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For example, endogenous substances, and endogenous processes are those that originate within a living system (e.g. an organism or a cell). For instance, estradiol is an endogenous estrogen hormone produced within the body, whereas ethinylestradiol is an exogenous synthetic estrogen, commonly used in birth control pills.
Bacterial flora is endogenous bacteria, which is defined as bacteria that naturally reside in a closed system. [6] Disease can occur when microbes included in normal bacteria flora enter a sterile area of the body such as the brain or muscle. [6] This is considered an endogenous infection.
An exogenous contrast agent, in medical imaging for example, is a liquid injected into the patient intravenously that enhances visibility of a pathology, such as a tumor.An exogenous factor is any material that is present and active in an individual organism or living cell but that originated outside that organism, as opposed to an endogenous factor.
Endogenous processes such as volcanoes, earthquakes, and tectonic uplift can expose continental crust to the exogenous processes of weathering, erosion, and mass wasting. The effects of denudation have been recorded for millennia but the mechanics behind it have been debated for the past 200 years [ when? ] and have only begun to be understood ...
This process involves two distinct pathways for processing of antigens from an organism's own (self) proteins or intracellular pathogens (e.g. viruses), or from phagocytosed pathogens (e.g. bacteria); subsequent presentation of these antigens on class I or class II major histocompatibility complex (MHC) molecules is dependent on which pathway ...
Pressures can also be sub-categorized as endogenic managed pressures, when they stem from within the system and can be controlled (e.g.: land claim, power generation), and as exogenic unmanaged pressures, when they stem from outside the system and cannot be controlled (e.g.: climate change, geomorphic activities). [9]
All physical and chemical systems in the universe follow the second law of thermodynamics and proceed in a downhill, i.e., exergonic, direction.Thus, left to itself, any physical or chemical system will proceed, according to the second law of thermodynamics, in a direction that tends to lower the free energy of the system, and thus to expend energy in the form of work.
Transfection is the process of introducing exogenous DNA into eukaryotic cells. [12] It is a more specific term for animal cells, as the process of carcinogenesis in these cells is also included in the definition of transformation. Typically, transfection describes the changes in a cell's genome due to the introduction of foreign DNA. [4]