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Related to Hormones: endocrine system, pregnancy hormones



incretions, biologically active substances formed by the endocrine glands and secreted directly into the blood.

The term “hormone” was introduced by the English physiologists W. Bayliss and E. Starling in 1902. Hormones are transported by the blood and influence the activity of organs, modifying physiological and biochemical reactions by activating or inhibiting enzyme processes. There are more than 30 known hormones secreted by the endocrine glands of mammals and man (see Table 1). Hormones do not affect the organs in which they are formed. They are relatively easily destroyed; constant manufacture and secretion are therefore necessary in order to maintain sufficient amounts in the blood. Their principal function is the hormonal regulation of the activities of various organs and systems and of the organism as a whole.

Hormones may be classified according to their chemical nature as steroid hormones, such as those of the adrenal cortex, testes, and ovaries; proteo hormones, such as insulin, growth (somatotropic) hormone, and the gonadotropic hormones (follicle-stimulating, luteinizing, and luteotropic); polypeptide hormones, such as adrenocorticotropic hormone, melanocyte-stimulating hormone, oxytocin, vasopressin, glucagon, and thyrocalcitonin; and amino acid derivatives, such as thyroxine, triiodothyronine, epinephrine, and norepinephrine. Hormones are also found in invertebrates (for example, the hormones of molting and pupation in insects). Plants also have biologically active compounds (for example, auxin, gibberellins, and quinines) that are sometimes called hormones, or phytohormones. Many active compounds (for example, histamine and serotonin) are formed in the tissues of vertebrates that are not in fact hormones, but rather parahormones, or histohormones; these are often grouped with the so-called hormonoids.


References in periodicals archive ?
While the jury is still out on the safety of any hormone therapy, it looks like low doses of bioidentical hormones are safer than traditional synthetic hormones.
I suggest consulting with an experienced anti-aging doctor--such as those in the fellowship program of the American Academy of Anti-Aging--who knows how to test for hormones and interpret the results.
Second, scientists learned that substances traditionally classified as hormones do not have to enter the bloodstream to affect other cells.
When taken up into our bloodstreams, these hormones are very physiologically active substances and have a powerful effect on humans.
Under stress, the brain releases CRF, a hormone, into the bloodstream.
Are bio-identical hormones safer than other forms of HT?
Researchers launched the WHI in part to study the long-term effects of hormone replacement.
Yet even on the far side of this healing adventure, it took me awhile to understand how hormone imbalance, the environment and our inner ecology are inextricably linked--and how I'd unwittingly contributed to my illness.
Although the new hormone, should it prove effective as an appetite suppressant in humans, would be quite useful in our age of obesity, it would never be available in pill form.
The next morning, free and bound hormones were separated by addition of 100 [micro]L Sac-Cel (Immunodiagnostic Systems Limited, Tyne and Wear, UK) and a solution of cellulose-coupled antibodies (anti-sheep/goat); tubes were centrifuged, and the pellet of bound radiolabeled hormone was counted (Cobra gamma counter; Packard, Boston, MA, USA).
This hormone is produced naturally by the bodies of males and, in much smaller amounts, by females.
Sarrel, today's transdermal options provide exceptionally accurate delivery of hormones.