1. The immune system By: Jedi master harrison

2. The body’s defense system NONSPECIFIC MECHANISMS (general barriers to infection) LAYERS OF DEFENSE: SKIN MUCOUS MEMBRANE INTERACTING MECHANISMS PHAGOCYTOSIS ANTIMICROBIAL PROTEINS THE INFLAMMATORY RESPONSE FIRST LINE OF DEFENSE SECOND LINE OF DEFENSE

4. Cuts or abrasions can allow potentially harmful bacteria or viruses to enter the body.The skin is like a force field around the body. It keeps unwanted invaders out!

5. Mucous membrane PERSONAL SHIELDS Lines the digestive, respiratory and genitourinary tracts Bars entry of harmful microbes Also counters pathogens with chemical defenses *saliva, tears, and mucous secretions bathe the surface of exposed epithelia washing away many potential invaders EX: LYSOZYME- an enzyme that digest the cell walls of many bacteria and destroys many microbes entering the upper respiratory system and the openings around the eyes. It’s like personal shields for your LUNGS, INTESTINES, AND THE GENITOURINARY TRACT.

6. Mucous membrane at work EXAMPLES OF THE MUCOUS MEMBRANE AT WORK: Mucus: the viscous fluid secreted by cells of the mucous membranes; it traps particles that contact it. Lining the trachea are specialized epithelial cells equipped with cilia that sweep out microbes and other particles trapped by the mucus, which keeps them from entering the lungs. If microbes in food or that are trapped in mucus are swallowed, it must pass through the highly acidic gastric juice produced by the stomach lining. This destroys most of the microbes before they can enter the intestinal tract.

8. Attracted by chemical signals, neutrophils can leave the blood and enter infected tissue by amoeboid movement.

10. Monocytes mature into MACROPHAGESNeutrophils are like SUICIDE BOMBERS! Macrophages continued on next slide  The second line of defense

12. They also stimulate lymphocytes and other immune cells to respond to pathogens

13. A majority of macrophages are stationed at strategic points where microbial invasion is likely to occur (LIKE A BLOCKADE)

14. Fixed macrophages are especially numerous in the lymph nodes and in the spleen, which are key organs of the lymphatic system.Blockade of Naboo

15. EOSINOPHILS About 1.5% of the white cells Their defend against larger parasitic invaders such as worms Don’t attack microorganisms directly Destroy the body’s own infected cells, especially cells harboring viruses Also attack cells that could form tumors The attack is not by phagocytosis but an attack on the membrane of the target cell This causes the cell to break open Natural killer cells

16. The most important antimicrobial proteins in the blood and tissues are interferons and the complement system. INTERFERONS: proteins secreted by virus-infected cells that inhibit neighboring cells from making new viruses COMPLEMENT PROTEINS: involved in nonspecific and specific defense Can lyse a cell target by combining with antibodies A local inflammatory responseis triggered by tissue damage. Injured cells release histamine, a chemical signal that dilates blood vessels and increases capillary permeability allowing large numbers of phagocytic white blood cells to enter the interstitial fluid. Antimicrobial proteins

17. Specific defenders The immune system recognizes foreign microbes, toxins or transplanted tissues It knows that they don’t belong It then develops an immune response to inactivate or destroy the specific type of invader ANTIGEN: a foreign substance that elicits an immune response Most antigens are proteins or large polysaccharides Antigens that trigger an immune response include molecules belonging to viruses, bacteria, fungi, protozoa, and parasitic worms. ANTIBODIES: specialized lymphocytes that defend the body against one specific type of antigen. Antibodies make up a class of proteins called immunoglobulins An antibody does not usually destroy an antigen directly but targets it for elimination by complement or phagocytes

18. IMMUNITY Immunity is the result of the immune system’s enhanced response to a previously encountered pathogen. ACTIVE IMMUNITY: acquired by exposure to an actual disease or to a vaccine that simulates a disease. PASSIVE IMMUNITY: acquired by administering antibodies formed in others, or it can be passed from mother to child via the placenta and milk.

19. HUMORAL IMMUNITY: based on circulation of antibodies in the blood and lymph, and defends against free viruses, bacteria, and other extracellular threats. CELL-MEDIATED IMMUNITY: reacts against transplanted tissue and cancer cells. Two main functional branches of immunity It’s not a joke!

20. LYMPHOCYTES=main cells of the immune system LYMPHOCYTES: Originate in bone marrow B LYMPHOCYTES: mature in the bone marrow and function in humoral immunity. B cells defend against pathogens in body fluids by generating specific antibodies T LYMPHOCYTES: mature in the thymus and function mainly in cell-mediated immunity. T cells defend against intracellular pathogens

21. Clonal selection of lymphocytes Is the cellular basis for immunological specificity and diversity Each lymphocyte recognizes and responds to only one antigen There is an enormous diversity of antigen-specific lymphocytes. This allows the immune system to defend against an almost unlimited variety of antigens HOW IT WORKS: Each lymphocytes’ specificity for an antigenic target is predetermined during embryonic development (before an encounter with an antigen ever takes place) The mark of this specificity is the antigen receptor the lymphocyte bears on its surface If that antigen enters the body and binds to receptors on the specific lymphocytes, then those lymphocytes are activated to mount an attack (immune response) The selected cells go through cell division and develop into a large number of a clone of cells that combats the antigen that initiated the response. DON’T HAVE TO WRITE CLONE TROOPERS

22. CELL MEMORY of immunity Upon first exposure to an antigen lymphocytes go through PRIMARY IMMUNE RESPONSE PRIMARY IMMUNE RESPONSE: between initial exposure to an antigen and maximum production of effector cells, there is a lag period of 5 to 10 days. During this lag period, the lymphocytes selected by the antigen are differentiating into effector T cells and antibody-producing plasma cells. If the body is exposed to the same antigen at some time later, the response is faster (only 3 to 5 days) and more prolonged than the primary response. SECONDARY IMMUNE RESPONSE: the antibodies produced at this time are also more effective in binding to the antigen than those produced during the primary response. IMMUNOLOGICAL MEMORY: The immune system’s ability to recognize an antigen that it already encountered IMMUNOLOGICAL MEMORY is possible due to MEMORY CELLS

23. MEMORY CELLS MEMORY CELLS are produced along with the relatively short-lived effector cells of the primary immune response. During the primary response, memory cells are inactive Survive for long periods of time Multiply rapidly when exposed again to the same antigen that caused their formation Memory cells are responsible for the usual lifelong immunity of chickenpox after childhood exposure

24. Molecular markers Molecular markers on cell surfaces function in self/nonself recognition SELF-TOLERANCE: develops as T and B lymphocytes bearing antigen receptors mature in the thymus and bone marrow, and continues to develop even as the cells migrate to lymphoid tissues. Any lymphocytes with receptors for molecules present in the body are destroyed or are made nonfunctional This leaves only lymphocytes that are reactive against foreign molecules MAJOR HISTOCOMPATIBILITY COMPLEX (MHC): a biochemical fingerprint unique to each individual 2 TYPES OF MHC: CLASS I MHC: LOCATED ON ALL NUCLEATED CELLS (ALMOST EVERY CELL IN THE BODY) CLASS II MHC: RESTRICTED TO A FEW SPECIALIZED CELL TYPES OF THE BODY’S DEFENSE SYSTEM (MACROPHAGES, B CELLS, AND ACTIVATED T CELLS)