Download “The Immune System”

What is a system?
• A group of tissues (organs) that work
together to do a certain task.
• Ex) digestive system, circulatory system,
immune system…
• Function of the immune system is to
protect your body from invasion of
pathogens.
“The War on Pathogens”
• Your body is always
surrounded by pathogens.
• Pathogen is ?.
• Viruses, bacteria, fungi, etc.
• Germ theory—infectious
diseases are caused by
microorganisms of different
types.
• Diseases can be passed from
one person to the next are
called infectious or
communicable.
Non-Specific Defense
• Your body has several defense mechanisms to
keep them out…..
FIRST LINE OF NON-SPECIFIC DEFENSE
1) skin
2) sweat
3) mucous membranes
4) saliva
SECOND LINE OF NON-SPECIFIC DEFENSE
• inflammatory response
First Line: Skin
• Physical barrier
• Chemical barriersecretes oil, sweat,
and tears
• Sheds constantly
(1 million cells per
hour)
First Line: Mucus Membranes
• These line the inside of
all body openings.
• Nostrils, mouth, lungs,
etc.
• Cells of mucus
membranes:
– secrete mucus that traps
foreign objects
– lined with hairs called
cilia.
• Stomach also has acid
Second Line of Defense:
Inflammatory Response
• The first line of defense has been broken…
• SECOND LINE OF DEFENSE ACTIVATED:
damaged cells release chemical messages that trigger
a series of reactions by body-histamine
1.) capillaries to swellpuffiness
2.) increases blood flow to infected area redness
3.) temperature in area rises
4.) pain
5.) phagocytes called inget rid of pathogens
***Sometimes this response is NOT enough…
Immune System
Non-specific Defense
Immune System
leave room to
add more here
First line:
Skin
Sweat
Mucous
Stomach acid
Second line:
Inflammatory
Response and
Phagocytes
What if pathogens circulate
through your body?
• White blood cells have to take over.
• White blood cells = “soldiers” of your immune
system.
The Immune Response
Specific Defense
• Body’s attack against
a pathogen that made
it past the “front
lines.”
• Results in “immunity”
because your immune
response creates
memory cells
SPECIFIC for each
pathogen.
• Chicken pox
SPECIFIC
IMMUNE RESPONSE
SECOND LINE OF
DEFENSE:
INFLAMMATORY RESPONSE
NON-SPECIFIC
FIRST LINE OF DEFENSE:
SKIN, MUCOUS, SWEAT
Organs of the Immune System
White blood cells
are called leukocytes
Made in the thymus
(T cells) and bone
marrow (B cells)
Stored in tonsils,
spleen, and lymph
nodes.
“The Soldiers”
White Blood Cells
• Leukocytes
–
–
–
–
–
–
Macrophages
Helper T cells
Killer T cells
B cells
Suppressor T cells
Memory cells
How does your body know
there is an invader?
• All pathogens have “distinct” marker proteins that
are antigens.
• Antigens -anything that causes an immune response.
• Your body must recognize antigens as FOREIGN
(NON-SELF) in order to create an immune
response.
Step #1 “Invader Identification”
Movie
• Macrophages identify pathogen as “non-self,” eat
it, display the antigen, and signal for helper T
cells.
• Interleukin-1 signal released= fever
• Helper T cells “signal” for the production of
other leukocytes by releasing of interleukin 2.
• The next type of leukocytes called to work are
known as B cells and Killer T cells.
Step #2 “Cloning Phase”
• Many helper T cells, B cells and killer T cells produced.
• After B cells called up by helper T’s, they begin to
produce lots of antibodies
What are antibodies?
• Millions of antibodies are
made by B cells
• They are like “keys” and
are specific to each
antigen which are like
the “locks.”
• Mark pathogen for death
and can also prevent
virus attachment to cell.
Step #3 “The Attack Phase”
• Pathogens marked with antibodies are destroyed
by macrophages.
• Killer T cells destroy any infected body cell.
Movie
Step #4 “Memory Phase”
• Macrophages act as the clean up crew,
eating pathogens, damaged body cells, etc.
• Suppressor T cells “call off the troops”.
They suppress, or weaken, the attack.
• Powerful memory T and B cells are left
behind to “remember” the attack and
quickly recognize a pathogen if it re-enters
the body.
Primary vs. secondary immune
response
– Primary:
– 1st time in contact
with pathogen.
– Takes longer for attack
– Secondary:
– come into contact with
a pathogen you’ve
already encountered
– memory B cells are
there to produce
antibodies quickly and
in greater amounts.
Primary response Secondary response
Immune System
Non-specific Defense
First line:
Skin
Sweat
Mucous
Stomach acid
Immune System
Second line:
Inflammatory
Response and
Phagocytes
B cells:
Antibodies and
Memory Cells
Specific Defense=
Immune Response
Reaction to
specific antigen
Macrophage
signal
Helper T cells
signal
Killer T cells
Active vs. Passive Immunity
• Active Immunity (immune response, vaccine)
– The body ACTIVELY produces its own
antibodies
• Passive Immunity (breast milk)
– Get antibodies from mother’s milk.
Immune System Failure
Allergies
• Allergy: Immune
system response
against a NONPATHOGENIC
antigen.
• Food, pollen, bee
stings, dust mites
Immune System Failure
Allergies
• Body produces more antibodies than you
need, which causes release of histamine:
– blood vessel dilation
– swelling
• Antihistamines are in allergy medicine that
reduce swelling.
• Asthma
• Movie
Immune System Failure
Autoimmune disease
Immune system fails to distinguish self from
non-self.
Body makes antibodies against and attacks
own cells.
Examples:
MS (attack nerve cells)
Lupus (attacks organs)
Rheumatoid arthritis
(attacks joints)
Immune System Failure
Cancer
• One major job of the immune system is
immunological surveillance.
• Killer T cells destroy our cancerous cells.
• Immune system fails to locate and remove
cancerous cell, & it multiplies to form a
tumor.
• Malignant tumor spreads, benign does not
AIDS
Acquired Immunodeficiency
Syndrome
• Sometimes the immune system collapses
totally.
• HIV (Human Immunodeficiency Virus)
invades helper T cells
• B cells and killer T cells not stimulated to
work—immune system breaks down!
• Body overwhelmed with pathogens
Immune System
Non-specific Defense
First line:
Skin
Sweat
Mucous
Stomach acid
Immune System
Second line:
Inflammatory
Response and
Phagocytes
B cells:
Antibodies and
Memory Cells
Specific Defense=
Immune Response
Reaction to
specific antigen
Macrophage
signal
Helper T cells
HIV
signal Killer T cells
Immune System Failures
Overreact:
Allergies Asthma
Can’t tell self
from non self:
Autoimmune
disease
Immune system
shut down due to
HIV:
Immunodeficiency
(AIDS)
Immunological
surveillance doesn’t
locate bad cells:
Cancer
Blood types
• Each red blood cell has protein markers
• A type blood---A protein markers
• A person with type A blood makes
antibodies against B markers because they
are foreign
• The B markers are considered antigens to
the person with A blood
Blood types
Blood types
• Universal donor: type O because no protein
markers to cause immune response.
• Universal recipient: type AB because they
have both A and B markers and so don’t
make antibodies to either.