Coordination And Control: Homeostasis

14.4 Homeostasis

Definition

• Homeostasis = maintenance of a constant internal environment.
• Keeps conditions stable for enzyme activity and cell function.

Control By Negative Feedback

• Change in condition → detected by receptors → corrective mechanism → restores set point.
• Example: blood glucose regulation, body temperature control.

Examples Of Homeostasis

• Body temperature → kept around 37°C.
• Blood glucose concentration → kept constant by insulin and glucagon.
• Water balance → controlled by kidneys.
• CO₂ concentration → controlled by lungs.

Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course

Why It Matters

• Enzymes only work within narrow pH and temperature ranges.
• Prevents harmful build-up (e.g., CO₂, urea).
• Ensures efficient metabolism.

Key Point

• Negative feedback is the main principle of homeostasis:
  • If too high → mechanisms bring it down.
  • If too low → mechanisms bring it up.

Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course