Biochemistry & Immunology in Nursing (NRS414) Past Paper PDF

27/12/2024 2 BIOCHEMISTRY & IMMUNOLOGY LEARNING OBJECTIVES IN NURSING (NRS414) AT THE END OF THE LESSON, STUDENTS ARE ABLE TO EXPLAIN OR ID...

27/12/2024 2 BIOCHEMISTRY & IMMUNOLOGY LEARNING OBJECTIVES IN NURSING (NRS414) AT THE END OF THE LESSON, STUDENTS ARE ABLE TO EXPLAIN OR IDENTIFY: I. Adaptive immunity : humoral and cellular-mediated. II. Components of lymphoid systems. III. Nature of antibodies. IV. Reactions of antigen-antibody binding. NRS421 HS240 HS260 3 4 5 6 1  27/12/2024 7 8 9 10 Adaptive Immune Response First response to particular antigen called primary response May take a week or more to develop Immune system remembers pathogen on subsequent exposure Termed secondary response Adaptive immunity divided into: Humoral immunity Eliminates extracellular pathogens Cellular immunity Eliminates intracellular pathogens 11 12 Adaptive Immune Response Lymphocytes (B and T) Humoral Immunity Cell Mediated Immunity B cells T cells Production of Occurs at cellular level Antibodies Antigens are embedded in cell membranes or are inside cells. Antibodies are inaccessible to those sites 2  27/12/2024 13 14 Humoral Immunity Mediated by B lymphocytes B-cell receptor Develops in bone marrow B cells are triggered by antigen to proliferate into plasma cells Plasma cells produce antibodies Antibodies produced when antigen bind to B cell receptor Some B cells produce memory cells 15 16 Dendritic cells Dendritic cells (DCs) are antigen-presenting cells (also known as accessory cells) of the mammalian immune system. Their main function is to process antigen material and present it on the cell surface to the T cells of the immune system. They act as messengers between the innate and the adaptive immune systems. 17 18 Cellular Immunity Anatomy of the Lymphoid System Lymphoid system is a collection of tissues and Mediated by T lymphocytes (T cells) organs designed to bring B and T cells in contact Matures in thymus with antigens In order for body to mount appropriate response, Divided into 2 subsets immune cells must encounter antigen  Cytotoxic T cells (TC) Lymphoid system includes Lymphatic vessels – carry a fluid - lymph  Helper T cells TH Secondary lymphoid organs – ex : lymph nodes, spleen, tonsils T cell receptors help with antigen Primary lymphoid organs – bone marrow and thymus recognition 3  27/12/2024 19 20 21 22 Anatomy of the Lymphoid System Primary lymphoid organs Bone marrow and thymus are primary lymphoid organs Location where stem cells destined to become B and T cells B cells mature in bone marrow T cells mature in thymus Once mature, cells leave primary lymphoid organs and migrate to secondary lymphoid organs 23 24 Nature of Antigens Antigen and Antigenic determinant (Epitope) Coined from compounds that elicit (produce) antibody production Most antigens are large protein molecules Antibody generator with complex structures. Antigen – any molecule that react with Antigens : Mw > 10,000 antibody or an antigen receptor on a lymphocyte. Some are polysaccharides, few are Proteins and polysaccharides induce string glycoprotein (carbohydrate + protein) response Epitope : Areas on a cell to which antibodies Lipids and nucleic acids often do not can bind. Recognition of antigen directed at antigenic determinant or epitope 4  27/12/2024 25 26 Antigen https://youtu.be/sJptG3_uiVg Antibodies Binding to Epitopes on a Bacterial Cell 27 28 NATURE OF ANTIBODIES Structure of the Ab Basic unit is the monomer Made of four chains of amino acids held Disulfide together by disulfide bonds bonds Two chains are heavy Two chains are light Each heavy and light chain has a constant region The constant region is known as Fc region Basic Structure of an Antibody Molecule (a) The Y-shaped molecule; the arms of Each heavy and light chain has a variable the Y make up the Fab regions, and the stem is the Fc region. (b) The molecule is region made up of two identical heavy chains and two identical light chains. Disulfide bonds join the two chains as well as the two halves of the molecule. The constant Variable region is unique to each Ab region is made up of the regions depicted in shades of red. The variable regions differ among antibody molecules, and account for the antigen-binding specificity of This region binds to a specific Ag and is antibody molecules. known as “Fab” region Fc = crystallize fragment Fab = antigen-antibody binding fragment 29 30 Reactions of Antibody-Antigen binding 1. Neutralization A toxin or virus coated with antibodies Antibody Prevents toxin from interacting with cell https://youtu.be/uvlah0Qensg 5  27/12/2024 31 32 3. Agglutination and precipitation 2. Immobilization and prevention of adherence Binding of antibodies to multiple molecules of antigen produce large Antibody bonding to cellular structures (flagella and antigen-antibody complexes. Single antibody molecules can bind to adjacent antigens and form network. pili) to interfere with function (motility and attachment) Bacteria more easily phagocytized. In a laboratory test - Clumping of bacterial cells by specific antibody can be seen as agglutination or precipitation. 33 34 4. Opsonization Coating of bacteria with antibody to enhance phagocytosis 6. Antibody-dependent Cellular Cytotoxicity 5. Complement activation Multiple antibodies bind a cell which becomes target for Antibody bonding triggers classical pathway destruction of certain cells ex : NK cells NK cells attach to the fragment crystallizable (Fc) regions of antibodies and release compounds directly to kill the cells. 35 36 Immunoglobulin Classes Antibodies (Ab) divided into five classes Antibody-Antigen Binding Class is based on constant region of the Ab https://youtu.be/N3L4kQqsGPQ Classes include: https://youtu.be/3W67OH3v2lU IgG IgA https://youtu.be/Ew15yHuqzmY IgM IgE IgD 6  27/12/2024 37 38 IgM First Ab to respond to infection – secreted into the blood in primary response. High levels indicate recent infection. IgM binds to antigen – activates complement – microorganisms clump 5 – 13% of Ab in circulation Structure: pentamer Five monomer units joined together at the constant region Found on the surface of B lymphocytes as a monomer Only Ab that can be formed by the fetus, unable to cross the placenta 39 40 IgD IgG Found in B cell membranes Dominant Ab in circulation (blood) 80 – 85% Ab in circulation Rarely secreted,