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Immune System 1 What It’s All About – the BASICS • Defend the body against pathogens • Recognize self from non-self • Specific and Non-specific “Bottom line”: Fight infection through the production of cells that inactivate foreign substances/cells 2 Protection • Pathogens – Infectious disease – Toxic – Reproduce in the host – GERMS • Koch’s postulate 3 4 4 ways of getting sick • Contact an infected person directly 5 4 ways of getting sick • Contact an infected person INdirectly 6 4 ways of getting sick • Eat infected food or drink infected water 7 4 ways of getting sick • Get bitten by an infected animal 8 Bubonic Plague Bubonic plague is an infectious disease, circulating mainly among small rodents and their fleas. Without treatment, the bubonic plague kills about two thirds of infected humans within 4 days. Swollen lymph glands are typical symptoms of the plague. During the 14th century, 25 million people in Europe were belived to have died (around 40% of the entire population). 9 Immune System Anatomy • Lymphatic System –Lymph (fluid with WBCs) –Lymph nodes (store WBCs) –Tonsils, thymus, spleen, appendix, red bone marrow, adenoids 10 11 Line up the Troops • First line of defense is non-specific – Blocks anything from entering body system 12 First Line of Defense Examples • • • • Skin: wall that blocks pathogens Sweat: acidic, salty, contains enzymes Mucus: coats openings to body Tears: wash out pathogens entering eye 13 If that didn’t work…. • Second line of defense: Inflammatory Response When the pathogen enters the body – Injured cells release HISTAMINE • Capillaries expand so blood flow increases • Fluid leaks out into space between cells – Swelling, redness, pain, heat 14 SPECIFIC DEFENSE IMMUNE RESPONSE – Specific for pathogen – Most effective if you’ve been infected before – Through entire body – Triggered by substance in pathogen = antigen – Can be defense in body fluids (humoral) OR defense against abnormal cells or pathogens (cell-mediated) 15 Cells Involved White Blood cells = LEUKOCYTES They are made in the bone marrow Some develop in bone marrow, others in the thymus 16 Cells Specifics Non-specific: Phagocytes: engulf (eat) and digest pathogens Macrophages are the biggest Specific: Lymphocytes: B-cells and Tcells 17 Humoral Immunity – Immunity against pathogens in body fluids Some B cells recognize specific pathogen • B cells mature in Bone marrow • Antibodies from B-cells • Some B cells remember specific antigens & will produce antibodies whenever the pathogen reappears (memory cells) • Antibodies: – Attach to antigen and attract macrophages 18 10 to 17 days for full response B cell immune responseY Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y release antibodies Y Y Y recognition Y Y Y plasma cells Y Y Y Y Y Y Y Y Y Y Y Y captured invaders Y “reserves” Y memory cells Y B cells + antibodies Y Y Y Y invader (foreign antigen) Y Y Y tested by B cells (in blood & lymph) Y clone 1000s of clone cells 19 Lymphocytes: B-cell 20 Cell-Mediated Immunity • Cells directly attack and destroy Ag (antigen) – Cancer cells, infected body cells, invading cells • T cells involved – Born in bone marrow but mature in Thymus – 3 types: killer, helper, suppressor 21 T cells • Killer T cells – Attack Ag (puncture cell membrane) • Helper T cells (aka T4) – Stimulate Killer Ts to divide, stimulate B cells to divide and release Antibodies • Suppressor T cells – Stop the activity of other T cells 22 T cell response infected cell killer T cell helper T cell or activated macrophage activate killer T cells helper T cell helper T cell stimulate B cells & antibodies helper T cell Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y helper T cell Y Y 23 Lymphocytes From Stem Cells 24 Lymphocytes: T-cell 25 Memory Cells Primary response: new pathogen, new response (5-10 days until max production of B and T cells) Secondary Response: same pathogen, old response (1-2 days, so you don’t even get sick!) Memory cells can last your entire life!! 26 Vaccinations • Immune system exposed to harmless version of pathogen – triggers active immunity – stimulates immune system to produce antibodies to invader – rapid response if future exposure • Most successful against viral diseases 27 Immune response pathogen invasion antigen exposure skin free antigens in blood humoral response memory B cells Y Y Y Y Y Y antibodies Y Y Y macrophages (APC) cellular response T cells memory T cells cytotoxic T cells Y Y plasma B cells antigens on infected cells helper T cells B cells skin 28 HIV and AIDS • HIV attacks T4 cells (Helper T cells) • Body can’t defend against any Ags! • Known as an STD: transported in semen, blood, breast milk • Once T4 count is so low that body can’t fight disease, we say the person has AIDS • Takes about 10 years to develop AIDS 29 AIDS Infection 30 Huge Outbreak in Africa African Children Orphaned by AIDS 31 32 Allergies 33 Allergies • Histamine released even though antigen is harmless • If blood vessels dilate too much: ANAPHYLACTIC SHOCK 34 Autoimmune Disorders • Immune system attack SELF cells • Multiple Sclerosis: T cells destroy nerve cells • Maybe Type 1 Diabetes is attack on pancreas 35 Multiple Sclerosis 36