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First Line of Defense
Skin Salivia Stomach
Acid
Sweat
Nose
Tears
Hairs
&
Mucous
First line – FAILED
A Pathogen - something
foreign to the body
Was let in.
What would be an example of
a pathogen?
Second Line of Defense
macrophages
- biggest white blood cell (W.B.C.)
-Know a pathogen by its marker proteins
- eat pathogens
-Part of the destroyed pathogen is placed on
their membrane Like a victory banner
3rd Line of
Defense
Macrophage tells
Helper T-cells the
pathogen’s
marker proteins
(remember the
Victory Banner?).
T-cells make a hormone (a message) that
tells…
-B-cells to make antibodies
-Killer T-cells to divide
B cells produce antibodies
that circulate in the blood &
lymph streams
Antibodies
Mark
pathogens
Antibodies are specific (made to mark
only a certain kind of pathogen)
Killer T-cells
- kill infected cells
- kill pathogens with antibodies
(The Killer T- cell is marked by the
arrow. It is killing a much larger
influenza virus infected target)
Suppressor T-cell
Stops the B-cells from
making antibodies.
B-cells leave behind
memory cells that
watch for the
pathogen.
If they find one, they start
multiplying to kill it.
This process is so immediate
& explosive that the
pathogen is killed before
you know you are sick.
Memory cells make you
immune to that pathogen
Second
Introduction
First
Introduction
Time
Allergies – an abnormal response to a pathogen
(pollen, dust, pets etc.)
Immune system is super-sensitive to the pathogen
and starts the first line of defense.
Viruses are made up of a protein & RNA or DNA
It is debated whether viruses are living or non-living
things since they cannot reproduce on their own.
1. Viruses inject their DNA/RNA
into our cells
2. Our cells produce the viruses
3. Our cell dies
To combat a virus we use vaccines.
Vaccines (virus) - help our body to
produce memory cells
Retro viruses (HIV) - change their protein, so our
memory cells do not recognize them.
Bacteria
are living
things
(Monera)
unlike
viruses
Good Bacteria
-make yogurt,
-treat water
- clean oil spills etc.
Antibiotics kill bacteria by
damaging their cell wall
Our cells do not have cell walls
So, antibiotics do not hurt
our cells