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Allostasis occurs at the cellular and systems levels. When humans are chronically stressed, the brain chronically raises blood pressure; then arterial muscles predict higher pressure and respond with hypertrophy (like skeletal muscles when we lift weights). Gradually the whole cardiovascular system adapts to life at an elevated pressure level.
An effector is the target acted on, to bring about the change back to the normal state. At the cellular level, effectors include nuclear receptors that bring about changes in gene expression through up-regulation or down-regulation and act in negative feedback mechanisms. An example of this is in the control of bile acids in the liver. [4]
Acid–base homeostasis is the homeostatic regulation of the pH of the body's extracellular fluid (ECF). [1] The proper balance between the acids and bases (i.e. the pH) in the ECF is crucial for the normal physiology of the body—and for cellular metabolism. [1]
Lasting from ten's of years to thousand or more years, these changes are slow enough to allow species to migrate to more optimal environments. Consequently due to habitat tracking, there are some changes in lower levels of hierarchy, but overall, species prevails and stasis is upheld. Fourth Level: Regional disturbances.
The lower the stress levels are in the body, the less likely the allostatic load model will have a significant effect on the brain and health. Although, an increase in stress levels results in an increase in stress on the brain and the health of individuals, making it more likely for the body to have significant effects on homeostasis and cause ...
Enantiostasis is not a form of classical homeostasis, meaning "standing at a similar level," which focuses on maintenance of internal body conditions such as pH, oxygen levels, and ion concentrations. Rather than maintaining homeostatic (stable ideal) conditions, enantiostasis involves maintaining only functionality in spite of external ...
According to Michael Benton, "it seems clear then that stasis is common, and that had not been predicted from modern genetic studies." [17] A paramount example of evolutionary stasis is the fern Osmunda claytoniana. Based on paleontological evidence it has remained unchanged, even at the level of fossilized nuclei and chromosomes, for at least ...
Stasis (from Greek στάσις "a standing still") may refer to: A state in stability theory , in which all forces are equal and opposing, therefore they cancel out each other Stasis (political history) , a period of civil war within an ancient Greek city-state