Immunology is the branch of biology and medicine that studies the immune system—the body's defense system against infections, diseases, and foreign substances. 🛡️ Key Concepts: Immune System: A complex network of cells, tissues, and organs that protect the body from harmful invaders like bacteria, viruses, fungi, and parasites. Immunologist: A scientist or doctor who studies or treats immune system disorders. 🧬 Two Main Types of Immunity: Innate Immunity (nonspecific): Your first line of defense Includes physical barriers (skin, mucus), immune cells (e.g., neutrophils), and inflammation Responds quickly but not specifically Adaptive Immunity (specific): Learns and remembers past invaders (via memory cells) Involves T cells and B cells Produces antibodies to neutralize pathogens 💉 Applications of Immunology: Vaccines: Train the immune system to recognize and fight pathogens Autoimmune diseases: When the immune system mistakenly attacks the body (e.g., lupus, rheumatoid arthritis) Immunodeficiencies: Weak or missing immune responses (e.g., HIV/AIDS) Allergies: Overreaction to harmless substances Cancer immunotherapy: Using the immune system to fight cancer