Chapter 11 – Elements of Host Protective Responses Medical Microbiology Chapter 11 – Elements of Host Protective Responses

Our Defense Systems Our body has 3 layers/walls of defense against pathogens and toxins 1st = barriers 2nd = innate responses 3rd = antigen-specific immune responses My Analogy

Barriers Barriers Skin Mucous membranes Secretions Normal flora lactic acid and fatty acids (skin) mucus: filter for respiratory system, etc. Tears, lysozyme, stomach acid Normal flora

Innate Responses Innate Responses – they are always present and ready to go. Complement Proteins Neutrophils and Macrophages Natural Killer cells

Ag-specific Responses Must be produced after infection (usually takes 5-7 days) Activated B-cells produce Antibodies Activated T-cells attack and destroy infected cells and cancer cells

Players in Defense Chemicals (allow communication between cells): Cytokines – stimulate and regulate the immune response Interferons – anti-viral proteins, stimulate immune response Chemokines – involved with the inflammatory response They lead to chemotaxis and activation

Players in Defense Table 11-1 Cells (carry out the actual defense): Table 11-2 and Figure 11-1 Some are designated by CD “Clusters of Differentiation” MHC I – found on all nucleated cells MHC II – found on antigen-presenting cells (APCs)

Players in Defense Blood cells of defense – Table 11-3

The Lymphatic System Functions: Return tissue fluid to the blood stream Why is this necessary? Example (~30L out of capillaries, 27L in) Fat transportation Immunity – defense against pathogens and other foreign material

Lymphatic Vessels Lymph capillaries – pick up interstitial fluid Lymph vessels – have one-way valves like the veins Lymph is dumped back into the blood Figures from other text

Lymphatic Vessels As the lymph travels back to the blood stream it passes through many lymph nodes Figures

Lymph Nodes Function as filtering stations for the lymph Macrophages are in the lymph nodes What do they do? B-cells and T-cells are also in the lymph nodes Swollen lymph nodes

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Lymph Nodules and Tonsils No lymph filtering Tonsils are accumulations of lymph nodules Function? swollen tonsils are a sign of a throat infection Figure

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Spleen The spleen is the filtering site for the blood Dead RBCs Figure

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