Transcript Fighting Diseases

Fighting Diseases
Causes of Disease

many diseases are caused by
microorganisms, called pathogens
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they enter the body (called an antigen)
and either damage tissues or produce
substances that toxic to the body
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the body combats disease through the
immune system
The Immune-System Response
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the human body have many defenses
against infection
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They are categorized into THREE lines
of defense:
1.
2.
3.
External (integumentary system)
Non-specific (Innate) Immunity
Specific Immunity
1st Line of Defense
Integumentary System
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the first line of defense is an external or physical
barrier
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the human skin, if unbroken, forms an almost
impenetrable barrier against microorganisms
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cells in the nasal passages and pharynx secrete
sticky mucus that traps microorganisms and
digestive enzymes in the mucus can destroy
most microorganisms
2nd Line of Defense
Non-specific (Innate) Immunity

if invaders get pass
the 1st line of
defense and enters
the body, the 2nd
line of defense, a
complex network of
organs, works to get
rid of the infection
Lymphatic system
2nd Line of Defense
The Lymphatic System
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white blood cells (called leukocytes) seek out
and destroy invaders and are produced in the
lymph nodes
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Three types of defending leukocytes:
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Macrophages (“big eaters”, pus) – engulf antigens
Neutrophils - engulf antigens
Natural killer (NK) cells – kill invaded cells
Macrophage – “Big Eater”
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“fishing” for bacterial with long, sticky
cytoplasmic extensions
Inflammatory Response
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Histamine release – increases blood flow
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Increase capillary permeability:
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Edema – swelling, pressure on nerves = pain
Immune cells circulate better
Elevated temperature – fever, helps with
attack against pathogens
3rd Line of Defense
Specific Immunity
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Lymphocytes (another class of leukocytes)
can recognize antigens and direct an immune
response
B
lymphocytes
(B cell)
antigen
T lymphocyte
(helper T
cell)
3rd Line of Defense
Specific Immunity
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B cells – produce and display antibodies
(Plasma B cells), and some also become
memory B cells

antibodies are protein molecules that protect the
body from invaders by attaching to the surface of the
invader which makes it more easily identifiable to
macrophages

antibodies are unique to each antigen form a
response against antigens, the surface of an invader
may have many different antigens
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Helper T cells:
 release cytokines that activate more B
cells, Killer T cells, and macrophages
 Kill viruses with toxins
After the infections is over:
- B cells and T cells die, except for memory B
cells
T-Killer cells
a.k.a. cytotoxic T cells
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Match the template with the viral antigen and
kill the virus with toxins; also kill cancer cells
Active Immunity
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lasting protection against pathogens through the
production of antibodies
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can be acquired naturally, when a person
recovers from an invaders and has produced
antibodies against it OR
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artificially, by the injection of vaccines made of
dead or weaken invaders, or even isolated
antigens, the body will produce antibodies to
provide immunity towards the pathogen
Prevention of Disease Summary

Proper sterilization and/or cleaning of instruments
& surfaces
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Proper use of antiseptics (chemicals that can be
used on the skin)
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disinfectants (chemical that kill microorganisms on
surfaces) E.g., bleach
e.g. mouthwash, antibacterial soap
Proper use of antibacterial medication
Vaccinations (dead form of pathogen)
Natural human immune response
Let’s see this all in action
The Immune Response
http://highered.mcgrawhill.com/classware/ala.do?isbn=0072965819&alaid=ala_1032810&showSelf
StudyTree=true
http://www.youtube.com/watch?v=IWMJIMzsEMg
Why is it necessary to have so many different types of cells in the
immune system?
Let’s Act It Out!!!
