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