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Showing 91–120 of 1709 reference entries

ChemistryReaction rates and empirical rate laws

Reaction rate measures change over time; a rate law describes its dependence under specified conditions.

MethodChemistryCatalysis and equilibrium

A catalyst changes the reaction pathway and rate, while preserving the equilibrium constant for the same reaction.

ModelBiologyCells as units of life

Cell theory describes the organization and reproduction of cellular life.

ModelBiologyDNA and sequence information

DNA's base sequence stores biological information.

DefinitionBiologyGene expression

Gene expression produces functional RNA or protein from gene information.

DefinitionBiologyDNA replication

Complementary base pairing allows DNA strands to serve as copying templates.

ModelBiologyCell cycle, mitosis and cytokinesis

DNA duplication, nuclear division and cytoplasmic division are distinct events in a typical mitotic cycle.

ModelBiologyMeiosis and chromosome segregation

Typical diploid meiosis halves the number of chromosome sets through two divisions after one DNA replication.

ModelBiologyAlleles and Mendelian segregation

A diploid individual's paired alleles can segregate into gametes.

ModelBiologyBiological evolution

Evolution concerns inherited change across generations.

DefinitionBiologyNatural selection

Heritable variation can change through differences in reproductive contribution.

ModelBiologyGenetic drift

Chance can change allele frequencies independently of an adaptive advantage.

ModelBiologyCommon ancestry and branching lineages

Evolutionary relationships describe descent from shared ancestors.

ModelBiology · ChemistryMetabolism and chemical pathways

Metabolism comprises the regulated chemical reactions of living systems.

DefinitionBiologyOxygenic photosynthesis

Oxygenic photosynthesis couples light-energy capture to carbon fixation and releases oxygen from water.

ModelBiologyAerobic cellular respiration

Aerobic respiration couples nutrient oxidation to ATP production, using oxygen as the final electron acceptor.

ModelBiologyMembranes and transport

Selective membranes and transport proteins regulate movement between a cell and its surroundings.

ModelBiologyEcology and ecosystems

Ecology examines organisms' interactions with one another and their physical environment.

DefinitionBiologyHomeostasis and negative feedback

Feedback can maintain internal variables within functional ranges.

ModelEarth & cosmosRock cycle and geological transformation

Rock materials can change through multiple geological pathways.

ModelEarth & cosmosPlate tectonics

Moving lithospheric plates organize many large-scale geological processes.

ModelEarth & cosmosEarth's water cycle

Water moves among reservoirs above, on and below Earth's surface.

ModelEarth & cosmos · Biology · ChemistryEarth's carbon cycle

Carbon moves through biological, oceanic, atmospheric and geological reservoirs.

ModelEarth & cosmosPlanetary radiative energy balance

Earth's energy storage changes when incoming and outgoing energy differ.

ModelEarth & cosmosAtmospheric greenhouse effect

Infrared absorption and emission affect how Earth loses heat to space.

ModelEarth & cosmosWeather, climate and their time scales

Weather describes short-term conditions; climate describes their longer-term patterns.

DefinitionEarth & cosmosOrbits as gravitational motion

An orbiting body can remain in continuous gravitational free fall.

ModelEarth & cosmosStellar fusion and evolution

Main-sequence stars release energy by fusing hydrogen into helium.

ModelEarth & cosmosHot Big Bang and the cosmic microwave background

Expansion and relic radiation support an earlier hot, dense Universe.

ModelMathematics & logicFirst-order predicates and quantifiers

Quantifiers bind variables over a specified domain.

Definition
ModelSource checked

Homeostasis and negative feedback

Biology

Feedback can maintain internal variables within functional ranges.

Key knowledge

Homeostasis is active regulation that keeps internal conditions within functional ranges despite changes. In negative feedback, a response opposes the detected deviation, as in regulated animal temperature or blood-glucose control.

Conditions and scope

  • Maintained ranges depend on organism and circumstances; they are not perfectly constant values.
  • A regulated living system is not necessarily at thermodynamic equilibrium, and regulation can fail.
Sources · 2

References

Sources retain their recorded scope. A source link alone does not establish verification of every statement.

  1. Biology 2e, 33.3 Heat Conservation/Dissipation and Neural ThermoregulationMary Ann Clark, Matthew Douglas and Jung Choi — OpenStax, Rice UniversityTextbook chapteropenstax.orgRead source
  2. Migration: Introduction to homeostasisThe Open UniversityCourse notesopen.eduRead source

Evidence and review

Published animal-regulation and negative-feedback examples; no physiological test was performed.

2026-10-10 · English dynamic-range and feedback meaning checked against section 33.3; diagnostic thresholds and treatment are outside scope.

Foundational review

2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.

Sources from other places

Agreement within this scope

Internal regulation and temperature-restoring negative feedback.

Regulation maintains useful ranges, not a perfectly constant state.

Related reference entries

Explore relationships within this area of study and its connections to other areas.

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Scientific relationships · 1 / 1

The relationship type describes the connection. Its linked statements, sources and conditions define the scope.

  1. Related to
    Relationship sources · 1

    Linked statements

    • In the vertebrate thyroid-axis example, hypothalamic signals stimulate pituitary hormone release, which stimulates the thyroid. Rising thyroid-hormone concentrations inhibit upstream stimulation. Neural and blood-chemical signals can also trigger endocrine secretion, so endocrine control is a connected feedback system rather than a hormone acting in isolation.

    Feedback contributes to regulated internal conditions.

Entry detailsPermanent link to this entry ↗
Record identity
bio-homeostasis
Revision
core.1
Structured reference record
Essential core · first collection