BIOL 252 1st EditionExam #3 Study Guide Lectures: 15-20The Lymphatic and Immune SystemLymphatic System- Lymphatic capillaries => collecting vessels => lymphatic trunks => collecting ducts- Functionso Fluid recovery Fluid comes from tissues (interstitial fluid)o Lipid absorption Lipids go through lymphatic systemo Immunity Lymph nodes and other organs use lymph to screen body for pathogensLymphatic 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 veinso Right lymphatic duct and thoracic ductLymphatic Tissues- Mucosa Associated Lymphatic Tissue (MALT) is common beneath the mucosa of the digestive, respiratory, reproductive, urinary systemLymphatic Organs- Tonsils- Thymus (where T cells mature)- Spleen (filters blood)- Lymph nodes o Where lymphocytes gather to come in contact w/ pathogenso Lymph comes from excess interstitial tissue fluido Filter lymphNonspecific Defenses- React the same way regardless of what the pathogen is- Physical Barrierso 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 macrophageso Made in red bone marrowo 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 cellso Non-selective lymphocytes that destroy cancerous or infected cellso Releases perforins – pokes holes in cell membraneo Releases granzymes that flow through pores and kill cell o Cells die by apoptosis o Present in blood, lymph, lymphatic tissue/organs- Defensive proteinso Interferons: newly infected cells send warning message to neighbors; response includes antiviral proteins (AVPs)o Limits infection rather than stopping ito 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” - Inflammationo Signs: swelling, heat, redness, pain, itchinesso Result of inflammatory responseo Inflammatory chemicals cause RBC to move into area- Fevero Raise in body’s temperatureo Hypothalamus in charge and keeps body temperature hovering around 37Co Infection and pyrogen secretion => hypothalamic thermostat is reset to higher set point Benefits: chemical reactions go faster o Onset – body temperature riseso Body temperature oscillates around new set pointo Infection ends, set point returns to normal => body temp returns Specific Defenses- Includes: T and B cells, antigen presenting cells- T cellso Cytotoxic (CD8) Cell killers o Helper (CD4) Facilitate Tc cell and B cell activationo Regulatory T cells Terminate immune responseo 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 bloodo Learn self tolerance and immunocompetenceo Self tolerance: do not attack yourself (only virus-infected you)o Get rid of one’s that are not self toleranto 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 anythingo Mixture of both Immunocompetent and not- B cellso Born in the bone marrowo Go to other places in the body (skip the thymus entirely)o Go through selection in the bone marrowo Do not have receptors; have antibodies- Antigen presenting cellso Can be any cell in your bodyo But there are “professionals” o Most common APCs: macrophages, dendritic cells, B cellso Engulf bacterium, break it apart, antigen (macromolecule) is taken by MHC and presented on surface of the cell - Cellular immunityo Tc antigen recognition => clonal selectiono Small population => memory T cellso Majority of T cells that result from multiple rounds of mitosis = more Tc 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 Immunityo B cells – exposed to antigenso 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 surfaceo Needs helper T cell to recognize that it is foreigno Helper T cell recruited to “flip the switch” allowing B cell to respondo 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 complexo 1. Work in conjunction w/ complement (activation of complement) Promotes inflammation, lysis, phagocytosiso 2. Neutralizationo 3. Agglutinationo 4. Precipitationo 2-4 inactivate Result in phagocytosis- Antibodies- Immunological Memoryo Primary response  B cell is recognizes antigen Takes a long amount of time to elicit a