BIOL 210 Immune Response S24 PDF

Non-specific and Specific responses © 2013 Pearson Education, Inc.  The Concept of Immunity ▪ Susceptibility: lack of resistance to a disease ▪ Immunity: ability to ward off disease ▪ Innate immunity: defenses against any pathogen ▪ Adaptive immunity: immunity or re...

Non-specific and Specific responses © 2013 Pearson Education, Inc.  The Concept of Immunity ▪ Susceptibility: lack of resistance to a disease ▪ Immunity: ability to ward off disease ▪ Innate immunity: defenses against any pathogen ▪ Adaptive immunity: immunity or resistance to a specific pathogen © 2013 Pearson Education, Inc.  First line of defense © 2013 Pearson Education, Inc. Physical Factors ▪ Skin Epidermis consists of tightly packed cells with Keratin ▪ Mucous membranes − Mucus: traps microbes − Ciliary escalator: transports microbes trapped in mucus away from the lungs © 2013 Pearson Education, Inc. Physical Factors ▪ Lacrimal apparatus: washes eye ▪ Saliva: washes microbes off ▪ Urine: flows out ▪ Vaginal secretions: flow out Chemical Factors ▪ Fungistatic fatty acid in sebum ▪ Low pH (3–5) of skin ▪ Lysozyme in perspiration, tears, saliva, and urine ▪ Low pH (1.2–3.0) of gastric juice ▪ Low pH (3–5) of vaginal secretions © 2013 Pearson Education, Inc. Normal Microbiota and Innate Immunity ▪ Microbial antagonism/competitive exclusion: normal microbiota compete with pathogens or alter the environment ▪ Commensal microbiota: one organism (microbe) benefits, and the other (host) is unharmed ▪ May be opportunistic pathogens © 2013 Pearson Education, Inc.  Second line of defense © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.  Macrophage ▪ Neutrophils ▪ Fixed Bacterium macrophages ▪ Wandering macrophages Pseudopods © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.  Inflammation © 2013 Pearson Education, Inc.  Fever ▪ Abnormally high body temperature ▪ Hypothalamus is normally set at 37°C ▪ Endotoxins activate phagocytes ▪ Hypothalamus releases prostaglandins that reset the hypothalamus to a high temperature ▪ Body increases rate of metabolism, and shivering occurs, which raise temperature ▪ Vasodilation and sweating: body temperature falls (crisis) © 2013 Pearson Education, Inc.  The Complement System ▪ Serum proteins activated in a cascade ▪ Enhanced phagocytosis ▪ Membrane attack complex: cytolysis ▪ Attract phagocytes © 2013 Pearson Education, Inc.  Third line of defense © 2013 Pearson Education, Inc.  Specific Responses Specific defenses are those that give us immunity to certain diseases. In specific defenses, the immune system forms a chemical “memory” of the invading microbe. If the microbe is encountered again, the body reacts so quickly that few or no symptoms are felt. Humoral immunity describes immune actions taking place in these extracellular fluids, brought about by protective molecules called antibodies. Another term for antibody is immunoglobulin (Ig). Antibodies recognize and combat foreign molecules called antigens. Antibodies  Antibody: a protein produced by the human immune system to tag and destroy invasive microbes. Antigen: any protein that our immune system uses to recognize “self” vs. “not self.” Antibodies can attach to B cells and serve to recognize foreign antigens. B cells produce antibodies Free antibodies can bind to antigens which “tags” the antigen for the immune system to attack and destroy. The results of antigen–antibody binding. The immune response (Short)  Antigen recognition Cells of the immune system are “trained” to recognize “self” proteins vs. “not self” proteins. If an antigen (“not self”) protein is encountered by a macrophage, it will bring the protein to a helper T-cell for identification. If the helper T-cell recognizes the protein as “not self,” it will launch an immune response  Helper T-Cells Helper T-cells have receptors for recognizing antigens. If they are presented with an antigen, they release cytokines to stimulate B-cell division. The helper T-cell is the key cell to signal an immune response. If helper T-cells are disabled, as they are in people with AIDS, the immune system will not respond.  B-cells B-cells in general produce antibodies. Those with antibodies that bind with the invader’s antigen are stimulated to reproduce rapidly. B-cells differentiate into either plasma cells or memory B-cells. Plasma cells rapidly produce antibodies. Memory cells retain the “memory” of the invader and remain ready to divide rapidly if an invasion occurs again.  T-cells While B-cells divide and differentiate, so do T- cells. Some T-cells become cytotoxic, or “killer” T- cells. These T-cells seek out and destroy any antigens in the system, and destroy microbes “tagged” by antibodies. Some cytotoxic T-cells can recognize and destroy cancer cells.