Lecture Notes: Homeostasis and Feedback Mechanisms

Overview of Course Content

• Previously covered topics: Respiration and Photosynthesis
• Upcoming chapters:
  • Chapter 14: Homeostasis
    • Thermoregulation
    • Regulation of blood glucose concentration
    • Plant hormones
  • Chapter 15: Control and Coordination
    • Nervous system
    • Muscular system
    • Menstrual cycle
    • Plant hormones

Chapter 14: Homeostasis

Introduction to Homeostasis

• Definition: Maintenance of a constant internal environment
  • Involves keeping internal conditions like temperature, pH, and glucose concentrations stable
  • Set points: Narrow limits within which the body maintains these conditions (e.g., body temperature at 37°C)

Importance of Homeostasis

• Ensures optimal functioning of cells and internal environment
• Maintained through mechanisms such as negative feedback

Components of Negative Feedback Mechanism

• Stimulus: Internal or external change from the set point
• Receptor: Detects the stimulus
• Coordinating Center: Receives message from receptor and determines response
• Effector: Carries out corrective actions
• Response: Counteracts the stimulus to restore the set point

Negative Feedback Mechanism

• Continuous monitoring and corrective actions to maintain the internal environment
• Causes fluctuations around the set point
• Example: Body temperature regulation
  • Stimulus (e.g., decrease in body temperature)
  • Response (e.g., increase in body temperature)

Positive Feedback

• Definition: Response reinforces the stimulus
• Not typically used to maintain homeostasis
• Examples:
  • Labor pains: Pain intensity increases progressively
  • Ripening fruit: Fruit becomes progressively riper
  • CO2 inhalation: Increased CO2 leads to even more CO2 inhalation

Comparison of Feedback Mechanisms

• Negative Feedback:
  • Maintains homeostasis
  • Response counteracts stimulus
  • Fluctuates around set point
• Positive Feedback:
  • Amplifies stimulus
  • Less common
  • Results in exponential change

Conclusion

• Negative feedback is crucial for homeostasis.
• Positive feedback occurs in specific scenarios and leads to amplification of the original stimulus.