Chapter 39 Immunity from Disease

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Chapter 39Immunity from Disease
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39.1 The Nature of Disease

• Disease a change that disrupts the homeostasis
  in the body
• Pathogen disease-producing agent
• Ex. Bacteria, fungi, viruses, parasites
• source soil, contaminated water infected
  animals (including humans)
• Infectious Disease any disease caused by the
  presence of pathogens

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Pathogens
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39.1 The Nature of Disease

• In order to spread infectious disease there must
  be a continual source of disease causing
  organisms
• Reservoirs of pathogens
• People
• Animals
• Non-living

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39.1 The Nature of Disease

• Reservoirs of Pathogens People
• Main source of human disease is human body
• Carriers harboring pathogens without exhibiting
  any signs of illness
• Incubation period symptom-free period when
  pathogens are multiplying in body
• Unknowingly pass on disease in first stages
  before symptoms appear.

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39.1 The Nature of Disease

• Reservoirs of pathogens Animals
• Diseases passed to humans from animals, usually
  from bites
• Ex. Rabies, Lyme Disease, malaria
• Reservoirs of pathogens non-living
• Soil contaminated water

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39.1 The Nature of Disease

• Transmission of Disease
• Direct contact exchange of bodily fluids
• Object pathogen present on non-living object
  (money, toys, towels) transmitted by handling
  contaminated objects

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39.1 The Nature of Disease

• Transmission of Disease
• Airborne cough or sneeze pathogens are in
  droplets of mucus and spread into air
• Vectors insects other arthropods bites from
  mosquitoes, ticks, flies

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39.1 The Nature of Disease

• Symptoms of Disease
• If pathogen overcomes bodys defense system, it
  multiplies causing damage to invaded tissues
• Bacteria produce toxins (poisonous substances)
  that inhibit protein synthesis, destroy blood
  vessels or cause disruption of nervous system
• Viruses take over host cells genetic metabolic
  machinery causing death of host cell

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39.1 The Nature of Disease

• Treating Disease
• Antibiotics produced by microorganisms that
  will kill or inhibit growth and reproduction of
  bacteria
• NO EFFECT ON VIRUSES
• antibiotic use and overuse
• antibiotics work only on bacteria
• kill bacteria w/out harming other cells
• most interfere with bacterial structures (cell
  walls or metabolic processes) not present in
  human cells

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39.2 Defense Against Infectious Disease

• Prevention
• Best way to fight disease is avoid it
• simple measures often very effective, such as
  wash hands, cover mouth when cough, etc.
• if prevention fails, bodies have a system
  designed to defend against disease immune
  system

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39.2 Defense Against Infectious Disease

• Non-specific Innate Immunity
• Earliest line of defense
• Defends against any and all pathogens
• Skin body secretions

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39.2 Defense Against Infectious Disease
The bodys first line of defense the 1st barrier
a pathogen must penetrate is the skin
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39.2 Defense Against Infectious Disease

• If pathogen gets past skin, next line is mucus

• Main function of mucus is to prevent areas from
  drying out.
• Also traps microorganisms that might enter
  respiratory or digestive tract

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39.2 Defense Against Infectious Disease

• Sweat, tears, saliva
• Contain enzyme lysozyme that breaks down cell
  wall of bacteria

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39.2 Defense Against Infectious Disease

• Inflammatory Response
• 2nd line of defense non-specific
• After bacteria has entered damaged body tissue
• Symptoms redness, swelling, pain, heat

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39.2 Defense Against Infectious Disease

• Steps of inflammatory response

3. Histamine causes blood vessels in area to
dilate redness

• Cells are damaged

4. Fluid leaked from vessels help destroy toxic
agents swelling, pain temp inc.
2. Damaged cells and white blood cells release
histamine
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39.2 Defense Against Infectious Disease

• Phagocytosis of pathogens
• Phagocytosis cells engulfing particles
• Phagocytes white blood cells that destroy
  pathogens by surrounding engulfing them

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39.2 Defense Against Infectious Disease

• Types of Phagocytes
• Macrophages consume pathogens and dead
  neutrophils
• Neutrophils - After leaving nearby blood vessels,
  these cells recognize chemicals produced by
  bacteria in a cut or scratch and migrate "toward
  the smell".

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Seek Destroy
Phagocytosis
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39.2 Defense Against Infectious Disease

• Protection against Viruses
• To engulf virus, phagocyte would engulf host
  cell, then be destroyed itself if virus
  multiplies within phagocyte
• Counteract viral infection with Interferon-
  protein that protects cells from viruses
• Produced by infected body cell, diffuses to
  nearby uninfected cells produces antiviral
  proteins to prevent virus from multiplying

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39.2 Defense Against Infectious Disease

• Acquired Immunity
• Defense against a specific pathogen
• White blood cells develop the ability to
  recognize a specific foreign substance
• Antigen proteins on surface of foreign substance
  recognized by body as non-self
• Stimulate an immune response
• Immune Response body recognizes antigens and
  responds by producing antibodies against it

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39.2 Defense Against Infectious Disease

• Antibody Immunity
• Players-
• Helper T Cells activates B cells
• B Cells produce antibodies
• Plasma Cells release antibodies
• Memory B cells- remain in blood stream ready and
  armed to respond rapidly to another invasion by
  same pathogen

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39.2 Defense Against Infectious Disease

• Steps of antibody Immunity after 1st exposure to
  pathogen
• Step 1 pathogen enters tissue through wound
• Step 2 pathogen is attacked by macrophage at
  infection site

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39.2 Defense Against Infectious Disease

• Step 3 antigens of pathogen displayed on
  surface of macrophage
• Step 4- Helper T cells receptor site recognizes
  binds to antigen on macrophage

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39.2 Defense Against Infectious Disease

• Step 5 helper T cell stimulates B cell to
  become plasma cell and release antibodies to
  inactivate or destroy pathogen
• Step 6 Some B cells remain as memory cells
• Step 7- antibodies memory cells remain in blood
  to respond immediately to next invasion

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39.2 Defense Against Infectious Disease
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39.2 Defense Against Infectious Disease

• Cellular Immunity
• T cell involved is killer T cell (cytotoxic T
  cell) do not form antibodies
• Fights protozoa and parasites
• Responsible for tissue rejection in transplants

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39.2 Defense Against Infectious Disease

• Steps of cellular immunity
• 1 pathogen engulfed by macrophage
• 2 antigens displayed on macrophage stimulate
  helper T cell
• 3 helper T stimulates killer T cell
• 4 killer T attacks infected cell releasing
  enzymes directly into pathogen causing it to lyse
  and die

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39.2 Defense Against Infectious Disease
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39.2 Defense Against Infectious Disease

• Passive Active Immunity
• Passive develops as a result of acquiring
  antibodies that are generated in another host
• Natural antibodies transferred from mother to
  unborn baby or through mothers milk
• Artificial injecting antibodies that come from
  animal or human that is already immune

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39.2 Defense Against Infectious Disease

• Active develops when body is directly exposed to
  antigens and produces antibodies in response
• Natural person is exposed to antigen, produces
  antibodies is immune to next exposure
• Artificial vaccine substance consisting of
  weakened, dead or incomplete portions of pathogens

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Defenses of the Human Immune System