Homeostasis is the mechanism enabling organisms to maintain internal stability amidst external fluctuations. Achieved through feedback systems, it encompasses temperature, fluid balance, blood sugar, and pH regulation. Disruptions in homeostasis can be detrimental, leading to potential diseases or critical conditions.


Homeostasis refers to the process by which living organisms maintain a relatively stable internal environment despite changes in external conditions. It ensures that the body’s internal environment remains consistent and optimal for various cellular processes.

Dynamic Equilibrium

Rather than maintaining absolute constancy, homeostasis involves balancing inputs and outputs to establish a dynamic equilibrium.

Negative Feedback

  • Most common in biological systems.
  • When a system deviates from its target set point, negative feedback mechanisms work to counteract or oppose the deviation.
  • Example: Regulation of body temperature. If it rises, mechanisms work to lower it, and vice versa.

Positive Feedback

  • Less common but vital in certain processes.
  • Instead of opposing deviation, it amplifies it.
  • Example: Blood clotting, where initial clotting triggers more clotting until the wound is sealed.

Components of Homeostatic Systems

  • Receptors: Detect changes from a set point and send this information to a control center.
  • Control Center: Processes the information and determines the appropriate response.
  • Effectors: Carry out the response to restore balance.

Examples of Homeostatic Processes

  • Thermoregulation: Maintenance of internal body temperature.
  • Osmoregulation: Maintenance of salt and water balance.
  • Blood Sugar Regulation: Ensuring glucose levels in the bloodstream are consistent.
  • pH Balance: Maintaining a relatively neutral internal environment.

Importance in Evolution

  • The ability of an organism to maintain homeostasis has evolutionary advantages, allowing it to survive in varying environments.
  • Evolutionary adaptations related to homeostasis include the development of endothermy in mammals and birds.

Homeostasis & Disease

  • Disruptions in homeostasis can lead to disease or can be a result of disease.
  • Example: Diabetes, a condition where the body can’t regulate blood sugar levels effectively.

Connection to Cell Biology

  • At a cellular level, mechanisms like the sodium-potassium pump help maintain electrochemical gradients, a form of homeostasis vital for nerve impulse transmission.
  • The proper function of cellular organelles is dependent on maintaining ionic concentrations, pH, and nutrient levels.

Global Perspective

While homeostasis is primarily discussed in terms of individual organisms, similar concepts apply at larger scales. For instance, ecosystems have checks and balances that work to maintain equilibrium, such as predator-prey relationships.