Ch 3

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Ch 3 The Immune System

• 3.2 Factors Affecting the Immune System

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Immunity

• Recall if our bodies contain the antibodies for
  specific antigens, we have what is called
  immunity.
• We develop immunity when we get sick and our body
  makes antibodies to fight an antigen.
• We can also obtain immunity by receiving a
  vaccine (vaccination).

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Vaccines

• A vaccine is a special version of an antigen.
• It is a weakened form of the disease
• Administered by needle usually (liquid form)

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How do vaccines work?

• A small amount of weakened disease enters the
  body
• Your immune system creates antibodies to fight
  the disease
• You dont become ill because there is such a
  small amount of weakened disease
• But some antibodies remain
• They can be reactivated if the antigen enters
  your body in the future

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More about vaccines

• Vaccines can be a one-shot deal or you may get
  another vaccination every few years.
• For example, we get tetanus shots every 10 years
  to bolster antibody production.
• Some vaccines you receive as a baby

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Are vaccines risky?

• No, not generally
• Most vaccines are accompanied by mild side
  effects that dont last long
• Sometimes a severe allergic reaction can occur
  but this is rare.

Extreme reaction to smallpox vaccine
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Disorders of the Immune System

• Some people have an unusually high sensitivity to
  a certain substance.
• When the substance enters their body, the immune
  system recognizes it as an invader and the system
  over-reacts!
• This sensitivity is called an allergy

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Allergies

• There are many things that can cause allergies.
• Food (milk, gluten, peanuts, strawberries)
• Pollen, dust
• Cats, beestings
• Any substance that causes an allergic reaction is
  called an allergen.

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Did You Know?

• Dust allergies may actually be due to the feces
  of dust mites that live in house dust!
• Dust mites eat dead skin flakes and make their
  home in your bed, carpet and old clothing!

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Allergy Symptoms

• Common symptoms of an allergy
• Runny nose
• Watery eyes
• Why does this happen?
• When your body needs to fight an invader (an
  allergen) it releases a chemical called histamine
• Runny noses and watering eyes are side-effects of
  histamine
• We use drugs called anti-histamines to reduce
  these symptoms

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Severe Allergic Reactions

• Some people have more severe allergies
• Ex peanuts, bee-stings
• If they come in contact with these allergens they
  can have a severe reaction called anaphylactic
  shock
• Results in swelling, difficulty breathing, can be
  fatal
• People often carry adrenaline-shots (EpiPen) to
  reduce the effects.

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Disorders of the Immune System

• AIDS
• Acquired Immunodeficiency Syndrome
• Infection of the immune system that can lead to
  death
• Caused by a virus called human immunodeficiency
  virus (HIV)
• HIV is a fierce pathogen that attacks the immune
  system and destroys it

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What does HIV do to the body?

• HIV infects helper T cells
• Since helper T cells activate B cells, your body
  can no longer activate B cells or killer T cells
• The immune system has no way to fight the
  pathogen
• In other words, the immune system shuts down
• Other antigens or pathogens can enter and your
  body has no way to fight against them

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How is HIV transmitted?

• HIV can be transmitted through
• Blood
• Semen
• HIV cannot be transmitted through
• Direct contact
• Shaking hands
• Saliva
• Sharing drinks, kissing

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Cure for AIDS?

• There is currently no known cure for AIDS
• HIV keeps changing its structure slightly
• There are also several forms of the virus
• A person infected with HIV live 4-10 years
• AIDS currently affects more than 40 million
  people

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Keeping Your Immune System Healthy

• What can you do?
• Eat healthy foods
• Exercise
• Wash your hands
• Keep yourself and your home clean
• Avoid drugs/ tobacco
• Get enough sleep
• Get vaccinations
• Be cautious (dont share drinks, etc..)