Immunity + Hypersensitivity

• hypersensitivity is when the body overreacts to a substance that is normally harmless
• autoimmunity is when normal protective immune response paradoxically turns against or attacks the body, leading to tissue damage
• the immune system consists of the bone marrow and lymphoid tissue
• the bone marrow produces T cells and B cells, which are the main immune cells
• lymphoid tissue includes the spleen and lymph nodes
• lymphocytes specifically recognize and respond to foreign antigens
• dendritic cells are the antigen presenting cells
• b cells are memory cells part of humoral immunity, they remember the antigen
• t cells are memory cells part of cell mediated immunity
• The 3 types of T cells are cytotoxic-killer, helper, and suppressor
• WBCs aka leukocytes include neutrophils, eosinophils, basophils, lymphocytes, monocytes, and macrophages
• neutrophils kill bacteria, fungi, and foreign debris
• monocytes clean up dmged cells
• eosinophils kill parasites + cancer cells, and are involved in the allergic response
• lymphocytes help fight viruses and make antibodies
• basophils are involved in the allergic response
• natural/innate immunity is the body's first line of defense
• innate immunity includes epithelial barriers, phagocytic cells, and NK cells
• the inflammatory response is the major function of the natural immune system and the response to invading organisms or tissue injury
• the chemical mediators are histamine, bradykinin, and prostaglandins
• Acquired/adaptive immunity is the body's second line of defense and involves being able to recognize and react to a large number or microbes and non-microbial substances
• active immunity lasts many years and involves defenses developed by a person's own body
• passive immunity is temporary and results from a transfer of a source outside of the body
• antigens are substances foreign to the host that can stimulate an immune response
• antibodies recognize antigens on the surface of pathogens and destroy them
• the most common immunoglobins in infection is IgG and IgM
• IgG appears in interstitial fluid and assumes a major role in bloodborne and tissue infections
• IgA appears in body fluid and protects against respiratory, GI, and GU infections
• IgM appears in intravascular serum and responds to bacterial and viral infections
• IgD appears in small amounts in serum and influences B lymphocyte differentiation
• IgE appears in serum and plays a role in allergic and hypersensitivity reactions and protects against parasitic infections
• Complement system has 3 functions:

  • defend the body against bacterial infection
  • bridge natural and acquired immunity
  • dispose of immune complexes and the by-products
• WBCs ingest foreign particles and destroy invading agents
• apoptosis: the death of cells which occurs as a normal and controlled part of an organism's growth or development
• humoral or antibody response- B lymphocytes
• cellular immune response- T lymphocytes
• B lymphocytes respond to antigens by triggering antibody formation
• agglutination- clumping of red blood cells due to antibodies
• opsonization- process of recognizing and targeting invading particles for phagocytosis
• antigen-antibody binding is a reversible process, where the antibody binds to the antigen and the antigen binds to the antibody