New Recording

Overview of Immunity

• Immunity Types:

  • Innate Immunity

  • Adaptive Immunity

  • Overlapping functions of Natural Killer (NK) cells and T cells

Innate Immunity

• Definition: Initial defense mechanism, present from birth.

• Components:

  • Physical and Chemical Barriers:

    • Examples: Skin, mucous membranes, saliva, tears

    • Function: Prevent pathogen entry

  • Protective Proteins:

    • Enzymes: Digestive enzymes in saliva and tears that break down pathogens.

    • Complement Proteins:

      • Aid in pathogen elimination during the inflammatory response.

      • Can enhance phagocytosis and attract immune cells to the site of infection.

    • Interferons:

      • Prevent viral replication and spread.

  • Cells:

    • Neutrophils: First responders to injury, attracted to sites of infection.

    • Natural Killer Cells:

      • Attack and destroy infected or cancerous cells.

      • Overlap in function with adaptive immunity (T cells).

Inflammatory Response

• Purpose: Localized response to injury or infection.

• Key Events:

  • Mobilization of body defenses:

    • Increased Blood Flow: Vasodilation draws immune cells to the affected area.

    • Diapedesis: White blood cells (leukocytes) exit circulation to reach tissue.

  • Infection Resolution: Macrophages and T cells are recruited to eliminate pathogens.

  • Tissue Repair: Monocytes cleanup dead cells and debris post-infection.

Adaptive Immunity

• Definition: Specific immune response developed after exposure to pathogens; includes memory cells for faster future responses.

• Components:

  • T Cells:

    • Types: Cytotoxic, helper, regulatory, and memory T cells.

    • Function: Identify and destroy infected cells or help coordinate immune response.

  • B Cells:

    • Produce antibodies specific to pathogens.

    • Antibody Structure: Composed of heavy and light chains, with a variable region for binding antigens.

• Modes of Action:

  • Natural Active Immunity: Immunity gained through natural exposure to pathogens.

  • Natural Passive Immunity: Antibodies transferred from one person to another (e.g., mother to child).

  • Artificial Passive Immunity: Temporary immunity via injected antibodies.

Antigens and Immune Recognition

• Definition: Molecules that trigger an immune response; can be self or non-self.

  • Self Antigens: Present on all body cells, allow immune system recognition of its own cells.

  • Non-Self Antigens: Recognized as foreign; triggers immune response.

• Antigen-Presenting Cells (APCs):

  • Phagocytize foreign antigens and present them on their surface with MHC molecules to T cells.

Response to Infection

• Memory Cells: Generated from T cell divisions; allow for faster response upon subsequent exposures to the same pathogen.

• Antibody Production: Effective against various pathogens; neutralizes and marks them for destruction.

Summary of Immune Response Timing

• Innate Response: Immediate but non-specific (no memory).

• Adaptive Response: Slower initial response, but generates memory (faster subsequent responses).

Conclusion

• Understanding both innate and adaptive immunity is essential for grasping how the body defends itself against infections, highlighting the importance of each component in the overall immune response.