BIOL 252 1st Edition Exam 3 Study Guide Lectures 15 20 The Lymphatic and Immune System Lymphatic System Lymphatic capillaries collecting vessels lymphatic trunks collecting ducts Functions o Fluid recovery Fluid comes from tissues interstitial fluid o Lipid absorption Lipids go through lymphatic system o Immunity Lymph nodes and other organs use lymph to screen body for pathogens Lymphatic Vessels and Lymph Lymphatics parallel the venous system found throughout the body Purpose of capillary exchange o What moves in and out Oxygen CO2 nutrients waste Fluid recovery interstitial fluid flows continuously from capillaries and exits tissue as lymph Collecting ducts o Two lymphatic ducts drain all lymph to subclavian veins o Right lymphatic duct and thoracic duct Lymphatic Tissues Mucosa Associated Lymphatic Tissue MALT is common beneath the mucosa of the digestive respiratory reproductive urinary system Lymphatic Organs Tonsils Thymus where T cells mature Spleen filters blood Lymph nodes o Where lymphocytes gather to come in contact w pathogens o Lymph comes from excess interstitial tissue fluid o Filter lymph Nonspecific Defenses React the same way regardless of what the pathogen is Physical Barriers o Skin Keratinized stratified epithelium Secretions acid mantle dermicidin o Mucous membranes Acid mucus lysozyme breaks down bacteria o Beyond the epithelium Hyaluronic acid viscous component of ECM Leukocytes WBC and macrophages o Made in red bone marrow o Phagocytes Macrophages big cells phage engulfs work in part by engulfing bacteria Neutrophils and eosinophils engulf pathogens through phagocytosis o Basophils mast cells Signal to phagocytes and lymphocytes Blood cell basophil Mast cell connective tissue cell Release hormones and attract other cells to site of injury or injection By dilating or hemo attraction release chemicals Histamine vasodilator Leukotrienes attract leukocytes Heparin anticoagulant Natural killer cells o Non selective lymphocytes that destroy cancerous or infected cells o Releases perforins pokes holes in cell membrane o Releases granzymes that flow through pores and kill cell o Cells die by apoptosis o Present in blood lymph lymphatic tissue organs Defensive proteins o Interferons newly infected cells send warning message to neighbors response includes antiviral proteins AVPs o Limits infection rather than stopping it o Complement Lyse bacteria through formation of pore complexes part of non specific Label bacteria for destruction by antibodies part of specific response Enhance inflammatory response Work with antibodies hence complement Inflammation o Signs swelling heat redness pain itchiness o Result of inflammatory response o Inflammatory chemicals cause RBC to move into area Fever o Raise in body s temperature o Hypothalamus in charge and keeps body temperature hovering around 37C o Infection and pyrogen secretion hypothalamic thermostat is reset to higher set point Benefits chemical reactions go faster o Onset body temperature rises o Body temperature oscillates around new set point o Infection ends set point returns to normal body temp returns Specific Defenses Includes T and B cells antigen presenting cells T cells o Cytotoxic CD8 Cell killers o Helper CD4 Facilitate Tc cell and B cell activation o Regulatory T cells Terminate immune response o Memory T cells Descend from activated Tc responsible for memory in cellular immunity Can potentially respond to anything Make T cells in bone barrow Travel to thymus through the blood o Learn self tolerance and immunocompetence o Self tolerance do not attack yourself only virus infected you o Get rid of one s that are not self tolerant o Immunocompetence ability to function in the immune system Ability to respond to MHC major histocompatibility complex on antigen presenting cells o Somehow a T cell never makes it to the thymus and grows up happily in the spleen Which is a consequence of this scenario T cell will be able to bind MHC but not recognize foreign antigens T cell will be able to bind MHC and recognize foreign antigens Answer T cell will be unable to bind MHC but not recognize foreign antigens If we go to thymus come out with ONLY Immunocompetent cells If it doesn t go to the thymus we can t conclude anything o Mixture of both Immunocompetent and not B cells o Born in the bone marrow o Go to other places in the body skip the thymus entirely o Go through selection in the bone marrow o Do not have receptors have antibodies Antigen presenting cells o Can be any cell in your body o But there are professionals o Most common APCs macrophages dendritic cells B cells o Engulf bacterium break it apart antigen macromolecule is taken by MHC and presented on surface of the cell Cellular immunity o Tc antigen recognition clonal selection o Small population memory T cells o Majority of T cells that result from multiple rounds of mitosis more T c cells All have ability to respond to same antigen Can find an enemy cell and deliver lethal hit Release perforins create holes Release granzymes which enter target cell and result in apoptosis o TH cell has gone through selection process in thymus in same way Make helper T cells for now memory T cells for later Secrete interleukins Chemicals that attract white blood cells Enhances immune system response do not kill any cells Humoral Immunity o B cells exposed to antigens o Each B ell has one type of antibody which is different than its neighbor s o B cells respond to antigen by taking it in and transfer to MHC put it on the surface o Needs helper T cell to recognize that it is foreign o Helper T cell recruited to flip the switch allowing B cell to respond o Clonal selection B cell divides repeatedly Some become memory B cells Most become plasma cells Pumps releases antibodies into the body Antibodies when recognize antigen bind it Antigen antibody complex o 1 Work in conjunction w complement activation of complement Promotes inflammation lysis phagocytosis o 2 Neutralization o 3 Agglutination o 4 Precipitation o 2 4 inactivate Result in phagocytosis Antibodies Immunological Memory o Primary response B cell is recognizes antigen Takes a long amount of time to elicit a response producing antibodies Has to get permission from helper T cell Making plasma and memory cells o Secondary response Body does not produce symptoms but still exposed to the virus What about a memory B cell allows this response to happen quickly More memory B cells than original B cells Become plasma cells