Anatomy and Physiology: The Cellular Immune Response

Introduction

Final lecture on anatomy and physiology.
Focus on the body's last defense - the cellular immune response.
When other defenses fail (skin, mucous membranes, humoral response), the cellular response takes over.

T Cells:
- Known as T lymphocytes or T cells.
- Target body cells hijacked by viruses, bacteria, or cancer.
- Cause inflammation, activate macrophages, regulate immune response.
Risks of Immune System Failure:
- Complete failure to protect or rogue immune system attacks healthy cells.
- Immune cells can be hyperactive, attacking host cells.

Phagocytes: Engulf pathogens, break them into molecules, display fragments on MHC proteins.
Major Histocompatibility Complex (MHC):
- Class 1 MHC: Present in all nucleated cells, show endogenous protein fragments.
- Class 2 MHC: Found in immune-related cells, bind fragments of exogenous antigens.

Made in bone marrow, mature in the thymus.
Types:
- Helper T Cells: Activate other immune cells, raise alarms via cytokines.
- Cytotoxic T Cells: Kill infected cells, release enzymes triggering apoptosis.
- Regulatory T Cells: Release inhibiting cytokines to prevent immune overreaction.
Activation Process:
- Helper T cells activated upon binding to specific MHC-antigen combinations, release cytokines.
- Cytokines help activate cytotoxic T cells and B cells.

Immune system requires checks and balances to avoid autoimmune diseases.
Autoimmune diseases result when the immune system attacks the body's own tissues (e.g., multiple sclerosis, Type 1 Diabetes).

The immune system's role is crucial in defending the body while maintaining balance.
Importance of the interconnected nature of the body’s systems.