Chapter 49 The Immune System in Animals 1 People who get bacterial or viral infections and recover develop immunity to that disease They do not get the same disease in the future Example Measles 2 Immunization a The conferring of immunity to a particular disease by giving a weakened strain of the disease so individual develops immunity b Edward Jenner noticed that milkmaids did not get smallpox c Cows suffered from a smallpox like disease called cowpox d Jenner injected a boy w cowpox then later injected smallpox the boy did not get smallpox 3 Vaccination a Injection of a weakened killed or altered pathogen to stimulate development of immunity against a pathogen b Pathogen an entity capable of causing a disease like a virus or bacteria 4 Two Types of Immunity 1 Innate immunity an immune system ready to respond to foreign invaders at all times is nonspecific and responds in the same way to all infections 2 Acquired Immunity requires cells to be activated to respond to an infection is extremely specific responds only o particular foreign molecule or organism that induced their response cells responding to smallpox virus will not respond to measles virus 4 Terms to Define a Antigen any foreign molecule that can initiate an immune response proteins glycoproteins or lipids proteins or glycoproteins on viruses or bacteria b Immune responses are made to the proteins on the bacteria not the bacteria itself 4 diff antibodies will recognize the organism 5 Innate Immunity a Barriers to the entry of microbes skin physical and chemical barrier tears and saliva wash away microbes mucus traps microbes so that they can not swim tot he actual cells inside the body cilliated cells beat to remove microbes from the lungs 6 The Innate Immune Response The Cells a blood contains two types of cells b Erythrocytes the red blood cells that carry O2 to the body and have no nucleus c Leukocytes the white blood cells which mediate the specific and innate immune responses 7 Three Important Leukocytes a Neutrophils professional phagocytic cells secrete lysozyme which degrades the bacterial cell wall is an anti bacterial enzyme produce Reactive Oxygen Intermediates oxygen radicals and hydrogen peroxide that kill bacteria b Macrophages phagocytic cells secrete chemical messengers called cytokines that will recruit other cells to the infection site c Mast Cells release chemical messengers like histamine histamines meant to expell parasites and often responds to chemicals that cause allergic reactions 8 Wounds a Macrophages at a wound release chemokines which are special kinds of cytokines which set up a gradient that other cells can sense recruit neutrophils to the site b Netrophils and macrophages remove pathogens by phagocytosis c The inflammatory response continues until the foreign material is eliminated and the wound is repaired but sometimes this is not enough 9 The Adaptive Immune Response a Specificity specific immune system cells respond to specific pieces of antigens b Diversity can respond to almost any foreign molecule c Memory the second time you encounter the antigen you respond faster and stronger d Self nonself recognition can distinguish between what is self and what is foreign e There are auto immune diseases in which the immune system kills its own cells f Adaptive Immune Response produces antibodies which are proteins produced by the adaptive immune system cells that bind to specific antigens 10 Lymphocytes a The cells involved int he acquired immune response b Lymphocytes are also Leukocytes white blood cells when they dont encounter antigen they are in G0 phase 11 Lymphocytes Travel through the body a Through the blood circulatory system and the lymphatic system b Lymphatic system is a network of vessels that collect excess fluid from the tissues and returns it to the blood lymph a mixture of fluid and lymphocytes 12 Lymphocytes Are Activated In a the spleen the organ that filters the blood b Lymph Nodes small oval organs that filter the lymph c Lymphocytes constantly circulate from lymph node to node to spleen etc looking for their specific antigen d lymphocytes are not activated in the blood or lymph 13 Lymphocytes Consist of 2 Main types a B Lymphocytes or B cells are produced and mature int he bone marrow and produce antibodies b T cells produced and mature in the Thymus 14 Two Types of T Cells a Cytotoxic T cells kill cells that are infected with a virus have the CD8 protein on their surface b Helper T Cells master controllers of the Adaptive Immune Response have the CD4 protein on their surface 15 How do B cells Recognize Antigens a B cell receptor BCR a protein on the surface of B cells that binds to antigens b The BCR has the same structure as the antibodies produced by B cells c The BCR and the antibodies are both immunoglobulins generic name for these proteins d Antibodies generally refers to these proteins when binding to a specific region like anti measles virus antibody e Immunoglobulin is made of 4 polypeptides two identical light chains two identical heavy chains The Transmembrane domain of the BCR anchors the protein in the plasma membrane f Antigen Binding Site is made of the end of one light chain the end of one heavy chain 16 5 Classes of Immunoglobins a IgG most abundant type of anti body found in blood and interstitial fluid protects against bacteria viruses and toxins b IgA Dimer Made of 2 monomers found in external excretions Tears saliva mucous etc prevents bacteria and viruses from attaching to the body found in milk to protect newborns c IgM pentamer made of 5 monomers first antibody produced in infections very good at clumbing bacteria and viruses d IgD found only as a BCR on B cells and is involved in activation of B cells by antigen e IgE very rare involved in allergies and killing parasitic worms 17 How Do T Cells Recognize Antigens a The T Cell receptor TCR has a shape similar to one arm of the BCR is never produced as a secreted protein b Why have T Cell Receptors dont want the potent killer cells or regulatory cells to become activated unless we need them 18 We Can Respond to 10 12 diff antigens a But each B Cell or T cell responds to only one antigen 19 Immunoglobins a A constant C Region same for all Igs heavy or light chain or for all TCRs alpha or beta chains b A variable V region the amino acid seq were diff for diff Igs or TCRs c These variable regions are the antigen binding sites 20 How Do We Produce 10 12 diff Igs or TCRs a 10 12 diff genes No b
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