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Created page with 'File:lighterstill.jpgright|frame A '''hormone''' (from Greek ὁρμή - "impetus") is a chemical released by one or more cells that affects ce...'
[[File:lighterstill.jpg]][[File:Hormone_2.jpg|right|frame]]
A '''hormone''' (from Greek ὁρμή - "impetus") is a [[chemical]] released by one or more cells that affects cells in other parts of the [[organism]]. Only a small amount of hormone is required to alter cell [http://en.wikipedia.org/wiki/Metabolism metabolism]. It is essentially a chemical messenger that transports a signal from one [[cell]] to another. All multicellular organisms produce hormones; plant hormones are also called [http://en.wikipedia.org/wiki/Phytohormone phytohormones]. Hormones in [[animal]]s 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.
[http://en.wikipedia.org/wiki/Endocrine_system Endocrine] hormone [[molecules]] are secreted (released) directly into the bloodstream, while [http://en.wikipedia.org/wiki/Exocrine_gland exocrine hormones] (or ectohormones) are secreted directly into a duct, and from the duct they either [[flow]] into the bloodstream or they flow from cell to cell by diffusion in a [[process]] known as [http://en.wikipedia.org/wiki/Paracrine_signalling paracrine signalling].[http://en.wikipedia.org/wiki/Hormones]
[[Category: Chemistry]]
[[Category: General Reference]]
A '''hormone''' (from Greek ὁρμή - "impetus") is a [[chemical]] released by one or more cells that affects cells in other parts of the [[organism]]. Only a small amount of hormone is required to alter cell [http://en.wikipedia.org/wiki/Metabolism metabolism]. It is essentially a chemical messenger that transports a signal from one [[cell]] to another. All multicellular organisms produce hormones; plant hormones are also called [http://en.wikipedia.org/wiki/Phytohormone phytohormones]. Hormones in [[animal]]s 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.
[http://en.wikipedia.org/wiki/Endocrine_system Endocrine] hormone [[molecules]] are secreted (released) directly into the bloodstream, while [http://en.wikipedia.org/wiki/Exocrine_gland exocrine hormones] (or ectohormones) are secreted directly into a duct, and from the duct they either [[flow]] into the bloodstream or they flow from cell to cell by diffusion in a [[process]] known as [http://en.wikipedia.org/wiki/Paracrine_signalling paracrine signalling].[http://en.wikipedia.org/wiki/Hormones]
[[Category: Chemistry]]
[[Category: General Reference]]