Transcript The Immune System

Ch 3 – The Immune System
3.2 Factors Affecting the
Immune System
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).
Vaccines
• A vaccine is a
special version of
an antigen.
• It is a weakened
form of the
disease
• Administered by
needle usually
(liquid form)
How do vaccines work?
• A small amount of weakened disease enters
the body
• Your immune system creates antibodies to
fight the disease
• You don’t 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
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
Are vaccines risky?
• No, not generally
• Most vaccines are
accompanied by mild
side effects that
don’t last long
• Sometimes a severe
allergic reaction can
occur but this is
rare.
Extreme reaction to smallpox vaccine
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
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”.
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!
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
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.
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
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
How is HIV transmitted?
• HIV can be
transmitted through
– Blood
– Semen
• HIV cannot be
transmitted through
– Direct contact
• Shaking hands
– Saliva
• Sharing drinks, kissing
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
Keeping Your Immune System
Healthy
• What can you do?
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Eat healthy foods
Exercise
Wash your hands
Keep yourself and
your home clean
Avoid drugs/ tobacco
Get enough sleep
Get vaccinations
Be cautious (don’t
share drinks, etc..)