Transcript Pathogens and The Immune System

Pathogens and The Immune
System
What is a virus?
• Latin word for poison
• Segments of RNA or DNA
surrounded by a protein coat.
• Tiny, non-living
• Invade living things
Characteristics
of life
CELL
VIRUS
Made of cells
YES
NO
Obtain & use energy
YES
NO
Grow & develop
YES
Only inside a living
cell
Reproduce
YES
Only inside a living
cell
Respond & adapt
YES
YES
Contain RNA or DNA
YES
YES
VIRUS STRUCTURE
ENVELOPE
• Envelope (part of the
protein coat)
• Capsid – right inside
the envelope (part of
the protein coat)
• Nucleic acid (either
NUCLEIC
DNA or RNA)
ACID
Protein
markers help
virus recognize
their host
CAPSID
Retrovirus
• A virus that contains
RNA instead of DNA
• Human
ENVELOPE
Immunodeficiency
Virus (HIV) is a
retrovirus
• Genetic information RNA
is copied backwords,
from RNA to DNA
instead of DNA to
RNA.
CAPSID
Viruses: Bacteriophage
• A virus that only
infects bacteria
CAPSID
HEAD
DNA
Tail
TAIL
FIBER
Aids in
attachment
Why do scientists consider
viruses to be non-living things?
•
•
•
•
•
Do not grow
Do not eat (metabolism)
No homeostasis
Do not breath
Cannot reproduce on their
own – must infect a living
cell.
Comparison of virus and living cells
Here are 3 viruses…T4; Tobacco mosaic and
HIV…all they have is a nucleic acid core and a
protein coat
T4
Tobacco
mosaic
HIV
The two life cycles of a virus…
Once inside a cell a virus can do one
of two things…
 LYTIC cycle: enters cell, makes
copies of itself and causes the cell
to burst. Destroys host cell
 LYSOGENIC cycle: slower cycle,
virus integrates it’s DNA into the
hosts DNA. Viral DNA is
embedded in host’s DNA. host’s
body triggers the virus into action
takes a long time for the virus to
take affect (like HIV)
Viral Replication (virus
reproduction)
1. Attachment
2. Injection of genetic material into
the host
3. Making of new parts
4. Assembly of parts
5. Release of new viruses
Viral Disease in Humans
• Unlike bacterial diseases, viral
diseases can’t be treated with
antibiotics. Vaccines are used for
the prevention of some viral
diseases. Once someone has
contracted a viral disease, they
can only treat the symptoms to
make themselves feel better until
the infection clears up on its own.
Disinfectants can be used to kill
viruses on household surfaces.
SEM of a bacteriophage virus
Bacteriophage infecting a
bacteria
Lytic cycle animation
• http://biology.about.com/gi/dyna
mic/offsite.htm?site=http://facult
y.ccbcmd.edu/courses/bio141/lecg
uide/unit3/viruses/adlyt.html
A host cell in the lysogenic phase can suddenly convert to the
lytic stage…this happens with HIV…when it does, HIV
becomes AIDS.
Viral Disease in Humans
• Unlike bacterial diseases, viral
diseases can’t be treated with
antibiotics. Vaccines are used for
the prevention of some viral
diseases. Once someone has
contracted a viral disease, they
can only treat the symptoms to
make themselves feel better until
the infection clears up on its own.
Disinfectants can be used to kill
viruses on household surfaces.
Immune
System
Infectious and Non-infectious Disease
Infectious – can spread from person to
person or from one body part to
another, caused by a pathogen in
the body
Non-infectious – does not spread arthiritis
DISEASE TRANSMISSION: 5 ways to
spread an infectious disease
1. Person to person contact- STD’s,
colds, strep throat
2. Air-colds
3. Food – botulism (swollen cans)
4. Water- infected with sewage
5. Animal bites- mosquitos transmit
malaria, dogs transmit rabies
Disease Transmission
• Robert Koch established a
procedure for diagnosing causes of
infection.
• His 4 step procedure is called
Koch’s postulates.
Disease Prevention and Protection
Immunity – resistance to a
particular disease.
Vaccination – invented by Edward
Jenner. Used to produce immunity.
Vaccines contain a dead or
weakened pathogen.
Your Bodies Defenses: chapter 40
• Body uses specific and nonspecific defense
mechanisms to detect and destroy
pathogens.
1st LINE OF DEFENSE: SKIN nonspecific
(do not target certain diseases, tries to kill
anything) acts as a barrier, oil and sweat
keep many diseases from growing.
mucous membranes –line entrances
and exits of the body and trap pathogens
when they enter.
move to second line if the skin is
broken.
2nd LINE OF DEFENSE:
• 4 important nonspecific.
1. Inflammatory response –
series of events that suppress
infection and speed up recovery.
Infected cells release histamine –
causing blood (including WBC’s) to
rush to the site.
Causes swelling and redness. Pus
contains WBC’s, dead cells and dead
pathogens.
2nd LINE OF DEFENSE:
2. Temperature response – when the
body is fighting a pathogen.
Fever makes it harder for
pathogens to grow, very high
fever can be dangerous and even
kill you.
3. Proteins – circulate in the blood
and become active when they run
into certain pathogens.
2nd LINE OF DEFENSE:
4. White blood cells – patrol the
bloodstream and attack
pathogens. 3 types
1. Neutrophil – englufs and
destroys. Most abundant type.
2. Macrophage – ingest and kill
pathogens, clear dead cells and debris from
the body.
3. Natural Killer cells – large WBC
that attacks infected cells causing the cell to
swell and burst. Kill cancer cells.
• Walking macrophage"
• A major player in the
body's immune
system, this white
blood cell is probing an
airsac in a human lung
with pneumonia. It
was looking for debris,
bacteria or other
foreign matter that it
would have ingested
like a tiny vacuum
cleaner. x7000
• A large cancer cell
surrounded by natural killer
cells
3rd LINE OF DEFENSE: The Immune
Response
SPECIFIC DEFENSES
• Occurs when bodies nonspecific
defenses get overwhelmed.
• Army of individual cells that go to
war for the body attacking specific
pathogens.
3rd LINE OF DEFENSE: The Immune
Response: Cells Involved
• 4 Different types of white blood
cells –
1. Macrophages- can attack any
(not specific) consume
pathogens.
2. Cytotoxic T cells – attack and
kill
3. B Cells – remember and label
invaders and instruct
macrophages when to attack.
4. Helper T cells – activate T and
B cells.
3rd LINE OF DEFENSE: The Immune
Response: Recognizing Invaders
-The infected body cells have
ANTIGENS on their surface.
Antigens trigger the immune
response. WBC’s recognize and
respond to the antigens
-ANTIBODIES – proteins that bind to
antigens
Oh no – you have the flu- What
happens?
You just took a deep breath, the air
contained the flu virus. Here’s
what happens:
Some were trapped in mucus, but a
few slipped past.
You now have infected cells.
Macrophages begin engulfing and
destroying the infected cells.
2 Main parts of the Immune Response
1. B cell response
2. T cell response
T and B cells are produced in the
bone marrow.
Disorders of the Immune system
• AUTOIMMUNE DISEASES – immune
system cannot distinguish between
the body’s antigens and foreign
antigens. Body begins fighting
itself.
• Examples:
MS (Multiple Scelrosis)
Arthritis
Lupus
Diabetes
HIV - retrovirus
• Human immunodeficiency disorder
• HIV attacks helper T cells
weakening the immune system.
• Transmitted by body fluids.
• Most commonly transmitted
through sexual contact and
needles.
• Mosquitos and ticks CANNOT
transmit HIV.
Allergies
• Inappropriate response by the
immune system.
• Antigens bind to cells in the nose
and release histamine.
• Histamine causes redness,
swelling, runny nose, itchy eyes
and congestion.
• Take antihistamines – sudafed, etc,
to fight allergies.