Your body system

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Your body systems defense system in Action
Immune System

• On guard

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First line of defense

• The skin serves as a physical barrier to prevent
  the passage of many disease-causing
  microorganisms. The skin is also slightly acidic
  and has good bacteria.

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Antigens

• Antigens are substances that cause the immune
  system to attack. An example of an antigen is a
  surface protein of a flu virus. Cells produce
  antibodies to fight antigens. Antibodies destroy
  pathogens directly or signal immune cells that
  pathogens are present.,

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Specific mechanisms of host resistance

• This specific immune response enables the body to
  target particular pathogens and pathogen-infected
  cells for destruction. It depends on specialized
  white blood cells called lymphocytes produced in
  the bone marrow .
• T-cells (produced from lymphocytes that matured
  in the thymus gland)
• B-cells (produced from lymphocytes that matured
  in the bone marrow).

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Production and Maturation

• All lymphocytes, macrophages and red blood cells
  produced in bone marrow and T cells mature in
  Thymus and B cells stay in bone marrow to mature

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T-helper

• These cells travel through the blood and lymph,
  looking for antigens markers on foreign cells.
  Upon locating an antigen, they notify other cells
  to assist in combating the invader.
• T-helper cells do this through the use of
  cytokines (or specifically, lymphokines) which
  help destroy target cells T-killer cells,
  activate B cells and stimulate the production of
  healthy new tissue. Interferon is an example of
  such a cytokine one treatment of HIV which
  infects and kills T-helper cells.

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B-cells get turned on by T-helper cells to make
specific antibodies that tell macrophage to get
them out of the way

• T-killer cells get help from T-helper cells to
  turn on then do the killing

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Vaccines

• Vaccinations give the body a preview of dangerous
  antigens.
• This allows the body to develop antibodies to
  fight this antigen.
• The body is able to generate an immune response
  quickly to prevent the disease from doing harm to
  the body.
• Brain Pop Video

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Common pathogens

• Pathogens cause disease.
• Bacteria and viral pathogens are the most common
  causes of human disease.
• Other pathogens protists, parasitic worms or
  helminths , and fungi

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Bacteria

• Bacteria can also cause infections.
• When bacteria enters a host they are able to
  reproduce in large numbers and may produce toxins
  that affect the health of the host.
• The bacteria and their toxins are perceived as
  antigens by the body.
• Antibiotics can be an effective treatment for
  bacterial infections.

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Viruses

• Viruses lack ribosomes and are not able to
  reproduce on their own. Viruses infect cells and
  use the cellular components to reproduce and
  spread to other cells.

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Virus Infection
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Viruses

• When necessary viruses are treated with
  anti-viral medications that prevent their
  reproduction within the host. Antibiotics are
  not effective against viruses.
• Examples of viruses
• Influenza (flu)
• Herpes
• HIV

Influenza Virus
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HIV-AIDS

• HIV attacks key cells involved
  in the bodies immune system_____________.
• Infected individuals can not recognize antigens
  or are not able to mount a response.
• These individuals can then be killed by
  harmless diseases because their immune system
  does not respond.