Exam 2 Barriers Innate Immunity comes with birth first response to pathogens Exterior structures that prevent entry Interior detection and response systems 02 19 2014 Most important to infection deterrence Skin made of dead cells Gaps are covered with mucus Other gaps are protected by secretions o Tears contain lysozyme acts as antibiotic Innate Immune Response White Blood cells Leukocytes immediate and generic response to a general type of pathogen Antigen any molecule that can initiate an immune response 1 Toll Like Receptors subset of Pattern recognition receptors signal presence of molecules associated with pathogens 2 TLRs on leukocytes surface signal a cascade that have different effects based on what type of TLR it is TLRs in humans signal for the expression secretion of cytokines cell movers which attract other cells into action at the site of 3 After initial signal of invasion is received INFLAMMATORY RESPONSE Bacteria Enters Platelets from blood release blood clotting proteins Macrophages release chemokines chemical movers to recruit infection other cells o Gradient formed that marks path to wound site Mast cells release histamine which causes blood vessels to constrict at site Histamine causes dilation in blood vessels farther from the wound o Neutrophils Leukocytes migrate out of dilated vessels towards site of infection engulf invading cells thru phagocy o Lysozymes inside Neutrophils degrade invading cells Adaptive Immunity ability to react and recognize to specific antigens Antibodies proteins bind to specific part of antigen epitope o Specific diverse memory self nonself recognition Lymphocytes 2 types marrow o B cells from bursa produce antibodies mature in bone Receptor 2 light chains 2 heavy chains held together by disulfide bonds both have variable pieces and Antibody is identical except no trans membrane constants piece IMMUNOGLOBULINS 5 types of proteins which BCR and antibodies belong to o T cells from thymus graft rejection recognize and kill host cells that are infected with a virus mature in thymus Receptor alpha and beta chains two parallel arms both have variable and constants Require other cells to process antigens present them to the TCR aka antigen presentation Origin bone marrow tissue Maturation Bone marrow b and Thymus t Activation Spleen and Lymph Nodes o Lymph nodes filter lymph lymphocytes and fluid Transport circulate through blood and lymphatic system Gene recombination is the mechanism responsible for the diversity of the adaptive immune system B CELLS AND T CELLS NEED TO KNOW SELF FROM NON SELF Lymphocyte cells die if they never encounter the epitope they re programmed for Clonal Theory of Selection Lymphocytes are activated when they bind to epitope of the antigen The activated lymphocytes are cloned and they endure longer if the antigen ever returns Activation is a controlled process however ACTIVATION 2 types o T cell Activation Leukocytes that are dendritic cells gather antigens and report to the lymph nodes Dendritic cells have MHC major histocompatibility proteins that process and present the epitopes to the T cells Class I MHC bind antigens inside ER proteins that are loaded on to this type are from the Class II MHC bind antigens inside endosomes proteins loaded onto this class are obtained from cytosol CD8 cells external environment CD4 cells Complex activation process begins between proteins on dendritic cell MHCs and CD4 CD8 cell Cytokines also needed usually for CD8 cells activation Activated T cell then divides CD8 cells form daughters that are cytotoxic T lymphocytes or Killer T s that kill infected cells CD4 cells form daughters that are helper T cells that activate other cells in immune response The New Effector T cells go to site of infection to help o B cell Activation When activated a bunch of ER are produced to create secrete antibodies Cell grows a lot BCR antigen meet B cell displays the epitope on its own cell surface using MHC class II proteins Activated T helper cell is stimulated by MHC peptide complex on surface of B cell B cell is activated by helper t cell and goes to work Some differentiate into plasma cells and make Somatic hypermutation fine tuning of BCRs that kills off the ones that don t respond well to antigens and makes antibodies others fit better Mechanisms of Defenses for Adaptive Immune system Cell mediated response takes place via cell to cell contact promoted by Th2 cells and activated CD8 cytotoxic T lymphocytes Humoral response promoted by Th1 cells and involves production of antibodies secreted into the blood and lymph humor fluid External pathogens are eliminated by 1 Opsonization prep for eating pathogens tagged with antibodies are readily destroyed by phagocytes 2 Neutralization coated pathogens cannot infect host cells and cannot interact so they re neutralized 3 Agglutination gluing together clumping of antigens makes for easy targets of phagocytosis and stops them from infecting cells 4 Co stimulation of complement proteins binded antibodies release proteins called complement system which punches holes in pathogens thus killing them Internal Pathogens are eliminated by All nucleated cells have MHC class I Cytotoxic T cells recognize Class I bc they are CD8 They attach to infected cells and send chemicals to destroy the cell by apoptosis Memory Cells both B and T cells create these daughter cells Secondary immune response is much faster and larger Vaccines teach immunological memory to your body by giving weakened or altered pathogens to the body o Vaccine Types Subunit isolated viral proteins Attenuated live viruses that have been made harmless Inactivated damaged by chemical treatments by losing their ability to rapidly grow Allergies overreactions to foreign substances allergens cause the IgE antibody class to be made not antigens Sensitized cells bind to allergen the second time it is introduced to the body and recruit histamine and cytokines Anaphylactic shock can result Autoimmune diseases immune responses against molecules cells that normally exist in the host Destruction of the body s own cells and structures Multiple sclerosis cytotoxic t cells attack myelin sheath resulting in Rheumatoid arthritis antibodies alter the lining of joints causing Type 1 diabetes cytotoxic t cells attack insulin secreting cells in coordination problems painful inflammation pancreas Hygiene hypothesis overreactions are due to the lack of exposure to pathogens immune system never gets to act as it
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