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Aim: How does our body come
under attack?
What is a disease?
Disease is any condition that prevents
the body from working as it should.
As a result the body may fail to
maintain homeostasis.
What can cause disease?
Lifestyle choices
Genetics
Toxins
Organ malfunction
Pathogens
What are pathogens?
Foreign Invaders!
Types of Pathogens
• Bacteria
• Viruses
• Fungi
• Parasites
Bacteria
• Prokaryotes
(no nucleus, missing organelles)
• Unicellular (one cell)
Examples:
• Strep throat
• Salmonella
• Syphilis (STD)
How can we treat bacterial infections?
Antibiotics are drugs used to
stop infections by bacteria.
Antibiotics will not work
against viruses!!
SuperBugs!!
Virus
• A VIRUS IS NOT A CELL (IT IS NOT ALIVE)
• Made of: DNA + a Coat around it
Viruses are GRIMEY
They can only reproduce
INSIDE a cell.
A virus works by injecting
its DNA into YOUR cells
and hijacking them
It turns your cell into a
virus producing factory…
then causes it to explode
when it’s done!
Examples
• HIV
• Chicken Pox
• Influenza (the flu)
Fungus
• Athlete’s foot
• Ring worm
What can the doctor
Prescribe?
Anti-fungal medicine
Parasites
Some animals and one-celled
organisms survive by living
and feeding on other organisms (their host).
Example: tapeworms and
heartworms
How do pathogens get in your body?
Air
Water
Contact
Blood &
bodily
fluid
Diagnosing – determine the disease
you have
Diagnosis is made based on symptoms
and an examination
Prevention vs. Treatment
Prevention – ways to avoid getting the disease.
Treatment – ways to help people with a disease to get better.
Aim: How does our body defend
us from pathogens?
Flu attack!
1st Line of Defense
•
•
•
•
•
Skin
Mucus
Hair
Tears in eyes
Acid in stomach
2nd Line of Defense
The Immune
System
• Made of proteins,
cells, and tissues that
identify and defend
the body against
foreign chemicals
and organisms
White Blood cells
• Warrior Cells!
• Defenders of the body
• Eat the bad guys to
destroy them
How does our immune system
identify pathogens?
Antigen
• A ID tag made of proteins
identifies the invader as foreign
• This ID tag is called an
antigen.
What happens after we identify the
foreign invader?
Our body makes antibodies, which
are their weapons against the foreign
antigens.
Antibodies are Y-shaped
weapons
Antibodies
Pathogen
Antibodies
Antigens
Antibodies find the
Antigens on the pathogen
& targets it for destruction !
How do antibodies destroy pathogens?
• When the antibody attaches
to the antigen, it tears open
the bad guy’s (pathogen’s)
cell membrane– and the bad
guy dies!!! 
• It also tells your immune
system cells that this guy is
ready to be eaten alive!
How are locks & keys similar to
antigens and antibodies?
Antibodies are made specifically to
match the shape of the antigen.
Antibody vs. Antigen
Antibody – weapon found in your body
Antigen – ID tag found on the pathogen
Our Immune System has a good
memory!
• Our immune system “remembers” bad pathogens it
has fought in the past
• It has weapons built up so the next time the
pathogen enters your body, you are ready to defend
yourself!
The second response
to the same pathogen
triggers a quicker and
stronger response.
** After the first response, the immune system “remembers”
specific pathogens by leaving behind cells that protect the
body for years (memory cells).
DO NOW: What is immunity?
Survivor- Tribal Immunity
Immunity: When a person is protected from
getting a certain disease.
Aim: How does your body
become immune to disease?
Farms & Better Immune systems
Types of Immunity
Vaccines
From mother
Making your own antibodies
to attack pathogens
How was the first Vaccine
developed?
English physician Edward Jenner developed
an inoculation against smallpox in 1796.
Armed with the knowledge that milkmaids
who had been exposed to cowpox, a
relatively mild affliction, didn't come down
with smallpox, Jenner intentionally infected
an eight-year-old boy with cowpox. Two
months later he infected the boy again, this
time with smallpox. As Jenner expected, the
child didn't come down with the disease -he was immune.
What is a vaccine?
Antigen
Weakened
Pathogen
Antibody
A vaccine is a dose of a pathogen destroyed so it is no
longer harmful, but it still has the antigens present.
These antigens trigger an immune response.
How do scientists make vaccines?
•
http://www.pbs.org/wgbh/nova/bioterror/v
accines.html
1) Obtain pathogen
2) Treat pathogen to
kill or weaken it.
3) Inject altered
pathogen (vaccine)
into organism.
4) Body responds to
antigens by
5)
Some
white
blood
cells
making antibodies
remain in the
& having cells
body to protect the organism
attack invader.
from future attacks.
What happens when you get
invaded by the real pathogen?
Memory
Cells are already
present and will multiply
quickly and destroy the
invader before it has the
chance to cause the
disease.
Memory
Cells
Immune response
Antibody Concentration
Real Pathogen
Interval
between
exposures
Vaccine
First
exposure
Second
exposure
Time
Bioterrorism
Today there is mounting concern
about the threat of a bioterrorist
attack using smallpox -- so much
concern that in October 2001 the
American government decided to
order enough vaccines to protect
every U.S. citizen.
Smallpox has a fearsome reputation,
having killed more people in history than
any other infectious disease.
Aim: How can the immune
system malfunction?
How can your immune system
malfunction?
1.
2.
3.
4.
Allergies
Asthma
Autoimmune Disease
Organ Transplants
What is an allergy?
• An allergy is a quick
immune system reaction
to substances that are
normally harmless
• Can you think of
materials that can cause
allergic reactions?
What are things that cause allergies?
Allergens
BEE POLLEN
RAGWEED
HOUSE DUST
MOLD
Allergic reactions
• Histamines are chemicals
that cause inflammation
• Inflammation: blood
vessels get larger to send
blood to area. You get
Itchy, warm, red.
• Hives, nausea, or shock
• What can we take for
allergies?
https://www.youtube.com/watch?v=sqrnShjM4II&spfreload
=10
Asthma is an allergic reaction
• Allergic reaction that
causes your
respiratory system to
swell up – you cant
breathe well
https://www.youtube.com/watch?v=7EDo9pUYvPE
Autoimmune disease
The immune System
mistakes your own
cells for the bad
guys, and attacks
them!
Ex: Diabetes, Multiple Sclerosis
https://www.youtube.com/watch?v=M7O78LvrNSQ
Why are organ transplants difficult?
• This is a kidney
being removed from
a donor
• The donor will have his
own ID tags on the cell
membrane. What are
these ID tags called?
Antigens!
How will the recipient react?
• A transplanted organ is recognized as foreign and is
attacked by the immune system (REJECTION).
• The chance of REJECTION is less when the donor and
recipient are closely related or when anti-rejection
medication is used.