Hormone - Wikipedia, the free encyclopedia


** Hormone **

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For other uses, see Hormone (disambiguation).
Epinephrine (adrenaline), a catecholamine-type hormone

A *hormone* (from Greek ὁρμή, "impetus") is a chemical
released by a cell, a gland, or an organ in one part of the body that
affects cells in other parts of the organism. Generally, only a small
amount of hormone is required to alter cell metabolism. In essence, it is a
chemical messenger that transports a signal from one cell to another.^[1]
All multicellular organisms produce hormones; plant hormones are also
called phytohormones. Hormones in animals are often transported in the
blood. Cells respond to a hormone when they express a specific receptor for
that hormone. The hormone binds to the receptor protein, resulting in the
activation of a signal transduction mechanism that ultimately leads to cell
type-specific responses.

Endocrine hormone molecules are secreted (released) directly into the
bloodstream, typically into fenestrated capillaries. Hormones with
paracrine function diffuse through the interstitial spaces to nearby target

A variety of exogenous chemical compounds, both natural and synthetic, have
hormone-like effects on both humans and wildlife. Their interference with
the synthesis, secretion, transport, binding, action, or elimination of
natural hormones in the body can change the homeostasis, reproduction,
development, and/or behavior, just as endogenously produced hormones


· 1 Hormones as signals
· 2 Interactions with receptors
· 3 Physiology of hormones
· 4 Effects of hormones

· 4.1 In mammals

· 5 Chemical classes of hormones
· 6 Pharmacology
· 7 Important human hormones
· 8 See also
· 9 References
· 10 External links

*Hormones as signals[edit]*

/See also Signal transduction./

Hormonal signaling involves the following:^[/citation needed/]

1. *Biosynthesis* of a particular hormone in a

Source: en.wikipedia.org/wiki/Hormone

what are hormones

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