Physio Study Guide 4

Physio Study Guide 4 - Mechanisms of Acquired Immunity The...

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Mechanisms of Acquired Immunity The mechanisms of acquired immunity (specific and needs time to be activated for highly specific response). Function depend critically on specificity of receptors on T and B lymphocytes and the antibodies that the b-cells secrete. Antibodies: plasma-clotting factor= serum. The most abundent protein in this is Albumen, and most proteins are globular proteins. Abbreviated A. The rest of the serum proteins are called globulins. The rest of the globulins are alpha 1, alpha 2: on basis of size. In these classes of serum proteins are all the plasma proteins that matter: hormones, complement. The antibodies are in the gamma globulin class. Immunoglobulin is a specific name for antibodies of gamma class. Within the immunoglobulins there are 5 different classes. IGM, IGG, IGE, IGA, IGD all are secretory products from b-lymphocytes. The most abundant in plasma are IgG followed by IgM. IgE minor component of plasma and most of it binds to something else; not really in plasma IgA an antibody that is not very abundant. IgD: membrane protein Structure All have same kind of y-shape. This is the basic structure that is shared. 2 different types of chains: 2 heavy chains and 2 light chains. Yellow line are disulfide bridges that covalently hold structures together. Each has a variable region where amino acid sequence from cell to cell is highly variable and invariable C structure. All of the antibodies by a single b-cell will be identical in this structure. From B-cell to B-cell, different B-cells will secrete different antibodies. Fab and FC digest with proteolitic enzymes, it cleaves it at the hinge reason (heavy chain is flexible here); allows for the binding site to orient differently. Solubility much more effective because of this property. End up with 2 fragments Fab (antibody binding) with variable region where antibody binds to antigen. Fc is crystalizable portion because the mixture of antibodies have the same structure. Handy to use Fad to bind to things without provoking the entire immune response. 1
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IgD same basic structure: transmembrane protein made by B-cells and expressed in low concentrations on b-cell membrane where it serves as a receptor. Its role in activating B-cells is not very well understood. IgD and IgM are both plasma membrane receptors. B-cells express IgD and IgM on surface. When a b-cell is activated: antigen binds to receptor: b-cell then will undergo clonal expansion and some will become memory cells, and the majority will become plasma cells and begin to secrete antibodies. The first type of antibody secreted by an activated by an activated b cell is always IgM. IgM is a big molecule of 5 subunits and Jchain. Large molecule, 10 binding sites,
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Physio Study Guide 4 - Mechanisms of Acquired Immunity The...

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