Anatomy and Physiology: The Final Conflict

Introduction

• Focus on the body's final defense mechanism: the cellular immune response.
• Cellular immunity is critical when other immunity mechanisms fail, targeting cells infected by viruses, bacteria, or cancerous cells.

Overview of Immune System Components

• Physical Barriers: Skin and mucous membranes.
• Humoral Immune Response: Antibodies in interstitial spaces.
• Cell-Mediated Response: T lymphocytes (T cells) are the primary actors.

Role of T Cells

• T Cells: Known as T lymphocytes, attack cells hijacked by pathogens or cancerous cells.
• Cause inflammation, activate macrophages, regulate immune response.

Immune System Failures

• Consequences of immune system failure or rogue action, which can lead to self-attacking diseases.
• Immune cells can act destructively like "Mad Max war boys".

Antigen Presentation

• Professional Antigen Presenting Cells: Display pathogen fragments using major histocompatibility complexes (MHCs).
  • MHCs: Proteins that display fragments of pathogens.
  • Classes of MHCs:
    • MHC Class 1: Present in all nucleated cells, signals health status (endogenous proteins).
    • MHC Class 2: On immune-related cells, presents exogenous antigen fragments.

Types of T Cells

• Helper T Cells: Activate immune responses; do not kill but coordinate attack.
  • Recognize antigen-MHC Class 2 combinations.
  • Release cytokines to activate other immune cells.
• Cytotoxic T Cells: Directly kill infected cells by triggering apoptosis.
• Regulatory T Cells: Release inhibiting cytokines to prevent overactive immune response.

Activation Process

• Helper T Cells: Bind to specific antigen-MHC Class 2, activate through cytokines.
• B Cells: Need cytokine confirmation from helper T cells to fully activate.
• Cytotoxic T Cells: Seek out infected cells for destruction.

Importance of Balance

• Immune system's efficiency relies on balance.
• Risks of autoimmune diseases if balance is lost:
  • Multiple Sclerosis: Attacks myelin sheaths.
  • Type One Diabetes: Damages insulin-producing cells.

Conclusion

• The immune system is crucial for survival.
• It is essential to maintain the balance of the immune response to protect the body effectively.

Acknowledgments

• Thanks to contributors like Linnea Boyev and others who make educational content possible.
• Encouragement for support via platforms like Patreon to continue educational projects.