Download The Immune System

The Immune System
• Before the 1900’s, no one knew what caused
sickness and infection
• Most people thought evil spirits, swamp gas,
or bad luck caused disease
science history
Louis Pasteur
Theorized that
microbes caused
disease and killing
them could prevent
illness.
Joseph Lister
Robert Koch
Theorized that
microbes caused
infection. One of the
first surgeons to
disinfect
instruments.
Began linking certain
pathogens to certain
illnesses. Example:
botulinum causes
food poisoning.
Functions
• To keep out or to fight pathogens that enter
your body.
• To recognize and attack foreign substances in
the body.
organs
• skin
• white blood cells
– macrophage
– T cell
– B cell
• pathogen – something that causes illness.
Pathogens can be a virus, bacteria, protein,
fungi or protist.
protein
virus
bacteria
fungi
protist
external defenses
• Your body’s first line of defense against
pathogens is to create a barrier.
– skin
– breathing passages
– mouth
– stomach
skin
• Your skin acts as a barrier to keep pathogens
out.
breathing passages
• Small hairs in your nose and trachea help
trap pathogens.
• They can cause you to sneeze or cough to try
and expel the pathogens.
mouth and stomach
• Saliva and stomach acid can kill some
pathogens.
• Vomiting can also expel pathogens.
internal defenses
• If a pathogen makes it past the external
defenses, the internal defenses begin;
– Inflammation – happens with cuts and injuries
– Fever – body raises your temperature to try and
kill the pathogens.
– Immune response – white blood cells are
produced.
Immune response
• white blood cells – cells that travel though
the bloodstream and body searching out
pathogens. The three types are macrophages,
T cells and B cells.
macrophages
• Destroys pathogens by engulfing and digesting them.
T Cells
• Helper T cells travel
throughout the body
looking for pathogens.
• Killer T cells attack
certain pathogens.
B Cells
• B cells produce
chemicals (antibody)
that destroy
pathogens.
• Antibodies fight
disease.
the immune response
• A pathogen enters the body
–A macrophage finds it, engulfs and
destroys it.
–A helper T cell finds it
• activates a killer T cell destroys the
pathogen
• finds a B cell to release antibodies
to destroy the pathogen
building immunity
• The body builds immunity against a disease
when it is exposed to pathogens.
• immunity – the ability to resist or recover
from an infectious disease. You are born with
some immunities, develop some from being
exposed to pathogens and can be vaccinated
for others.
building immunity
• Your body has billions of T and B cells but it
doesn’t produce very many for each
pathogen.
• Once you are exposed to a certain pathogen,
like chicken pox, your T and B cells produce
memory cells.
• The next time you are exposed to that
pathogen, the memory cells trigger the
production of a large number of T and B cells
for that pathogen.
vaccination
• vaccine – a substance prepared from killed or
weakened pathogens that is introduced into
the body to provide immunity.
• The vaccine triggers the body to make
memory cells.
Edward Jenner was
the first scientist to
create a vaccine. It
was for small pox.
challenges to the immune system
• A healthy immune system is very good at
keeping us from being sick.
• However, we are exposed to challenges to
out immune systems all the time.
– allergies
– cancer
– immune deficiency
– auto-immune disease
• allergy - disorder in which the immune system
is overly sensitive to a foreign substance.
• pollen
• dust
• mold
• food
• medicine
• animals
• cancer - disease in which cells multiply
uncontrollably, destroying healthy tissue.
• Can exist in a tumor or can spread in the blood.
• Cause:
• genetics
• chemicals
• immune deficiency – some disease cause
the immune system to become weak.
• The most common for humans is HIV
which is the virus that causes AIDS. It
causes the immune system to fail.
HIV Virus
The virus that causes
aids
The virus gets into T
cells and reproduces
inside of them
As the T cells die, the
body loses it’s ability to
fight disease
• auto-immune disease – a disease in which
the immune system attacks itself.
• Rheumatoid arthritis is one example.
Preventing Infectious Disease
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Don’t share items that touch your mouth
Wash hands frequently
Cover mouth when sneezing or coughing
Get 8 hours of sleep
Eat a well-balanced diet
Regular exercise