Our Defense System

1
Our Defense System

• Spring 2013

2
Two ways your body defends you

• Nonspecific attacks invaders without
  discretion. (doesnt attack only specific
  invaders)
• Specific cells that are trained to only attack
  one kind of invader (chicken pox, for example).

3
Non Specific DefensesFirst line of defense (4)

• Skin
• Physical barrier as long as its unbroken
• Chemical barrier sweat
• acidic - inhibits bacterial growth
• contains lysozyme - an enzyme that digests
  bacterial cell walls (also in tears)

4
Non Specific DefensesFirst line of defense

• 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

5
Nonspecific DefensesFirst line of defense

• 3. Mucous Membranes
• Layers of cells that produce mucous.
• Trap pathogens

6
Non specific DefensesFirst 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

7
Non specific DefensesSecond Line of defense (4)

1. Inflammatory Response
2. Temperature response
3. Proteins
4. White blood cells

8
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.

9
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 disease- causing bacteria.

10
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.

11
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

12
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 problemfever, pox
  marks, etc.
• During that incubation period, he sat next in the
  desk next to me.

13
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)

14
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. Im feeling pretty
  miserable during this timestupid Peter
  Knickerbocker!!
• When a match is found, the T-cell rapidly clones
  itself to make many, many, many duplicates

15
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

16
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.
• Its all about the memory cells.

17
Primary and secondary response

• Lets 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

18
Whats on the test

• Viruses vs. bacteria (flip chart)
• HIV/AIDS virus notes
• Pathogen chartthis portion (Only this portion)
  is open note)
• Your defense system notes