endógenous

Endogenous refers to something that originates or is produced from within a system, organism, or cell. It is the opposite of exogenous, which describes something originating from outside. In biology, endogenous substances are those produced by the body itself, such as hormones, enzymes, or neurotransmitters. For example, insulin is an endogenous hormone produced by the pancreas to regulate blood sugar levels. Similarly, endogenous repair mechanisms are the body's natural processes for healing damaged tissues.

The concept of endogenous applies to various scientific fields. In medicine, endogenous causes of disease are those arising from internal factors, as opposed to external agents like viruses or toxins. For instance, autoimmune diseases are often considered endogenous because the body's immune system mistakenly attacks its own tissues. In economics, endogenous variables are those determined by the model itself, while exogenous variables are determined by factors outside the model. In astronomy, an endogenous process is one that occurs within a celestial body, such as the internal geological activity of a planet. Understanding whether something is endogenous or exogenous is crucial for diagnosing conditions, developing treatments, and analyzing complex systems.