52 Pathogens & Innate Immunity

52 Pathogens & Innate Immunity - PSL302Y1Y Lecture...

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Pathogens & Innate Immunity Outline - What does our immune system do? - What kinds of pathogens are there? - How do we defend against pathogens? - What are the components of the immune system? - How does the innate immune system work? Textbook reading: 783-793 (5E), 777-787 (4E) 1. What does our immune system do? - Destroys pathogens (foreign organisms) - Detects & kills abnormal cells (virally infected/cancerous host cells) - Remove cell debris from body (formed by apoptosis) 2. What kinds of pathogens are there? - Extracellular: - Parasitic worms: live in GI tract or bloodstream - Fungi: i.e. Candida albicans infects mouth, throat & reproductive tract - Protozoa: i.e. Bucanizoa causes sleeping sicking - Bacteria - Intracellular: - Bacteria & protozoa (i.e. Malaria) - Viruses: smallest pathogens; require hosts to reproduce Viruses : require host cells to replicate - Contain nucleic acids (DNA or RNA) & protein coat (used to bind & enter cell) - DNA/RNA replicated by hijacking cell replicating machinery - Codes for viral proteins: host cells synthesize them (coat) - Virus either bursts from cell (destroying it) or buds off = infect! - Unique challenge for immune system to detect virally infected cells from normal cells 3. How do we defend against pathogens? - Physical barriers castle - Skin, mucous, acid, lysozyme - Immediate, non-speci±c - Innate immunity guards - Cells & chemicals in body ²uids - Rapid, non-speci±c - Acquired immunity army - Lymphocytes (B & T cells) - Slower, very speci±c - Innate & acquired immunity can interact PSL302Y1Y: Lecture 52, by French Wed., Feb. 16, 2011 1 of 6
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4. What are the components of the immune system? Components - Lymph : tissue fuid - Encapsulated lymphoid tissue - Lymph nodes: Flter lymph; resident immune cells attack pathogens & ±oreign debris - 500-600 in body: ±ound superFcially & mostly in neck, groin, under arms - Spleen - Diffuse lymphoid tissue: - Gut-associated lymphoid tissue - Lymphocyte pdc° at: - Thymus: in neck; shrinks w/ age = produces T lymphocytes - Bone marrow: produces most blood cells (incl. WBCs) Lymphatics: ²xns 1) Return excess tissue fuid to the blood 2) Transport pathogens to lymph nodes ( contain dendritic cells , which are phagocytic) 3) Transport fat ±rom digestive system to the blood Specialized lymphoid organs Lymph node: - Lymphatics drain into lymph node - Vascularized: pathogens can come ±rom blood Spleen: - Well vascularized:
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52 Pathogens & Innate Immunity - PSL302Y1Y Lecture...

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