Anatomy and Physiology - Immune System Final Lecture
Overview
- Focus on the body's last line of defense: the cell-mediated or cellular immune response.
- Role of T lymphocytes (T cells) in fighting cells hijacked by pathogens or become cancerous.
Immune System Functions
- Skin and Mucous Membranes: Physical barriers against infection.
- Humoral Immune Response: Antibodies to keep interstitial spaces healthy.
- Cell-Mediated Immune Response: Activated when pathogens breach cellular defenses.
T Cells
- Types: Helper T cells, Cytotoxic T cells, Regulatory T cells.
- Functions:
- Helper T Cells: Activate other immune cells, including cytotoxic cells.
- Cytotoxic T Cells: Destroy infected or cancerous cells.
- Regulatory T Cells: Prevent an overactive immune response.
Major Histocompatibility Complex (MHC)
- MHC Class 1:
- Present in all nucleated cells.
- Displays endogenous proteins, alerts immune cells if abnormal.
- MHC Class 2:
- Found on professional antigen-presenting cells (e.g., macrophages, B cells).
- Displays fragments of exogenous antigens.
Immune Response Process
- Pathogen Encounter: Phagocytes engulf and display pathogen fragments via MHC.
- T Cell Activation: Helper T cells bond to specific MHC-antigen complexes, activate.
- Cytokine Release: Helper T cells release cytokines to amplify immune response.
- Cytotoxic T Cells: Bind to infected cells showing abnormal proteins and induce apoptosis.
Implications of Immune System Failure
- Without T Cells:
- No adaptive immune response.
- HIV/AIDS targets Helper T cells, crippling the immune response.
- Hyperactive Immune System: Can cause autoimmune diseases.
Autoimmune Diseases
- Example: Multiple sclerosis, Type One Diabetes.
- Result from immune system attacking the body's own tissues.
Conclusion
- Immune system's role in protecting the body while maintaining balance.
- Regulation critical to prevent self-damage.
Acknowledgments
- Contributions by various individuals and the Crash Course team.
Remember, the immune system is both a resilient and fragile network, vital for survival. This lecture emphasized the complexity and importance of immune regulation.