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'''Endogenous''' substances and processes are those that originate from within a system such as an [[organism]], [[Tissue (biology)|tissue]], or [[Cell (biology)|cell]].<ref>{{cite web|url=http://dictionary.reference.com/search?q=endogenous |title=Endogenous | Define Endogenous at Dictionary.com |publisher=Dictionary.reference.com |date= |accessdate=2011-07-11}}</ref> The term is chiefly used in biology but also in other fields.<ref group = nb>The term has also been applied to sociological concepts. |
'''Endogenous''' substances and processes are those that originate from within a system such as an [[organism]], [[Tissue (biology)|tissue]], or [[Cell (biology)|cell]].<ref>{{cite web|url=http://dictionary.reference.com/search?q=endogenous |title=Endogenous | Define Endogenous at Dictionary.com |publisher=Dictionary.reference.com |date= |accessdate=2011-07-11}}</ref> The term is chiefly used in biology but also in other fields.<ref group = nb>The term has also been applied to sociological concepts. See (Vasey 2002 p.8). </ref> |
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Endogenous substances and processes contrast with exogenous ones, such as drugs, which originate from outside of the organism. |
Endogenous substances and processes contrast with exogenous ones, such as drugs, which originate from outside of the organism. |
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Endogenous substances and processes are those that originate from within a system such as an organism, tissue, or cell.[1] The term is chiefly used in biology but also in other fields.[nb 1]
Endogenous substances and processes contrast with exogenous ones, such as drugs, which originate from outside of the organism.
Cell signalling systems such as hormone and neurotransmitter systems use endogenous substances. An example is the endogenous cannabinoid system, from which the term "endocannabinoid" derives. The endocannabinoid system is important in physiology but can be modulated by exogenous phytocannabinoids originating from outside the organism, such as THC.[2] An example of an endogenous hormone system is the endogenous steroids.[3]: 261 Endogenous substances can regulate sleep.[4]: 1 Endogenous opioids are peptides, such as enkephalins and endorphins, that can modulate the opioid system.[5] The term "endorphin" is derived from "endogenous morphine". Nitric oxide is an endogenous cell signalling molecule.[6]
Endogenous transcription factors are those manufactured by the cell, as distinguished from cloned transcription factors.[citation needed]Endogenous processes, which include senescence, the menstrual cycle and the self-sustained circadian rhythms of plants and animals.[citation needed]
Endogeneity can, in some biological systems, particularly with viruses and prokaryotes, pertain to DNA incorporated (endogenized) into the organism.[7] However, because of homeostasis[why?], discerning between internal and external influences is often difficult.[citation needed] Endogenous viral elements, which are DNA sequences derived from viruses that are ancestrally inserted into the genomesofgerm cells.[citation needed] These sequences, which may be fragments of viruses or entire viral genomes (proviruses), can persist in the germline, being passed on from one generation to the next as host alleles.[citation needed]
Endogenous biological clocks and biological rhythms originating from endogenous mechanisms allow forms of biochronometry.[8]: 281–282
Endogeny can occur with interactions with environmental influences that change systems.[9]: 8
Orthogenesis is a similar concept to endogeny but refers to changes within separate systems that results in their evolution along similar paths.[9]: 8 The concept of orthogenesis has never been widely favored in evolutionary biology.[9]: 8
Endogeny can refer to changes that originate from within a system [9]: 8 . Endogenous changes can occur in social systems and can be modelled by Marxian dialectics [9]: 8 .