KS

New Recording

Overview of Immunity

  • Immunity is divided into innate immunity and adaptive immunity.

  • Innate immunity provides a first line of defense against pathogens without memory.

  • Adaptive immunity involves specific responses and has memory, allowing for a faster response during subsequent exposures.

Components of Innate Immunity

1. Physical and Chemical Barriers

  • Skin and mucous membranes act as physical barriers to prevent pathogen entry.

  • Chemical barriers include enzymes in saliva, tears, and other secretions that break down pathogens.

  • Cilia in the respiratory tract trap pathogens, helping to expel them before they enter the lungs.

2. Protective Proteins

  • Complement proteins: aid in the initial response to pathogens through opsonization and lysis.

  • Interferons: proteins released by infected cells that prevent the spread of pathogens to neighboring cells.

3. Immune Cells

  • Natural Killer (NK) Cells: part of innate immunity that can also interact with cells involved in adaptive immunity (e.g., T cells).

  • Neutrophils: first responders that emerge from circulation to the site of tissue injury to combat infection, particularly against bacteria.

  • Macrophages and T lymphocytes: also involved in inflammation and pathogens capture.

4. Inflammatory Response

  • Initiation: Triggered by tissue damage causing redness, heat, swelling, and pain.

  • Mobilization of Body Defenses: Increased blood flow (vasodilation) brings more immune cells to the site.

  • Clean Up and Repair: Monocytes migrate to clean up damaged tissue post-infection.

Components of Adaptive Immunity

1. T Cells

  • Types of T Cells:

    • Cytotoxic T Cells: kill infected or cancerous cells directly.

    • Helper T Cells: enhance the immune response by activating other immune cells.

    • Regulatory T Cells: moderate immune responses to prevent overactivity.

    • Memory T Cells: remain in circulation for faster response upon re-exposure to the same antigen.

2. B Cells

  • Produce antibodies that target specific pathogens.

  • Different antibody classes (e.g., IgA, IgE) have specific functions in immune response.

  • Antigen Presentation: B cells can present antigens to T cells for more effective immune response activation.

3. Modes of Action

  • Neutralization: Antibodies bind to pathogens to prevent their function.

  • Opsonization: Marking pathogens for destruction by phagocytes.

  • Agglutination: Clumping pathogens together to enhance phagocytosis.

Role of Antigens

  • Antigens are substances that trigger an immune response, identified by immune cells via Major Histocompatibility Complex (MHC).

  • Self-antigens: recognized as part of the body; foreign antigens trigger immune attacks.

Key Differences Between Innate and Adaptive Immunity

  • Innate Immunity: Fast acting, non-specific, no memory, involves barriers and immediate cellular responses (e.g., phagocytes).

  • Adaptive Immunity: Slow to develop initially, specific to pathogens, has memory, involves T and B cells.

Inflammatory Response Mechanism

  1. Injury and Pathogen Entry: Introduces bacteria to tissue; inflammation begins.

  2. Vasodilation: Increases blood flow to the site to deliver immune cells.

  3. Leukocyte Mobilization: Neutrophils and other leukocytes migrate through capillary gaps to reach the infection site.

  4. Tissue Repair: Monocytes transition to macrophages to clean debris and regenerate tissue.