Homeostasis is the tendency for an organism or cell to maintain a constant internal environment within tolerance limits
Internal equilibrium is maintained by adjusting physiological processes, including:
- Body temperature (normally between 36 – 38ºC)
- Carbon dioxide concentration (normally 35 – 45 mmHg)
- Blood pH (normally between 7.35 – 7.45)
- Blood glucose levels (normally 75 – 95 mg/dL)
- Water balance (varies depending on individual body size)
Homeostatic mechanisms operate via a feedback loop that may involve either the nervous or endocrine systems (or both)
- When specialised receptors detect an internal change to conditions, a response is generated to correct the change
- Most homeostatic responses involve an effect that is antagonistic to the detected stimulus (negative feedback)
- When levels return to equilibrium, the effector ceases to generate a response and an internal balance is therefore maintained
- If a physiological condition moves outside of tolerance limits, disease will occur as a consequence
Homeostasis
