Hormone
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| + | A '''hormone''' (from [[Greek language|Greek]] {{lang|grc|ὁρμή}}, "impetus") is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. 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. All [[multicellular organism]]s produce hormones; [[plant]] hormones are also called [[phytohormone]]s. Hormones in [[animal]]s are often transported in the blood. Cells respond to a hormone when they [[gene expression|express]] a specific [[receptor (biochemistry)|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. | ||
| - | # Any [[substance]], [[produce]]d by one [[tissue]] and [[conveyed]] by the [[bloodstream]] to another to [[effect]] [[physiological]] [[activity]]. | + | [[endocrine system|Endocrine]] hormone [[molecule]]s are secreted (released) directly into the [[bloodstream]], whereas [[exocrine gland|exocrine hormones]] (or ectohormones) are secreted directly into a duct, and, from the duct, they flow either into the bloodstream or from cell to cell by [[diffusion]] in a process known as [[paracrine signalling]]. |
| - | # A [[synthetic]] compound with the same activity. | + | |
| - | # Any similar substance in [[plant]]s. | + | Recently it has been found that a variety of [[exogenous]] [[xenoestrogen|modern chemical compounds]] have hormone-like effects on both humans and wildlife. Their [[Endocrine disruptor|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 [[endogenous|endogenously]] produced hormones do. |
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| + | == Important human hormones == | ||
| + | ''See: [[List of human hormones]]'' | ||
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| + | == See also == | ||
| + | <div style="-moz-column-count:3; column-count:3;"> | ||
| + | * [[Endocrinology]] | ||
| + | * [[Endocrine system]] | ||
| + | * [[Neuroendocrinology]] | ||
| + | * [[Plant hormones]] or [[plant growth regulators]] | ||
| + | * [[Autocrine signaling]] | ||
| + | * [[Paracrine signaling]] | ||
| + | * [[Intracrine]] | ||
| + | * [[Cytokine]] | ||
| + | * [[Growth factor]] | ||
| + | * [[Hormone disruptor]] | ||
| + | * [[Sexual motivation and hormones]] | ||
| + | </div> | ||
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Revision as of 11:50, 16 June 2012
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A hormone (from Greek Template:Lang, "impetus") is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. 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. 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, whereas exocrine hormones (or ectohormones) are secreted directly into a duct, and, from the duct, they flow either into the bloodstream or from cell to cell by diffusion in a process known as paracrine signalling.
Recently it has been found that a variety of exogenous modern chemical compounds 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 do.
Important human hormones
See also
