Animal Behavior

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					  Why do we get sick?

What things make us sick?
•Microbes that cause diseases are
called pathogens.
•They are specialized to infect body
tissues where they reproduce and
cause damage that gives rise to the
symptoms of the infection.
•The body fights back by mobilizing its
immune system to fight off the
•Modern medicine has also developed
many successful treatments to assist
the body's natural defenses.

•There are four main types of micro-

•Bacteria – single celled organisms with
no nucleus and a cell wall.
•Most are not harmful to human, in fact
we have millions of bacteria living in
our intestine and could not live without
•Bacteria are very small millions laid
end to end would not even be a meter
long. We can see a bacteria with a light
• We used bacteria to make:
  •Cheese and yogurt, they are used in
  sewage treatment plants to get rid of
  waste. Bacteria are even used to
  make human insulin!
  •But when bacteria get into places
  they should not be, it can make us
  sick or even kill us.
  •Bacteria enter the body through any
  opening. Mouth, eyes, vagina, penis.
• Diseases that bacteria can cause:
  •Food poisoning
  •Tooth decay
  •Bacterial meningitis
  •Chlamydia STD
  •Gonorrhea STD
  •Syphilis STD
What does a bacteria look like?

                    Cell wall and
                    Various shapes
What does a bacteria look like?

                    Cell wall and
                    Various shapes
            What is a fungus?

•A fungus is like a plant, it has a cell
wall but cannot photosynthesize.
•Fungus are mostly helpful used to
make food from bread, to beer.
•Fungus produce fibers that can grow
into the skin. This can cause an
           What is a fungus?

•Common diseases of fungus are
•Athletics foot
•Ringworm (various places on the skin)
•Valley Fever (internal and deadly)
          What is a protozoa?
•A protozoa is a large single celled
organism, an amoeba is a protozoa.
•Protozoa are used in helpful ways, but
can cause sickness like Amoebic
dysentery and sleeping sickness.
What is a virus?

  Is it alive?
• All viruses have two basic parts: a protein coat
 that protects the virus and an inner core made
         The Structure viruses are
 of genetic material. Someof Viruses
 surrounded by an outer membrane envelope.
•A virus is DNA or RNA coated with a
•What is DNA?
        Deoxyribonucleic Acid
•What would RNA be?
        Ribonucleic Acid
•If you remember RNA is what makes
our protein.
•A virus is DNA or RNA coated with a
•The virus enters the body and attacks
cells. Usually a viruses will attack only a
specific type of cell. Mucus cells are the
most common.
•What would a mucus cell make? Saliva
•That’s why you have a runny nose
when you get a cold!
   What does a virus look like?
Virus enter the cell and inject their
 genetic material. (DNA or RNA)

                         Protein coat
                         DNA or RNA
        Viruses are very small
10,000,000,000 viruses laid end to end
      would only be one meter
This is a virus infecting a cell.
A virus landing on a cell injecting
   it’s nucleic acid into the cell
•Once the DNA or RNA enters the cell
the virus uses organelles of the cell to
make more viral DNA (or RNA). The
virus also uses the cells organelles to
make protein for the virus cover.
•Once the cell is filled with virus, the
virus either breaks the cell membrane
and spreads to more cells or buds off
from the cell. Either way, the cell is
• Active viruses enter cells and
 immediately begin to multiply, leading
       How Virusesthe invaded cells.
 to the quick death of
   Diseases Caused by Virus
Cold Sores
Plus many, many more

Human - Only infects humans
Immunodeficiency - Causes a
 deficiency in the immune
Virus -
• Hidden viruses “hide” for a while inside
 host cells before becoming active.
      How Viruses Multiply
Human Immunodeficiency Virus
  Human Immunodeficiency Virus
•Why is this disease so deadly and
difficult to stop?
•People with HIV virus may not show
any symptoms for 10 years or longer.
•They do not know they have the
disease! They feel and look normal!
•But, infected individuals can pass the
virus to everyone they have sex with.
•How do you prevent diseases in your
body from spreading?
 White blood cells (WBC)
•WBC’s work with each other to identify
and kill pathogens (viruses, bacteria).
•A special WBC, a lymphocyte, called a
T-cell identify viruses as pathogens
and gets other WBC’s to attack and kill
•It is a very important part of your
immune system.
•Why is this disease so deadly and
difficult to stop? (continued)
•HIV attack these T-cells or helper T-
cells and destroys them.
•If the T-cells are killed the immune
system has difficulty identifying and
destroying any pathogens (disease).
  Human Immunodeficiency Virus

                       HIV Virus
Infected T-
                        How a virus
          HIV What’s Important
• Ways HIV cannot be spread!
  • Kissing any kind
  • Sharing food
  • Saliva
  • Toilet seat
  • Touching
  • Drinking fountain
  • Through the skin
• It is not easy to get!
• People with Human
  Immunodeficiency Virus can be
  tested! The virus can be identified!
• As early as two weeks after infection
  or as long as three month, antibodies
  to the virus can be found.
• For lots of (bad) reasons, people do
  not get tested.
• Why not?
       HIV What’s Important
    • How does a person with HIV
              spread it?
• Sex
• Sharing needles
• Blood
• HIV is spread through sexual contact!
   • Anal
   • Vaginal
   • Oral
HIV virus must enter the blood stream
  through an opening (cut or break) in
  the skin. There are usually openings,
  or the skin is very thin, in all three
  area above.
•HIV is spread through IV (intravenous)
drug use with shared needles.
•HIV can also be spread by needles
used to pierce the skin for jewelry
(tongue, navel, ears, lips etc.)
•HIV can be spread by contact with
infected blood.
•HIV can be spread by receiving blood
from a donor with HIV. This is usually
not the case any longer in the US. But
at one time it was! Many other
countries do not test their blood!
•You cannot get HIV by giving blood.

•Blood however in third world countries
may be contaminated.
       You can’t get HIV From:
• Normal activity with an HIV infected
  person, even deep kissing.
• You can’t get it from:
  • Insects Mosquitoes, fleas, bedbugs
  • Water (swimming)
  • Food
  • ETC.
        Best ways to avoid HIV

• Abstinence (not having sex) is the
  ONLY sure way to prevent an HIV
• Even with the use of a condom you
  still have a 10% to 15% chance of
  the condom failing.
              HIV is Silent
• People with HIV may not know it for
• They look and act normal.
• EVERYONE they have sex with can
  become infected.
• There is no cure! It is a sentence to
• What does HIV lead to?
Acquired - To get something
Immune – Ability to fight something
Deficiency – Not enough of something
Syndrome – A combination of signs
and symptoms characteristic of a
particular disease
Acquired Immunodeficiency Syndrome

    HIV only becomes AIDS When:

• The infected person becomes sick
  with another opportunistic diseases.
• They no longer look and act normal.
• They have a very low white blood cell
• Remember HIV attacks T-cells, which
  are WBC’s.
  AIDS patients die of complications
• HIV does not kill the patient the
  opportunistic disease or the drugs the
  person is taking does.
• Opportunistic disease’s strike when
  you are sick or weak.
• HIV destroys your immune system.
• Opportunistic disease can be
  pneumonia, cancer, malaria and many
•In the US we are lucky. We have the
resources to treat individual’s with
AIDS, in many other countries they
don’t. But AIDS is still a killer
•AIDS hits the poor harder than the
•AIDS infects minorities more, even in
the United States. But
           • Is It Worth It!
•In the United States
•As of June 2005 1,100,000 people
were living with HIV
•10% of the new cases of HIV show a
mutation that is drug resistant
•Through 2004 over 950,000 people
had AIDS
•Almost 600,000 people have died of
AIDS!        Is It Worth It!
AIDS diagnoses and deaths of persons with AIDS in the USA by year
                                     Cases diagnosed during the   Deaths occurring during the
                                     year                         year
             Before 1981             100                          30
             1981                    339                          130
             1982                    1,201                        466
             1983                    3,153                        1,511
             1984                    6,368                        3,526
             1985                    12,044                       6,996
             1986                    19,404                       12,183
             1987                    29,105                       16,488
             1988                    36,126                       21,244
             1989                    43,499                       28,054
             1990                    49,546                       31,836
             1991                    60,573                       37,106
             1992                    79,657                       41,849
             1993                    79,879                       45,733
             1994                    73,086                       50,657
             1995                    69,984                       51,414
             1996                    61,124                       38,074
             1997                    49,379                       21,846
             1998*                   43,225                       19,005
             1999*                   41,356                       18,491
             2000*                   39,513                       17,139
             2001*                   39,262                       17,726
             2002*                   39,250                       17,628
             2003*                                                17,283

             2004*                   38,807                       16,982
             2005*                   37,662                       16,865
             2006*                   37,852                       14,627
             Total**                 1,014,797                    565,927
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