hormone

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Related to anterior pituitary hormone: adenohypophysis

hormone

hormone, secretory substance carried from one gland or organ of the body via the bloodstream to more or less specific tissues, where it exerts some influence upon the metabolism of the target tissue. Normally, various hormones are produced and secreted by the endocrine glands (see endocrine system), including the pituitary, thyroid, parathyroids, adrenals, ovaries, testes, pancreatic islets, certain portions of the gastrointestinal tract, and the placenta, among the mammalian species. As lack of any one of them may cause serious disorders, many hormones are now produced synthetically and used in treatment where a deficiency exists. The hormones of the anterior pituitary include thyrotropin, adrenocorticotropic hormone, the gonadotropic hormones, and growth hormone; the posterior pituitary secretes antidiuretic hormone, prolactin, and oxytocin. The thyroids secrete thyroxine and calcitonin, and the parathyroids secrete parathyroid hormone. The adrenal medulla secretes epinephrine and norepinephrine while the cortex of the same gland releases aldosterone, corticosterone, cortisol, and cortisone. The ovaries primarily secrete estrogen and progesterone and the testes testosterone. The adrenal cortex, ovaries, and testes in fact produce at least small amounts of all of the steroid hormones. The islets of Langerhans in the pancreas secrete insulin, glucagon, and somatostatin. The kidneys also produce erythropoietin, which produces erythrocytes (red blood cells). The passage of chyme (see digestive system) from the stomach to the duodenum causes the latter to release secretin, which stimulates the flow of pancreatic juice. The duodenum can also be stimulated by the presence of fats in the chyme to secrete cholecystokinin, a hormone that stimulates the gall bladder to contract and release bile. There is evidence that the upper intestine secretes pancreatozymin, which enhances the amount of digestive enzymes in the pancreatic juice. In addition, the pyloric region of the stomach secretes gastrin, a hormone that increases the secretion of hydrochloric acid into the stomach. The placenta has been shown to secrete progesterone and chorionic gonadotropin. There is evidence that it even contains a substance similar to growth hormone. Insects have a unique hormonal system that includes ecdysone, a steroid that influences molting and metamorphosis, and juvenile hormone, needed for early development. Plants, too, have a hormonal system, which includes the auxins, the gibberellins, the cytokinins, and substances associated with the formation of flowers, tubers, bulbs, and buds. Ethylene is said to function as a hormone in plants, acting to hasten the ripening of fruits.
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Hormone

One of the chemical messengers produced by endocrine glands, whose secretions are liberated directly into the bloodstream and transported to a distant part or parts of the body, where they exert a specific effect for the benefit of the body as a whole. The endocrine glands involved in the maintenance of normal body conditions are pituitary, thyroid, parathyroid, adrenal, pancreas, ovary, and testis. However, these organs are not the only tissues concerned in the hormonal regulation of body processes. For example, the duodenal mucosa, which is not organized as an endocrine gland, elaborates a substance called secretin which stimulates the pancreas to produce its digestive juices. The placenta is also a very important hormone-producing tissue. See separate articles on the individual glands.

The hormones obtained from extracts of the endocrine glands may be classified into four groups according to their chemical constitution: (1) phenol derivatives, such as epinephrine, norepinephrine, thyroxine, and triiodothyronine; (2) proteins, such as the anterior pituitary hormones, with the exception of adrenocorticotropic hormone (ACTH), human chorionic gonadotropin, pregnant-mare-serum gonadotropin, and thyroglobulin; (3) peptides, such as insulin, glucagon, ACTH, vasopressin, oxytocin, and secretin; and (4) steroids, such as estrogens, androgens, progesterone, and corticoids. Hormones, with a few exceptions like pituitary growth hormone and insulin, may also be classified as either tropic hormones or target-organ hormones. The former work indirectly through the organs or glands which they stimulate, whereas the latter exert a direct effect on peripheral tissues. See Endocrine system (vertebrate)

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.

hormone

[′hȯr‚mōn]
(biochemistry)
A chemical messenger produced by endocrine glands and secreted directly into the bloodstream to exert a specific effect on a distant part of the body.
An organic compound that is synthesized in minute quantities in one part of a plant and translocated to another part, where it influences a specific physiological process.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

hormone

1. a chemical substance produced in an endocrine gland and transported in the blood to a certain tissue, on which it exerts a specific effect
2. an organic compound produced by a plant that is essential for growth
3. any synthetic substance having the same effects
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Immunohistochemistry (IHC) for specific anterior pituitary hormones (GH, adrenocorticotropic hormone [ACTH], prolactin [PRL], [alpha] subunit [ASU], follicle-stimulating hormone [FSH], thyroid-stimulating hormone, and luteinizing hormone [LH]) highlights the assortment of cell types in any compressed normal anterior pituitary gland in a specimen.
In this study, we examine an exploratory set of pituitary adenomas using IHC stains for Pit-1, SF-1, [alpha] subunit, CAM5.2, and standard anterior pituitary hormones. Correlation analysis and unsupervised learning approaches (cluster analyses) are used to see whether the underlying biology was reflected in our immunohistochemical panel.
To evaluate the proposed algorithm for accuracy and efficiency, these stepwise diagnoses were compared with the reference diagnosis and total stains used in the final algorithm were compared with the number used in our prior algorithm, which included IHC for all 6 anterior pituitary hormones plus CAM5.2 in the setting of GH or PRL staining.
Except for erythrocyte sedimentation rate of 88mm/h and low levels of anterior pituitary hormones, his biochemical test results were unremarkable.
Anterior pituitary hormones: Anterior pituitary evaluation was carried out pre-operatively at baseline and at 12 wk post-operatively for all patients.
Adaptation of anterior pituitary hormones to chronic noise stress in rats.
Tumor cells are negative for anterior pituitary hormones, keratin, vimentin, desmin, and neuron-specific enolase.[7] Although glial fibrillary acidic protein is typically reported as negative in GCTs of the infundibulum, glial fibrillary acidic protein has been demonstrated in tumor cells by electron immunocytochemistry.[8] It is suggested that GCTs and their tumorlet precursors derive from pituicytes and thus are astrocytic in nature and therefore a form of glioma.[4,5,6,9] The relationship, however, between the histogenesis of GCT and pituicytoma, a distinctive low-grade glioma of the neurohypophysis, remains controversial.[10] Approximately one third of GCTs coexist with pituitary adenomas, and common precursor cells for tumorigenesis have been suggested.[11]
We could not perform stimulation tests in order to diagnose pituitary insufficiency because of the critical illness of our patient, but low basal serum concentrations of anterior pituitary hormones (Table 1) and the significant improvement in general status following the replacement therapy supported the diagnosis of pituitary insufficiency.

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