Homeostasis

Homeostasis

  • Definition:
    Homeostasis = regulation of internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes.

  • Why it’s needed:

    • Enzymes and cells need stable conditions to function properly.

    • If conditions change too much, enzymes cannot work effectively.

  • Internal conditions controlled by homeostasis:

    • Blood glucose concentration

    • Body temperature

    • Water levels

Automatic Control Systems

  • Purpose: Keep internal conditions constant automatically.

  • Can involve:

    • Nervous system

    • Hormones

Key Features of Automatic Control Systems

  1. Stimulus – change in internal or external environment.

    • Examples: blood glucose concentration, skin temperature.

  2. Receptor – detects stimulus (e.g., receptor cells).

  3. Coordination Centre – processes information and decides on a response.

    • Examples: brain, spinal cord, pancreas.

  4. Effector – carries out the response.

    • Muscles → contract.

    • Glands → secrete hormones.

  5. Response – restores the optimum level.

✅ Key takeaway:
All homeostasis systems follow this model:
Stimulus → Receptor → Coordination Centre → Effector → Response