Transcript Our Defense System Spring 2013

Our Defense System
Spring 2013
Two ways your body defends you
• Nonspecific – attacks invaders without
discretion. (doesn’t attack only specific
invaders)
• Specific – cells that are trained to only
attack one kind of invader (chicken pox, for
example).
Non Specific Defenses
First line of defense (4)
1. Skin
– Physical barrier as long as it’s
unbroken
– Chemical barrier – sweat
• acidic - inhibits bacterial growth
• contains lysozyme - an enzyme that
digests bacterial cell walls (also in
tears)
Non Specific Defenses
First line of defense
2.Hair –
Some are large, like
eyelashes or eyebrows
Most are very small,
called cilia, they line
the respiratory
system. They trap
and sweep particles
out
Nonspecific Defenses
First line of defense
• 3. Mucous
Membranes
– Layers of
cells that
produce
mucous.
– Trap
pathogens
Non specific Defenses
First line of defense
4. Stomach Acid
• Hydrochloric acid
(HCl)
• pH around 1 or 2
• Destroys most
pathogens you
swallow
• Stomach protects
itself with a thick
lining of mucous
Non specific Defenses
Second Line of defense (4)
1. Inflammatory
Response
2. Temperature
response
3. Proteins
4. White blood
cells
Inflammatory response – triggered
by pathogens enter the skin
• Injured cells release
histamine.
• Histamine causes local blood
vessels to dilate, increasing
blood flow in the area.
• But it also brings more white
blood cells which will
destroy the pathogens
• Increased blood flow causes
swelling, redness, raised
temperature.
Temperature Response
Normal body temperature is 37 degrees C
(98.6 degrees F)
As pathogens invade, the
body will increase
several degrees. This
will inhibit diseasecausing bacteria.
Proteins and White blood cells
• When a cell is attacked by a virus, the cell
releases a protein called interferon
• Interferon travels to other cells and prevents
the virus from successfully reproducing
• White blood cells travel throughout the body
and destroy and consume any non-self cell.
Specific Response
Certain white blood cells (T cells) are
programmed to recognize only a
particular pathogen (Called antigen)
You have thousands of different T cells.
They each recognize a different antigen.
When they recognize an antigen, they clone
themselves many times and will destroy
the antigen. Some stick around for years
and work as immunological memory
Example: Chicken Pox
• 1st grade, 1975, San Antonio, Tx. Peter
Knickerbocker (not making that name up…)
contracted chicken pox from an unknown
source.
• The virus began to attack his skin cells, but
it takes a week or so (called an incubation
period) before there was a noticeable
problem…fever, pox marks, etc.
• During that incubation period, he sat next in
the desk next to me.
Example: Chicken Pox
• I contracted Chicken pox from him and my
body had never seen it before. The first and
second line of defense went to work, but the
virus reproduced faster than the nonspecific
response could control it.
• A white blood cell consumed one of the
virus particles.
• When it consumed it, it blew a whistle by
sending out a signal (chemical: interlukin)
Example: Chicken Pox
• T cells arrive at the scene of infection. I
have thousands of them but they are all
different. One of them matches the chicken
pox virus’ protein coat.
• Before a match is found, time passes and
many more viruses replicate. I’m feeling
pretty miserable during this time…stupid
Peter Knickerbocker!!
• When a match is found, the T-cell rapidly
clones itself to make many, many, many
duplicates
Example: Chicken Pox
• The chicken pox T cell clones all destroy
the virus cells resulting in my feeling much
better
• Some chicken pox T cells will stick around
for a long time (they are still there!!). They
are called memory cells
• When I go back to school a week or so later,
Drewann Kittlitz (not making that one up
either) has gotten chicken pox (probably
from me) and spreads it back to me
Example: Chicken Pox
• My body immediately recognizes the virus
and the memory cells rapidly divide and
attack. I never even knew I had caught it
again.
• This is why you can have the flu and not
catch the flu from your own toothbrush a
week later.
• It’s all about the memory cells.
Primary and secondary response
• Let’s graph it!!
• Vaccines introduced a deadened form of a
pathogen. Your body makes the memory
cells
• Then when you are exposed to the real
thing, your body knows exactly how to fight
it.
• A vaccine is like a fire drill for your
immune system
What’s on the test
• Viruses vs. bacteria (flip chart)
• HIV/AIDS virus notes
• Pathogen chart…this portion
(Only
this portion) is open note)
• Your defense system notes