Definition of endogenous
1 : growing or produced by growth from deep tissue <endogenous plant roots>
2a : caused by factors inside the organism or system <suffered from endogenous depression> <endogenous business cycles>b : produced or synthesized within the organism or system <an endogenous hormone>
Did You Know?
When biologists need to make a distinction between things that are produced within a cell or organ and things that affect it from the outside, they use the terms endogenous and exogenous. It used to be thought, for instance, that mutations in cells always resulted from exogenous causes, until it was discovered that substances in the body, including those called oxidants, could cause them endogenously as well. "Circadian rhythms"—the regular cycles, roughly 24 hours in length, that plants, animals, and humans rely on to regulate their days—are endogenously generated and don't actually depend on the sun for their timing.
First Known Use of endogenous
Medical Definition of endogenous
1: growing from or on the inside <endogenous spores>
2: caused by factors within the body or mind or arising from internal structural or functional causes <endogenous malnutrition> <endogenous psychic depression>
3: relating to or produced by metabolic synthesis in the body <endogenous opioids> <endogenous amino acids>—compare exogenous
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