Chapter 49 The Immune System in Animals1. 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: Measles2. Immunizationa. The conferring of immunity to a particular disease-by giving a weakened strain of the disease so individual develops immunityb. Edward Jenner noticed that milkmaids did not get smallpoxc. Cows suffered from a smallpox-like disease called cowpoxd. Jenner injected a boy w. cowpox then later injected smallpox-the boy did not get smallpox3. Vaccinationa. Injection of a weakened, killed, or altered pathogen-to stimulate development of immunity against a pathogenb. Pathogen=an entity capable of causing a disease like a virus or bacteria4. Two Types of Immunity1. Innate immunity-an immune system ready to respond to foreign invaders at all times-is nonspecific and responds in the same way to all infections2. 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 responsecells responding to smallpox virus will not respond to measles virus4. Terms to Definea. Antigen-any foreign molecule that can initiate an immune response-proteins, glycoproteins, or lipids-proteins or glycoproteins on viruses or bacteriab. Immune responses are made to the proteins on the bacteria not the bacteria itself-4 diff. antibodies will recognize the organism5. Innate Immunitya. 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 lungs6. The Innate Immune Response: The Cellsa. blood contains two types of cellsb. Erythrocytes-the red blood cells that carry O2 to the body and have no nucleusc. Leukocytes-the white blood cells which mediate the specific and innate immune responses7. Three Important Leukocytesa. 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 bacteriab. Macrophages-phagocytic cells-secrete chemical messengers called cytokines that will recruit other cells to the infection sitec. Mast Cells=release chemical messengers like histamine-histamines: meant to expell parasites and often responds to chemicals that cause allergic reactions8. Woundsa. 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 siteb. Netrophils and macrophages remove pathogens by phagocytosisc. The inflammatory response continues until:-the foreign material is eliminated and the wound is repaired-but sometimes this is not enough9. The Adaptive Immune Responsea. Specificity: specific immune system cells respond to specific pieces of antigensb. Diversity: can respond to almost any foreign moleculec. Memory: the second time you encounter the antigen you respond faster and strongerd. Self-nonself recognition-can distinguish between what is self and what is foreigne. There are auto-immune diseases in which the immune system kills its own cellsf. Adaptive Immune Response produces antibodies-which are proteins produced by the adaptive immune system cells that bind to specific antigens10. Lymphocytesa. The cells involved int he acquired immune responseb. Lymphocytes are also Leukocytes (white blood cells)-when they dont encounter antigen they are in G0 phase11. Lymphocytes Travel through the bodya. Through the blood circulatory system and the lymphatic systemb. 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 lymphocytes12. Lymphocytes Are Activated In:a. the spleen-the organ that filters the bloodb. Lymph Nodes-small oval organs that filter the lymphc. Lymphocytes constantly circulate from lymph node to node to spleen etc.-looking for their specific antigend. lymphocytes are not activated in the blood or lymph13. Lymphocytes Consist of 2 Main typesa. B-Lymphocytes or B cells-are produced and mature int he bone marrow-and produce antibodiesb. T-cells-produced and mature in the Thymus14. Two Types of T-Cellsa. Cytotoxic T cells-kill cells that are infected with a virus-have the CD8 protein on their surfaceb. Helper T Cells-master controllers of the Adaptive Immune Response-have the CD4 protein on their surface15. How do B cells Recognize Antigens?a. B-cell receptor (BCR)-a protein on the surface of B cells that binds to antigensb. The BCR has the same structure as the antibodies produced by B cellsc. The BCR and the antibodies are both immunoglobulins-generic name for these proteinsd. Antibodies-generally refers to these proteins when binding to a specific region-like anti-measles virus antibodye. 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 membranef. Antigen Binding Site-is made of -the end of one light chain+the end of one heavy chain16. 5 Classes of Immunoglobinsa. IgG-most abundant type of anti-body-found in blood and interstitial fluid-protects against bacteria, viruses and toxinsb. 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 newbornsc. IgM-pentamer: made of 5 monomers-first antibody produced in infections-very good at clumbing bacteria and virusesd. IgD-found only as a BCR on B cells and is involved in activation of B cells by antigene. IgE-very rare. involved in allergies and killing parasitic worms17. How Do T Cells Recognize Antigensa. The T Cell receptor (TCR)-has a shape similar to one arm of the BCR-is never produced as a secreted proteinb. Why have T Cell Receptors-dont want the potent killer cells or regulatory cells to become activated unless we need them18. We Can Respond to 10^12 diff. antigensa. But each B Cell or T cell responds to only one antigen19. Immunoglobinsa. A constant (C) Region-same for all Igs heavy or light chain-or for all TCRs alpha or beta chainsb. A variable (V) region-the amino acid seq. were diff. for diff. Igs or TCRsc. These variable regions are the antigen binding sites20. How Do We Produce 10^12
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