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Immune System
Disease
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A disease is any change other than
injury, that disrupts the normal
functions of the body. Some diseases
are inherited, others are caused by
materials in the environment.
Still others are caused by agents such
as bacteria, viruses, fungi, animals
such as worms, etc..
Pathogens
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Disease-causing agents such as
bacteria are called pathogens.
(sickness makers)
Diseases caused by pathogens are
called infectious diseases, because the
agents that cause infect the body they
enter.
Toxins
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Toxins are poisons that produce illness
by disrupting bodily functions.
Some bacteria cause disease by
producing toxins and injecting them
into host cells.
Animals that carry disease-causing
organisms from person to person are
called vectors.
Antibiotics
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Antibiotics are compounds that kill
bacteria without harming the cells of
humans or animals.
Antibiotics work by interfering with the
cellular processes of microorganisms.
They have no affect on viruses
Penicillin was discovered in 1928 by
Alexander Fleming.
http://www.biography.com/people/ale
xander-fleming-9296894
Vaccines
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Killed or weakened viruses.
The injection of a weakened or mild
form of a pathogen to produce
immunity is known as a vaccination.
Today more than 20 serious human
diseases can be prevented by
vaccinations.
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https://www.youtube.com/watch?v=y
0opgc1WoS4
https://www.youtube.com/watch?v=3
aNhzLUL2ys
First Line of Defense
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The body has several physical barriers:
An outer layer of intact skin
 Hair in the nostrils
 Mucous membranes
 Cilia
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Mucus in your nose or throat traps viruses
and bacteria
Stomach acids and digestive enzymes
destroy many pathogens.
Mucus, saliva, sweat, tears contain an
enzyme that breaks down the cell walls of
many bacteria.
Cilia
Second Line of Defense
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The inflammatory response is a
defense reaction to tissue damage
caused by injury or infection.
White blood cells leak from the vessels
to enter the infected tissues. They
engulf and destroy bacteria.
The infected tissue may become
swollen and painful.
The Immune Response
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If a pathogen is able to get past the
body’s first few lines of defense the
immune system reacts with a series of
specific defenses that attack diseasecausing agents.
A substance that triggers this response
is called an antigen.
White Blood Cells
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Leukocytes (White blood cells)
 Macrophages
 Lymphocyte (B cells, T cells, &
cytotoxic)
 Basophil (release of histamine and
inflammatory response)
Video Clip
Third Line of Defense
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Antibodies
– Antigens
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Are foreign substances that cause an
immune response.
– Antibodies
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Are proteins found in blood plasma that
attach to one particular kind of antigen and
help counter its effects.
Lock and Key
what does that remind you of?
Video Clip
Permanent Immunity
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Once the body has been exposed to a
pathogen, millions of memory B and T
cells remain capable of producing
specific antibodies to that pathogen.
Immune System
Disorders
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Video
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Allergies result when antigens from
allergens (pollen, dust ball, dust mites) bind
to a type of immune cells. The immune cell
becomes activated and produces a chemical
called histamine.
Histamines increase the flow of blood and
fluids to the surrounding area. They
produce the sneezing, runny eyes and nose.
Antihistamines are drugs that are used to
counteract the effects of histamines.
Autoimmune Disease
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When the immune system makes a
mistake and attacks the body’s own
cells, it produces an autoimmune
disease.
A.I.D.S.
– HIV, the AIDS virus
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Attacks helper T cells
– HIV has one of the fastest rates of
mutation of any pathogen ever studied.
– Drug-resistant HIV strains are now being
documented in newly infected patients.
– Exhibits how this virus readily adapts through
natural selection.