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Infectious Disease and the Immune System. Viruses Viruses are non- living. Only characteristic of living organisms is ability to reproduce. Obligate intracellular.

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Presentation on theme: "Infectious Disease and the Immune System. Viruses Viruses are non- living. Only characteristic of living organisms is ability to reproduce. Obligate intracellular."— Presentation transcript:

1 Infectious Disease and the Immune System

2 Viruses Viruses are non- living. Only characteristic of living organisms is ability to reproduce. Obligate intracellular parasites.

3 Viruses are composed of; – a nucleic acid- can be dna OR rna. –Protein coat called a capsid which can be different shapes; helical, polyhedral –Some viruses have an envelope of lipids that surround the capsid when they leave a host cell Viruses

4 Virus types: –DNA viruses. –RNA viruses. Viruses

5 Retroviruses –RNA core. –Must contain an enzyme called reverse transcriptase. –RNA + reverse transcriptase--DNA inserts into host cells DNAhost cells ribsomes make mRNAProteins are part of new viruses Viruses

6 Viroids: –Naked RNA that can replicate. Prions: –Infectious proteins. –Disrupt the cells activities. Viroids & Prions

7 Polio virus Influenza Virus Ebola Rabies

8 Bacteria Prokaryotic cells. Always single cell. Composed of: –Cell wall –Cell membrane –Cytoplasm. –DNA that is a single closed loop –NO membrane bound organelles

9 Plasmids Some bacteria have a secondary genome called a plasmid. Small self replicating DNA that cause disease or make the bacteria resistant to antibiotics

10 Some bacteria have a capsule. –Composed of polysaccharides. –Protects bacteria from WBCs. Bacteria have short hair like structures called pili for connecting to each other and to hosts. Bacteria

11 Nonspecific Defenses

12 Pathogens are disease causing agents. Resistance is your bodies ability to defend against pathogens. Your immune system gives you resistance.

13 Kochs Postulates Pathogen must occur in body of organism with the disease. Pathogen should be isolated and grown in culture. Inoculated animal should develop the disease. Same pathogen should be grown in culture. Identifying Pathogens

14 Physical Barriers to Disease Nonspecific defense. –Sweat, oils, & waxes. –Mucous membranes. –HCL of stomach.

15 Fever Pathogens that attack human body like 98.6 f. best. Hypothalamus raising temperature of body increases effectiveness of WBCs. Decreases effectiveness of pathogen.

16 Proteins Interferons –Chemical released by cells infected by viruses. –Causes surrounding cells to resist infection. Complement Proteins –Circulate in your blood and become active when they encounter certain pathogens

17 Inflammatory Response Inflammatory response occurs when pathogen penetrates the skin. Nonspecific- any pathogen causes an inflammatory response if your skin is broken

18 Inflammatory Response Symptoms: –Redness –Heat –Swelling pain

19 Inflammatory Response What occurs: –Damaged cells release histamines. –Causes increase in permeability. –Causes vasodialation (swelling) –Allows phagocytes to digest and destroy foreign matter. –Phagocytes are drawn towards histamine

20 Non specific Cellular Defense Neutrophils –Most common phagocyte –Kill pathogens using phagocytosis. –Circulate in blood stream. –Migrate towards site of infection. (chemotaxis) –Move out of the blood stream (emmigration)

21 Non specific Cellular Defense Macrophages- another type of phagocyte –Stationed in certain tissues. –Destroy by phagocytosis. –Rid the body of debris and damaged cells.

22 Non specific Cellular Defense Natural Killer Cells Cytotoxic T Cells –Attack cells which have been infected by pathogen. –Kills cancer cells. –Kills by puncturing cell membrane.

23 Day 3 Immune system and recognition of pathogens

24 How WBCs Recognize Pathogens All of your cells are marked as self by proteins in your cell membrane. Nonspecific WBCs recognize your proteins. They leave these cells alone. Any cell that does not have self markers are attacked.

25 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 proteins. –Specific defenses.

26 Specific Defenses If pathogens enter the body, the immune system responds. Response is to specific pathogens. (Single type) RBC of different blood type has antigens

27 Immune System Organs Thymus gland Spleen Bone marrow Lymph nodes Lymphocytes –B cells –T cells (helper, cytotoxic)

28 Immune Response how antigens are 1 st recognized by lymphocytes- cell mediated response Pathogen has proteins (antigens) on its surface. Macrophages destroy pathogen. Macrophages present parts of the pathogen (antigen) to helper T cells. Macrophages release interleukins Interleukins cause –Cytotoxic Killer T cells to destroy infected cell –Creation of B cells

29 How Antigens are Recognized Lymphocytes then remember the antigen. Attack and destroy if in body. Cell mediated immune response. Antibody and cell mediated immune response are happening at the same time in the body.

30 Cell Mediated Immune System Macrophages present portion of pathogen to B Lymphocyte cells. B cells learn pathogen structure and divide into plasma cells and memory cells Antibodies are made Bacteria adhering to T lymphocyte.


32 Antibody Mediated Immune System Plasma cells produce proteins called antibodies. Antibodies recognize and attach to pathogen. Antibodies are Y- shaped proteins.

33 Antibody Mediated Immune System The two arms of the antibody are identical. Antibodies match proteins of pathogen. Actions of antibodies.

34 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.

35 Immunity & Vaccination Naturally acquired active immunity. –Your are exposed to pathogen in everyday life. Naturally acquired passive immunity. –Breast milk. –Moms antibodies prior to to birth. Artificially acquired active immunity. –Vaccination. Artificially acquired passive immunity. –You are given a shot of antibodies.

36 Brain Pop /161752/ htmlhttp://glencoe.mcgraw- /161752/ html Immune System /164155/ htmlhttp://glencoe.mcgraw- /164155/ html Bacteria

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