Immune Response Notes

Immune Response Overview

  • The immune response can be categorized into two major types: innate immunity (nonspecific) and adaptive immunity (specific).

Innate Immunity

  • Definition: The body's first natural defense against intruders.
  • Characteristics: Nonspecific, does not differentiate between pathogens.
  • Components:
    • Skin: Largest organ, acts as a physical barrier.
    • Mucus Membranes: Line respiratory pathways and trap pathogens.
    • Tears: Contain lysozyme, an enzyme that destroys bacteria.
    • Hair: Includes eyelashes and body hair, sweep away debris.
  • Mechanisms:
    • Phagocytosis: Innate immune cells engulf and digest pathogens.
    • Chemical Barriers: Includes enzymes in tears, saliva, and stomach acid that kill invading microbes.

Adaptive Immunity

  • Definition: Acquired immunity that develops after exposure to pathogens.
  • Characteristics: Specific to particular pathogens, has memory for future encounters.
  • Mechanisms:
    • Vaccination: Introduces a harmless part of a pathogen (e.g., a protein) to stimulate antibody production without causing disease.
    • Antigen Presentation: Specialized cells present antigens to T cells, activating a targeted immune response.

Immune Cells

  • White Blood Cells (WBCs) or Leukocytes: Major players in the immune system.
    • Neutrophils: Most abundant WBC (60-65%); primary phagocytes that respond to infections.
    • Macrophages: Large phagocytic cells that can clean up cellular debris and kill infected cells.
    • Natural Killer (NK) Cells: Identify and kill infected or cancerous cells.
    • T Lymphocytes: Includes Helper T cells, which coordinate immune responses, and Cytotoxic T cells, which directly kill infected cells.
    • B Lymphocytes: Produce antibodies specific to antigens; generate memory cells for faster future response.

Immune Response Phases

  • Innate Response: Immediate and nonspecific; provides rapid defense.
  • Adaptive Response: Takes longer (days) but is more effective; involves memory cells that provide long-term immunity.

Cytokines and Inflammation

  • Cytokines: Chemical signals released by cells to communicate and coordinate the immune response.
  • Histamine: Released by mast cells, contributes to inflammation by increasing blood flow to areas of injury or infection, leading to swelling and redness.

Antigens and Antibodies

  • Antigens: Molecules found on pathogens; trigger immune responses.
  • Antibodies: Proteins produced by B cells in response to specific antigens; bind to antigens to neutralize or mark them for destruction.

Autoimmune Diseases

  • Definition: Conditions where the immune system attacks the body's own tissues. Example includes rheumatoid arthritis, lupus.
  • Causes: Failure of the immune system to recognize self from non-self due to changes in Major Histocompatibility Complex (MHC).

Study Tips

  1. Flashcards: For different immune cells and their functions.
  2. Tree Diagrams: To categorize WBCs and their roles in innate and adaptive immunity.