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N5315 Advanced PathophysiologyInflammation, Altered Immunity and Infection Immune System1.Each individual T or B cell recognizes only 1 particular antigen but sum of population of lymphocytes may represent millions of foreign antigens. Occurs in specialized (primary) lymphoid organs (thymus/bone marrow) > passes through these tissues, lymphocytes mature and undergo changes that commits to being either T or B cell > released into circulation when lymphocyte immature & have capacity to react with antigen (immunocompetent)Remain dormant until antigen initiates 2ndphase of immune response > clonal selection > to initiate response- most antigens must be “processed & presented” because they cannot react directly with cells of immune system = APCs (antigen presenting cells)2.Describe how the normal function of T-lymphocyte and B-lymphocyte cells differ. T-lymphocyte: (mature in thymus) provide weapons to act antigens. Some kill virus-infected cells directly, some help B-cells make antibodies which circulate to bind to antigens (4 types)B-lymphocyte: (mature in bone marrow) With help of T cells, B-cells make Y shaped proteins called antibodies that stick to antigens on the surface, stopping them and then creating clumps that alert your body to the presence of intruders. Your body then starts to make toxic substances to fight them. Phagocytes engulf and then destroy antibody-covered antigens3.Differentiate between function of humoral and cell mediated immunity and describe the implications for practice. Humoral immunity: Immunity conferred by B cells (provides immunity against some viral infections, toxin induced diseases, diseases caused by pneumococci, meningococci, haemophilius)oB cells: mature into plasma cells that then produce antibodies (5 classes of antibodies- glycoproteins)Cell mediated immunity: Immunity conferred by T cells (active against cells infected with intracellular bacteria/viruses). oDefends against: fungal infections, parasitic infections, tumors, responsible for organ transplantation rejectionoT cells differentiated (named) by expression of antigens on their cell membrane called “cluster of differentiation”4.Describe the difference between active acquired immunity and passive acquired immunity and theimplications for health promotion. Active acquired immunity: Adaptive. 3rdline of defenseoState of immunity obtained after natural exposure to an antigen or after immunization(improves with repeat exposure)oSlower acting, specific, long livedPassive acquired immunity: Via transfer of antibodies (T cells) to the recipient- doesn’t involve the host’s immune response at all oNatural passive immunity: Mother to fetus (cross placenta/breast milk)oArtificial passive immunity: Occurs when antibodies are given to a recipient to provide immunity (Used to tx: rabies, tetanus, hepatitis, snake bites) Unvaccinated individual who are exposed to particular agents (hep A, rabies virus) are given immunoglobulins that are prepared form individuals who already have antibodies against particular pathogen
*Good way to fight infection, immediate protection, immunity only lasts as long as the antibodies (~2 weeks) > T cells are eventually destroyed