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.