Zoology 101: Animal Biology Last Lecture Outline Lecture 30 1. Lymphatic system2. Adaptive immunityCurrent lecture 1. B/T cells and clonal selection2. Antibody function B/T cells and clonal selection• Activated B/T cells undergo clonal selection◦ antigens only bind to the B cells with complementary antigen receptor ◦ selected B cell proliferates or forms clones (clones have same antigen receptor)◦ Some clones (daughter cells) develop into long lived memory cells; others develop into plasma (effector) cells and are short lived • Immunological memory responsible for long term protection against diseases ◦ repeated exposure → faster response, greater magnitude of response Anitbody function• Do not kill pathogens → mark for destruction • Neutralization: prevent infection to host cells • Opsonization: create target for phagocytosis• Activation of complement system and pore formation → leads to lysis • Allergies are exaggerated (hypersensitive) responses to antigens◦ Antibodies are produced after first exposure to an allergen and they attach to receptors on mast cells ◦ on subsequent exposure the allergen binds to mast cell- associated antibody molecule ◦ Mast cells release histamine which leads to typical allergy symptoms • Autoimmune diseases: when the immune system loses tolerance for itself and turns against certain molecules of the body ◦ Grave's disease: ▪ Antibodies mimic TSH which stimulate excess thyroid hormones ◦ Rheumatoid arthritis ◦ Insulin dependent diabetes mellitus (Type 1 diabetes) ▪ Autoimmune destruction of Beta cells ◦ Multiple sclerosis ▪ Degenerative disease attacking CNS▪ T cell mistakes myelin on neuron as a foreign body and attacks it ▪ Destroyed/damaged myelin leaves multiple scarring → sclerosis ▪ nerve signals slowed or blocked → MS
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