Lecture on Immunity and Immune System Components

Introduction

• Discussion on upcoming test, which is perceived as easier than usual by students.
• Main focus: Innate and adaptive immune system components.

Innate Immunity

Characteristics

• Natural and non-specific.
• Same response to all pathogens.

Components

First Line of Defense

• Barriers: Skin, mucous membranes.
• Chemical Components: Secreted chemicals.

Second Line of Defense

• Cells and Proteins: Neutrophils, basophils, macrophages, toll-like receptors (TLRs).
• Functions:
  • Recognition: TLRs recognize pathogens and trigger responses.
  • Inflammation: Characterized by redness, warmth, swelling, pain, loss of function.
  • Phagocytosis: Neutrophils and macrophages engulf pathogens.
  • Cytokines: Secreted by immune cells to signal other immune activities.
  • Diapodesis and Chemotaxis: Movement of immune cells to infection sites.
• Interferon Response: Proteins released to combat viral infections.
• Complement System:
  • Composed of 26 proteins.
  • Functions: Membrane attack complex (MAC) and opsonization (marking pathogens for destruction).

Adaptive Immunity

Characteristics

• Specific and slower than innate immunity.
• Involves memory formation for long-term protection.

Components

• T Cells and B Cells: Main players.
• Types of Immunity:
  • Active Immunity: Body produces its own antibodies (e.g., vaccination or natural infection).
  • Passive Immunity: Receives pre-formed antibodies (e.g., maternal antibodies, antibody therapy).
  • Natural vs. Artificial:
    • Natural: Acquired through life experiences (e.g., exposure to pathogens in the wild).
    • Artificial: Acquired through medical procedures (e.g., vaccines).

Processes

• Antigen and Epitope: Antigen is a piece of a pathogen; epitope is a specific part of an antigen.
• Lymphocytes:
  • B Cells: Produced in bone marrow, produce antibodies.
  • T Cells: Mature in thymus, include CD4+ (helper T cells) and CD8+ (cytotoxic T cells).
  • CD4+ T Cells: Help activate B cells.
  • CD8+ T Cells: Destroy infected or cancerous cells.

Immunological Memory

• Memory Cells: Remember pathogens for faster response upon re-exposure.
• Antibody Production: Specific to each pathogen.

Review and Conclusion

• Encouragement to study for the test, emphasizing memorization of the immune system components and their functions.
• Reminder of the importance of distinguishing between innate and adaptive immunity and understanding immune system processes and interactions.
• Class dismissed with a call to start reviewing the material thoroughly before the next session.