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Transcript
Infectious Disease and the Immune System KOCH’S Postulates 1. Pathogen must occur in body of organism with the disease. 2. Pathogen should be isolated and grown in culture. 3. Inoculated animal should develop the disease. 4. Same pathogen should be grown in culture. Modern Biology Pages 954-958 Viruses • Viruses are nonliving. • Only characteristic of living organisms is ability to reproduce. Modern Biology Pages 486-490 Viruses • Viruses are composed of; – a protein – DNA or RNA molecule. Modern Biology Pages 486-490 Viruses • Viruses are composed of; – a protein called a capsid. – DNA or RNA molecule. – Some viruses have a membrane like structure called a envelope. Modern Biology Pages 486-490 Viruses • Virus types: – DNA viruses. – RNA viruses. Modern Biology Pages 486-490 Viruses • Retroviruses – RNA core. – Must contain an enzyme called reverse transcriptase. – RNA --DNA-mRNA--Protein. Modern Biology Pages 486-490 Plasma Membrane • Contains – Transmembrane proteins. • Channels • Carriers – Surface proteins. • Glycoproteins. – Cholesterol molecules HIV & Plasma Membrane • HIV recognizes CD4 (part of T lymphocytes) protein on cell surface. • Gains entry & creates DNA molecule. • DNA becomes part of cell’s DNA. • Makes more viruses. Glycoprotein Viroids & Prions • Viroids: – Naked RNA that can replicate. • Prions: – Infectious proteins. – Disrupt the cells activities. Modern Biology Pages 486-490 Polio virus Influenza Virus Ebola Rabies Bacteria • Prokaryotic cells. • Always single cell. • Composed of: – Cell wall – Cell membrane – Cytoplasm. Modern Biology Pages 474-477 Bacteria • Some bacteria have a capsule. – Composed of polysaccharides. – Protects bacteria from WBCs. • Bacteria have short hair like structures called pili. Modern Biology Pages 474-477 Infectious Disease and the Immune System What is a pathogen? • A pathogen is anything that causes disease. – – – – – – Bacteria Protist Virus Retro-virus Fungus prion Modern Biology Pages 956-957 How does the body recognize pathogens? • Most pathogens have proteins. – Called antigens. – Body’s cells have MHCs – “Act as off campus I.D. cards”. – Wrong MHC – engulf and destroy! Modern Biology Pages 956-957 What are nonspecific defenses? • Resistance is your bodies ability to defend against pathogens. • Your immune system gives you resistance. Modern Biology Pages 954-958 What are physical barriers to disease? • Nonspecific defense. – Sweat, oils, & waxes. – Mucous membranes. – HCL of stomach. Modern Biology Pages 954-958 Why do you get a fever? • • • Pathogens that attack human body like 98.6 F. best. Raising temperature of body increases effectiveness of WBC’s. Decreases effectiveness of pathogen. Modern Biology Pages 954-958 Interferon • • Chemical released by cells infected by viruses. Causes surrounding cells to resist infection. Modern Biology Pages 954-958 Inflammatory Response • Inflammatory response occurs when pathogen penetrates the skin. Modern Biology Pages 954-958 Inflammatory Response • Symptoms: – Redness – Heat – Swelling pain Pages 954-958 Inflammatory Response • What occurs: – Damaged cells release histamines. – Causes vasodialation – Causes increase in permeability. Pages 954-958 Non specific Cellular Defense • Neutrophils – – – – – Most common Kill pathogens using phagocytosis. Circulate in blood stream. Migrate towards site of infection. (chemotaxis) Move out of the blood stream (emmigration) Pages 954-958 Non specific Cellular Defense • Macrophages – Stationed in certain tissues. – Destroy by phagocytosis. – Rid the body of debris and damaged cells. Wednesday 5/21/2003 Pages 954-958 Non specific Cellular Defense • Natural Killer Cells – Attack cells which have been infected by pathogen. – Kills cancer cells. – Kills by puncturing cell membrane. Wednesday 5/21/2003 Pages 954-958 Wednesday 5/21/2003 Pages 954-958 How WBCs Recognize Pathogens • • • • All of your cells are marked as “self” by proteins. (MHCs) Nonspecific WBCs recognize your proteins. They leave these cells alone. Any cell that does not have MHCs is attacked. Pages 954-958 Summary of Immune System To Date: • Body has different “lines of defense”. – Barriers • Skin, mucous membranes, secretions. – Non specific defenses. • Macrophages, neutrophils, natural killer cells. • Interferon, compliment. – Specific defenses. Specific Defenses Pages 959-964 • If pathogens enter the body the immune system responds. • Response is to specific pathogens. (Single type) RBC of different blood type has antigens Immune System Organs • • • • • • Thymus gland Spleen Bone marrow Lymph nodes B cells T cells. Pages 959-964 How Antigens are Recognized • • • Pathogen has proteins (antigens) on its surface. Macrophages destroy pathogen. Macrophages present parts of the pathogen (antigen) to the lymphocytes. Pages 959-964 How Antigens are Recognized • Lymphocytes then remember the antigen. • Attack and destroy if in body. • Cell mediated immune response. Pages 959-964 Cell Mediated Immune System • T cells directly attack and destroy antigen. • B cells produce antibodies that recognize antigen. Bacteria adhering to T lymphocyte. Pages 959-964 Antibody Mediated Immune System • Macrophages present portion of pathogen to B Lymphocytes. • Lymphocytes learn pathogen structure and divide into plasma cells. Pages 962-965 Antibody Mediated Immune System • Plasma cells produce proteins called antibodies. • Antibodies recognize and attach to pathogen. • Antibodies are Yshaped proteins. Pages 962-965 Antibody Mediated Immune System • • • • The two arms of the antibody are identical, but ends are different. Antibodies match proteins of pathogen. Actions of antibodies. Pages 962-965 Antibody Mediated Immune System • Primary response occurs the first time exposure to pathogen occurs. • Secondary response occurs when pathogen invades again. – – – Faster reaction. Stronger reaction. Memory B cells. Pages 962-965 Immunity & Vaccination • Naturally acquired active immunity. • Naturally acquired passive immunity. • Artificially acquired active immunity. • Artificially acquired passive immunity. – – – – – Your are exposed to pathogen in everyday life. Breast milk. Mom’s antibodies prior to to birth. Vaccination. You are given a shot of antibodies. Pages 962-965