Anatomy and Physiology: The Cellular Immune Response

Jun 30, 2024

Anatomy and Physiology: The Cellular Immune Response

Introduction

  • Final Lecture: Focus on the body's last line of defense.
  • Context: When skin, mucous membranes, and humoral immune responses fail.

Cellular Immune Response

  • Key Players: T lymphocytes (T cells)
  • Functions of T cells:
    • Cause inflammation
    • Activate macrophages
    • Regulate immune response

Dangers of Immune Failure

  • Two Critical Risks:
    • Body fails to defend itself
    • Immune system attacks healthy cells
  • Aggressiveness: Immune cells act like 'biological versions of Mad Max war boys.'

Antigen Presentation

  • Major Histocompatibility Complexes (MHCs):
    • Class 1 MHC: Present in all nucleated cells, signaling internal health.
    • Class 2 MHC: Present in professional antigen-presenting cells (APCs).
  • APCs: Phagocytes that engulf pathogens and display fragments (antigens)
  • Purpose: Show antigens to T cells for recognition and activation

Types of T Cells

  • Helper T Cells:
    • Activate other immune cells
    • Produce cytokines to boost immune response
  • Cytotoxic T cells:
    • Kill infected/damaged cells
    • Use enzymes to induce apoptosis (cell death)
  • Regulatory T cells:
    • Release cytokines to inhibit immune response after threat is handled
    • Prevent autoimmune reactions, maintaining balance

Mechanism of T Cell Activation

  • Helper T Cells:
    • Activated when binding to specific antigen-MHC combination
    • Trigger immune response through cytokine release
  • Cytotoxic T Cells:
    • Bind to infected cells displaying antigens on class 1 MHC
    • Release enzymes to kill infected cells

Role in Adaptive Immune Response

  • Helper T Cells:
    • Essential for both humoral and cellular responses
    • Ensure B cells fully activate and produce antibodies
  • Check and Balance:
    • Prevent immune system from attacking self
  • Diseases from Immune Dysfunction:
    • Multiple sclerosis (demyelinates neurons)
    • Type 1 diabetes (destroys insulin-producing pancreatic cells)

Conclusion

  • Key Takeaways:
    • The immune system's precise function is crucial
    • Balance is needed to avoid both infection and autoimmunity
  • Acknowledgements: Thanks to the creators and patrons of Crash Course.
  • Contact: Mentioned patreon.com/crashcourse for support

Credits

  • Writers, editors, consultants, directors, sound designers, and graphics team named

Final Note

  • Critical Learning Points:
    • How T cells operate and are vital to immune defense
    • Importance of cytokines in activating immune responses
    • Risks and mechanisms of autoimmune diseases

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For immune system and other anatomy topics, check Crash Course videos.

[Source: Crash Course Anatomy and Physiology]