Chapter 40 The Immune System

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Chapter 40 The Immune System Disease

• Section 40-1
• Infectious Diseases

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Disease

• Any change, other than an injury, that disrupts
  the normal functions of the body
• Produced by
• 1. bacteria
• 2. viruses
• 3. fungi
• 4. materials in the environment
• 5. inherited traits
• Pathogens disease causing agents
• Diseases caused by pathogens are generally called
  Infectious Diseases

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Germ Theory of Disease

• Scientists Pasteur Koch concluded that
  infectious diseases were caused by microoganisms
  of different types, commonly called GERMS.
• Koch developed a series of rules still used today
  to identify microorganisms that causes a specific
  disease,
• called Kochs Postulates

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Kochs Postulates

• Turn to page 1032 copy the 4 main rules
• Identifying pathogens that cause disease is the
  first step toward preventing or curing the
  sicknesses they produce

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Agents of Disease

• The human body provides just the right condition
  for the growth of many pathogens (right temp,
  watery environment, lots of nutrients)
• Some pathogens (viruses/bacteria) destroy cells
  as they grow
• Bacteria release toxins that harm the body
• Parasitic worms removes nutrients cause body
  functions to shut down

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Viruses

• Tiny particles that invade replicate within
  living cells
• Attach to cell, insert DNA/RNA into nucleus and
  take over the cells functions
• Can infect every type of organism
• Colds, flu, smallpox, chicken pox, herpes, HIV
• No cure

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Bacteria

• Most are harmless to humans
• Few are deadly
• Cause disease 2 ways
• 1. break down tissue in infected organism
  for food
• 2. release toxins that harm body
• Ear infections, strep throat, anthrax

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Protists

• Small parasites that live on insects, animals,
  plants and contaminated water
• Cause the single most damaging infectious disease
  MALARIA

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Worms

• Flatworms roundworms are responsible for many
  human diseases
• Usually are found in contaminated water or living
  on other organisms
• Tapeworm, ringworm hookworms are examples

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Fungi

• Most are harmless to human
• Athletes Foot cause by Tinea, that penetrates
  the outer layers of the skin
• Can infect the nails, mouth throat

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How Diseases are Spread

• From 1 person to another through coughing, or
  PHYSICAL CONTACT
• Through contaminated water or food
• Spread through infected animals

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Direct Physical Contact

• Through touching a person who is infected
• Through sexual contact this includes kissing
  !!!!

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Indirect Physical Contact

• Carried through the air coughs sneezes
• Touching an object that has pathogens on it
• Can be prevented
• 1. cover mouth when coughing/sneezing
• 2. washing hands

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Contaminated Food Water

• Food poisoning is caused by eating food that
  contains pathogens
• Bacteria is always present in uncooked meat
• Bacteria grow rapidly in warm, partially cooked
  food
• Contaminated water causes disease, especially in
  areas with poor sanitation untreated sewage

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Infected Animals

• Animals also spread disease
• Animals that carry pathogens from person to
  person are called VECTORS
• Malaria, Lyme disease, West Nile Virus, rabies
  are diseases carried by vectors

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Fighting Infectious Diseases

• Prevention isnt always possible
• Some medicines have been developed to fight
  pathogens
• Antibiotics compounds that kill bacteria
  without harming the cells of the organism
• Antibiotics have no effect on viruses, only
  bacteria
• Antiviral medicines stop the ability of viruses
  to invade the cells

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Over the Counter Medicines

• Treat only the symptoms of the disease
• Help you feel better but does not treat the
  cause of the infection
• Best treatment rest, well-balanced diet,
  plenty of fluids

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Section 40-2 Immune System

• A series of defenses that guard your body against
  disease
• Recognizes, attacks, destroys, remembers each
  type of pathogen that enters the body
• Produces specialized cells that inactivate the
  pathogen
• Function to fight infection by producing cells
  that inactivate foreign substances or cells
• This is called IMMUNITY

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Nonspecific Defenses

• The fortress walls around the body
• Do not discriminate between 1 threat and another
  (reacts the same no matter what)
• Include physical chemical barriers
• 1st Line of Defense
• 1. Most important SKIN
• 2. mucus, saliva, tears, oil sweat glands
• 2nd Line of Defense inflammatory response

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Skin

• Very few pathogens can get across the layers of
  dead cells on the surface
• When broken (cuts or wounds), pathogens enter
  very easily multiply
• Causes symptoms of INFECTION
• 1. swelling
• 2. redness
• 3. pain
• 4. heat

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Secretions of the Body

• Mucus, saliva and tears - all contain LYSOZYME
  breaks down the cell walls of bacteria
• Oil sweat glands produce an acidic environment
  on the skin that kills many bacteria
• Mucus in mouth nose help trap pathogens
• Stomach acids digestive enzymes destroy many
  pathogens that get in your stomach

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Inflammatory Response

• A nonspecific defense reaction to tissue damage
  caused by injury or infection
• Millions of white blood cells are produced
  which fight the infection
• Blood vessels near the wound expand, allowing the
  WBCs to travel faster to infected tissue
• WBCs engulf destroy bacteria
• Area becomes swollen painful
• Body release chemicals to increase body temp.
  fever slows or stops the growth of the pathogen
• Fever also causes heart rate to increase which
  pushes WBCs to infected tissue faster

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Interferons

• Proteins that help other cells resist viral
  infections
• Interfere with the growth of the virus
• Slows down the progress of the infection gives
  the immune system time to respond

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Specific Defenses

• If a pathogen gets through the nonspecific
  defenses, the body STARTS the IMMUNE RESPONSE
• ANTIGENS substances that trigger this response
  viruses, bacteria
• Cells in the immune system can recognize these
  antigens are called - lymphocytes

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Lymphoctyes

• B Cells provide immunity against antigens
  pathogens in body fluids
• - this is called HUMORAL IMMUNITY
• T-cells provide defense against abnormal cells
  pathogens inside living cells.
• - this is called CELL-MEDIATED IMMUNITY

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Humoral Immunity

• When a pathogen enters the body, it is recognized
  by a small amount of B cells
• These B cells grow divide rapidly producing
  many memory B cells Plasma cells

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Plasma cells

• Plasma cells release ANTIBODIES recognize
  bind to antigens
• Antibodies attack the pathogen until it has taken
  it over
• Once infection is gone, the plasma cells die
  stop producing antibodies

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Memory B Cells

• Remember every pathogen that enters the body
• Able to produce antibodies if exposed again
• Greatly reduces the chance of being infected
  again

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Antibody Structure

• Shaped like a Y and has 2 binding sites to
  connect with antigens
• The different shapes give antibodies the ability
  to recognize a large variety of antigens
• Its estimated that a healthy adult can produce
  about 100 million different types of antibodies

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Cell-Mediated Immunity

• The bodys primary defense against its own cells
  when they have become cancerous or infected by
  viruses
• Also important in fighting infection by fungi
  protists
• Viruses other pathogens can not be destroyed by
  antibodies alone

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Process of cell mediated immunity

1. T cells divide change into Killer T cells,
   Helper T cells, Memory T cells
2. Killer T cells find destroy the pathogen or
   foreign tissue that contains the antigen
3. Helper T cells produce Memory T cells
4. Memory T cells remember the antigen in case of
   future invasion
5. Once pathogen is taken over, Suppressor T cells
   shut down Killer T cells

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Acquired Immunity

• when immunity is taken from outside the body
  not naturally made
• Two types
• Active Immunity
• Passive Immunity

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Active Immunity

• Vaccination injection of a weakened form of a
  pathogen to produce immunity
• More than 20 serious human diseases can be
  prevented by vaccinations
• Modern vaccines stimulate the immune system to
  create millions of plasma cells ready to produce
  specific types of antibodies
• When the body reacts to the vaccines it is known
  as Active Immunity

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Passive Immunity

• When antibodies produced by other animals against
  a pathogen are injected into the bloodstream
• Last only a short time
• Can develop naturally - passing from mother to
  child through placenta or breast feeing
• or by deliberate exposure - vaccines for malaria
  or when someone is bitten from snake or rodent