pancreatic secretion. They called the substance "secretin" and dubbed it a "hormone", the first known hormone.
* * *A chemical substance, formed in one organ or part of the body and carried in the blood to another organ or part; depending on the specificity of their effects, hormones can alter the functional activity, and sometimes the structure, of just one organ or tissue or various numbers of them. A number of hormones are formed by ductless glands, but secretin, cholecystokinin, and pancreozymin, formed in the gastrointestinal tract, by definition are also hormones. For hormones not listed below, see specific names. [G. hormon, pres. part. of hormao, to rouse or set in motion]- adrenal androgen-stimulating h. (AASH) a putative pituitary h. that may be responsible for increased secretion of adrenal androgens at the time of puberty.- adrenocortical hormones hormones secreted by the human adrenal cortex; e.g., cortisol, aldosterone, corticosterone.- adrenocorticotropic h. (ACTH) the h. of the anterior lobe of the hypophysis that governs the nutrition and growth of the adrenal cortex, stimulates it to functional activity, and also possesses extraadrenal adipokinetic activity; it is a polypeptide containing 39 amino acid s, but exact structure varies from one species to another; sometimes prefixed by α to distinguish it from β-corticotropin. The first 13 amino acid s at the N-terminal region are identical to α-melanotropin. SYN: adrenocorticotropin, adrenotropic h., adrenotropin, corticotropic h., corticotropin (1).- adrenomedullary hormones hormones produced by the adrenal medulla, particularly the catecholamines epinephrine and norepinephrine.- adrenotropic h. SYN: adrenocorticotropic h..- androgenic h. any h. that produces a masculinizing effect; of the naturally occurring androgenic hormones, testosterone is the most potent.- anti-müllerian h. SYN: müllerian inhibiting substance.- cardiac h. SYN: herz h..- corticotropic h. SYN: adrenocorticotropic h..- corticotropin-releasing h. (CRH) a factor secreted by the hypothalamus that stimulates the pituitary to release adrenocorticotropic h.. SYN: corticotropin-releasing factor.- ectopic h. a h. formed by tissue outside the normal endocrine site of production; e.g., adrenocorticotropic h. produced by a bronchogenic carcinoma. SYN: inappropriate h..- erythropoietic h. 1. generally, any h. that promotes the formation of red blood cells, e.g., testosterone; 2. SYN: erythropoietin.- gastrointestinal h. any secretion of the gastrointestinal mucosa affecting the timing and quantity of various digestive secretions ( e.g., secretin) or causing enhanced motility of the target organ ( e.g., cholecystokinin).- gonadal hormones SYN: sex hormones.- heart h. SYN: herz h..- herz h. a substance present in extracts of cardiac tissue that augments cardiac contraction; possibly adenosine, a catecholamine, or some nonspecific stimulant present generally in tissues. SYN: cardiac h., heart h..- hypophysiotropic h. a h. that stimulates the rate of secretion of hypophysial hormones; e.g., a releasing factor; hypothalamic (regulatory) factor.- inappropriate h. SYN: ectopic h..- lipid-mobilizing h. SYN: lipotropin.- local h. a metabolic product secreted by one set of cells that affects the function of nearby cells; an autacoid; e.g., prostaglandins and neurotransmitters.- mammotropic h. SYN: prolactin.- parathyroid h. (PTH) a peptide h. formed by the parathyroid glands; it raises the serum calcium levels when administered parenterally by causing bone resorption, reducing renal clearance of calcium and increasing efficiency of calcium absorption in the intestine. It acts in conjunction with calcitonin and other hormones. SYN: parathormone, parathyrin.- proparathyroid h. the immediate precursor of parathyroid h.; proparathyroid differs from parathyroid h. by an N-terminal hexapeptide extension.- releasing h. (RH) SYN: releasing factors.- sex hormones a general term covering those steroid hormones that are formed by testicular, ovarian, and adrenocortical tissues, and that are androgens or estrogens. SYN: gonadal hormones.- steroid hormones those hormones possessing the steroid ring system; e.g., androgens, estrogens, adrenocortical hormones.- tissue hormones hormones synthesized by cells other than those in the endocrine system. Cf.:endocrine hormones.- tropic hormones, trophic hormones those hormones of the anterior lobe of the pituitary that affect the growth, nutrition, or function of other endocrine glands ( e.g., TRH, ACTH).- vertebrate hormones hormones synthesized in vertebrates.
* * *hor·mone 'hȯr-.mōn n1 a) a product of living cells that circulates in body fluids (as blood) or sap and produces a specific often stimulatory effect on the activity of cells usu. remote from its point of origin called also internal secretion see PLANT HORMONEb) a synthetic substance that acts like a hormone2) sex hormonehor·mone·like -.līk adj
* * *n.a substance that is produced in one part of the body (by an endocrine gland, such as the thyroid, adrenal, or pituitary), passes into the bloodstream and is carried to other (distant) organs or tissues, where it acts to modify their structure or function. Examples of hormones are corticosteroids (from the adrenal cortex), growth hormone (from the pituitary gland), and androgens (from the testes).
* * *hor·mone (horґmōn) [Gr. hormaein to set in motion, spur on, from hormē impulse] a chemical substance produced in the body by an organ, cells of an organ, or scattered cells, having a specific regulatory effect on the activity of an organ or organs. The term was originally applied to substances secreted by endocrine glands and transported in the bloodstream to distant target organs, but later it was applied to various substances having similar actions but not produced by special glands. See also endocrine system, under system. hormonal, hormonic adj
Medical dictionary. 2011.