Infectious%20Disease%20and%20the%20Immune%20System

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Infectious Disease and the Immune System
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Viruses

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

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Viruses

• 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

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Viruses

• Virus types
• DNA viruses.
• RNA viruses.

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Viruses

• Retroviruses
• RNA core.
• Must contain an enzyme called reverse
  transcriptase.
• RNA reverse transcriptase--DNAinserts into
  host cells DNAhost cells ribsomes make
  mRNAProteins are part of new viruses

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Viroids Prions

• Viroids
• Naked RNA that can replicate.
• Prions
• Infectious proteins.
• Disrupt the cells activities.

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Polio virus
Influenza Virus
Ebola
Rabies
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Bacteria

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

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Plasmids

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

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Bacteria

• 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.

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Nonspecific Defenses
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Nonspecific Defenses

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

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Identifying Pathogens

• 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.

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Physical Barriers to Disease

• Nonspecific defense.
• Sweat, oils, waxes.
• Mucous membranes.
• HCL of stomach.

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Fever

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

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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

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Inflammatory Response

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

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Inflammatory Response

• Symptoms
• Redness
• Heat
• Swelling pain

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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

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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)

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Non specific Cellular Defense

• Macrophages- another type of phagocyte
• Stationed in certain tissues.
• Destroy by phagocytosis.
• Rid the body of debris and damaged cells.

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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.

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Day 3 Immune system and recognition of pathogens
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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.

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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.

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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
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Immune System Organs

• Thymus gland
• Spleen
• Bone marrow
• Lymph nodes
• Lymphocytes
• B cells
• T cells (helper, cytotoxic)

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Immune Responsehow antigens are 1st 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

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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.

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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.
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Antibody Mediated Immune System

• Plasma cells produce proteins called antibodies.
• Antibodies recognize and attach to pathogen.
• Antibodies are Y-shaped proteins.

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Antibody Mediated Immune System

• The two arms of the antibody are identical.
• Antibodies match proteins of pathogen.
• Actions of antibodies.

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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.

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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.

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Brain Pop

• http//glencoe.mcgraw-hill.com/sites/dl/free/00786
  95104/161752/00051106.html
• Immune System ?
• http//glencoe.mcgraw-hill.com/sites/dl/free/00786
  95104/164155/00044676.html
• Bacteria ?