Important system that helps fight off pathogens

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Immune System

• Important system that helps fight off pathogens
• What is a Pathogen?
• Microorganism that causes infection or a
  disease
• Bacteria Viruses Fungi
  Protists/Parasites
• Made of many cells each with a specific job
  including
• a. Lymphocytes
• White blood cells or WBC
• Target specific Pathogens

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Types of Lymphocytes

• T cells -
• Identify Pathogens by recognizing
• their Antigens
• B cells -
• Produce chemicals called Antibodies
• Macrophages
• Surround pathogen and digest or eat it
• Also called Phagocytes

Pathogens
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Types of Lymphocytes

• What are the Two Types of T Cells?
• 1. Natural Killers Cells
• 2. Cytotoxic Cells
• Destroy pathogens after they are marked by
  antibodies
• Destroy cells that are infected with a virus
• Also recognize cancer cells and destroy them
• What are Memory Cells ?
• Remember what type of antigens a pathogen has
• Help immune system recognize the pathogen if
  it invades our body again!! AMAZING ! ! !

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ANTIGENS AND ANTIBODIES

• What are Antigens?
• Special proteins on surface of cells and
  pathogens
• They are recognized by the Immune System
• Why?
• So that the White blood cells know which
• pathogens they need to destroy!!!
• What are Antibodies?
• Special proteins that recognize specific
  Antigens on Pathogens
• Mark the pathogens for destruction by WBCs

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Pathogens

• What are Pathogens?
• Organisms that cause disease
• Infectious diseases are?
• Diseases that are caused by pathogens .
• When you have an infectious disease pathogens are
  inside your body causing harm

• Staphyloccocus aureus
• Magnified 20,000X
• About 1 um in size
• What type of pathogen is Staph?
• BACTERIA

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4 TYPES OF COMMON PATHOGENS

• Can you guess what they are?
• Viruses Fungi Bacteria
  Protists/Parasites
• 1. Viruses
• Flu HIV Measles
  Virus
• 2. Fungi
• Athletes Foot
• Candida albicans
  Fungus

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4 TYPES OF COMMON PATHOGENS

• 3. Bacteria
• STAPH
  Bacteria
• Strep throat
• 4. Protists
• Paramecium
  Giardia
• Giardia

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The Immune System
together to The immune system includes T cells
and B cells. The cells work fight infections.

• The immune system includes T cells and B cells.
• The cells work together to fight infections.
• How does the immune system work? Lets find out!!

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T-Cells have more than one jobOne job may be
toWhat happens when a virus infects a cell?
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What is another job of the T- cells?
.
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So, why do Bcells produce antibodies?Because
..
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ImmunityHow does
a person become immunized?How does a person
become immunized? .
ImmunityHow does a person become immunized?
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How does the Immune System work
How does the Immune System work
T cells recognize bacterial or viral antigen.
Some T cells attack cells infected with pathogens.
Other T cells signal B cells to produce
antibodies .
Antibodies attach to the antigens on
virus or bacteria
(Lock Key)
Antibodies help phagocytes destroy the bacteria
or virus
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Two Types of Immunity

• Active Immunity
• Immune system produces antibodies
• on its own in response to a pathogen
• Passive Immunity
• Antibodies are injected into a patient to
• help prevent a disease from a pathogen
• Vaccine
• Contain a weakened pathogen that stimulates
  production of antibodies without causing the
  actual disease, or
• Antibodies are already in the vaccine

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Active Immunity Both Passive Immunity

The body makes antibodies.
Antibodies are given the body does not make
antibodies.
Can prevent diseases
Memory cells recognize antigens from the pathogen.
Immunity can be acquired from the mother during
pregnancy.
May involve an injection
Immunity may last for years or a lifetime.
Immunity lasts only a few months.
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Review Questions

• 1. Question What is the function of the immune
  system?
• Answer Helps fight off pathogens.
• 2. Question Which 3 white blood cells or
  lymphocytes help destroy
  pathogens?
• Answer Macrophages, B cells and T cells
• 3. Question What is an antigen?
• Answer Special protein on surface of
  pathogens recognized by the
• immune system

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Review Questions

• 4. Question What is an antibody?
• Answer Special protein in the immune
  system that recognizes and attaches to
  a specific antigen on a pathogen
  and marks it for destruction.
• 5. Question Explain the difference between
  Active and Passive Immunity?
• Answer In Active immunity the immune
  system produces the antibodies.
• In Passive immunity the
  antibodies
• are injected into a patient
  to destroy the pathogens

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Review Questions

• 6. Question Which cells of the immune
  system produce antibodies?
• Answer B cells
• 7. Question Which cells produce B cells?
• Answer T cells
• 8. Question What are the 3 important jobs of
  T-cells?
• Answer
• a. Destroy pathogens after they are marked
  by
• antibodies
• b. Destroy cells that are infected with a
  virus
• c. Also recognize cancer cells and destroy
  them

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• 9. Questions What are the 3 main functions of
  T-cells
• Answer
• Destroy pathogens after they are marked by
  antibodies
• Destroy cells that are infected with a virus
• Also recognize cancer cells and destroy them
• 10. Question What are the 4 common pathogens?
• Answer Virus Bacteria Fungi
  Protists/parasites
• 11. Question Why cant scientists produce an
  effective vaccine against HIV?
  
• Answer Because the virus mutates and the
• vaccine no longer works