Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
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 ?
Pharmaceutical companies have recognized the commercialization and therapeutic potential of peptide hormones for treating various diseases.
For years, people have argued that synthetic hormones and bioidentical hormones are the same.
First, you need to decode your deficiency--which hormones are you really missing?
For all practical purposes, there are three different types of treatment options for hormone balancing: natural, or bio-identical hormones; synthetic hormones; and phyto, or plant hormones.
The hormone that initiates the body's response to stress, CRF, is found throughout the brain.
Understanding the claim that bio-identical hormones are natural (and, by implication, that standard menopause HT hormones aren't) is probably a good place to start.
However, a separate study of black women finds a greater risk of breast cancer in women who took the hormone for 10 or more years than in women who had no hormone therapy.
Lucille explains, "Digestion couldn't happen without the endocrine system, which produces hormones that control the necessary chemical activities.
One limitation of the study is that the hormone was studied only in normal mice, and not in fat ones.
Thyroid hormones were extracted from fathead minnow larvae based on the technique described by Greenblatt et al.
The anabolic steroids involved in the Major League Baseball scandal mimic hormones responsible for controlling female characteristics.
6) Later results also found women taking Prempro had twice the risk of dementia compared to those not using any hormones.