Untitled Flashcards Set

Innate vs. Adaptive Immunity

• Innate Immunity

  • Non-specific defense mechanisms

  • Immediate response to pathogens

  • Components include physical barriers, chemical barriers, and cellular barriers.

• Adaptive Immunity

  • Specific immune response tailored to specific pathogens

  • Slower response (days to weeks upon first exposure)

  • Involves memory cells for faster response in future exposures.

Barriers Associated with Innate Immunity

• Physical Barriers

  • Skin and mucous membranes that physically block pathogens.

• Chemical Barriers

  • Enzymes in saliva, tears, and sweat; acid in stomach; antimicrobial peptides.

• Cellular Barriers

  • Phagocytes (e.g., macrophages and neutrophils) and natural killer (NK) cells that destroy invaders.

Characteristics of Inflammatory Response

• Symptoms: Redness, heat, swelling, pain.

• Causes: Increased blood flow to the area, accumulation of immune cells, and the release of inflammatory mediators such as histamine and cytokines.

Role of Interferons

• Interferons

  • Proteins released by virus-infected cells that warn neighboring cells.

  • They help protect against viral infections by inhibiting viral replication and activating immune cells.

Main Cells in Adaptive Immune Response

• B Cells

  • Produce antibodies.

• T Helper Cells (CD4+)

  • Activate B cells and other immune cells.

• Cytotoxic T Cells (CD8+)

  • Kill infected or cancerous cells.

Structure of an Antibody

• An antibody consists of:

  • Two heavy chains and two light chains (Y-shaped structure)

  • Five classes of antibodies: IgG, IgA, IgM, IgE, IgD.

Mechanisms by which Antibodies Battle Foreign Invaders

1. Neutralization: Antibodies block pathogen binding to cells.

2. Opsonization: Antibodies tag pathogens for destruction by phagocytes.

3. Complement Activation: Antibodies trigger the complement cascade, leading to pathogen lysis.

4. Agglutination: Antibodies clump pathogens together for easier clearance.

Education Process for T Cells

• Positive Selection: T cells that recognize self-MHC molecules are selected for survival.

• Negative Selection: T cells that bind too strongly to self-antigens are eliminated to prevent autoimmunity.

Activation of T Cells

• T cells are activated when their T cell receptor (TCR) binds to an antigen presented by an MHC molecule on an APC, alongside co-stimulatory signals.

MHC Molecules

• MHC (Major Histocompatibility Complex): Molecules present antigens to T cells.

• MHC I: Presents to cytotoxic T cells (CD8+), found on all nucleated cells.

• MHC II: Presents to helper T cells (CD4+), found on professional antigen-presenting cells (APCs).

Roles of T Helper and Cytotoxic T Lymphocytes

• T Helper Cells

  • Activate other immune cells (B cells, cytotoxic T cells) and coordinate immune response.

• Cytotoxic T Lymphocytes

  • Directly kill infected or cancerous cells.