Transcript Non-Specific Defense

Let’s get DEFENSIVE
Triggering a response
Antigen:
• Any substance capable of triggering an immune
response.
• Can be a bacterium or a virus.
• Can be tissues or cells from another individual
Pathogen:
• Any disease causing agent
Lymphatic system
• A network of
glands and vessels
that drain
interstitial fluid from
body tissues and
return it to the
circulatory system.
• Fluid is “scanned” for
foreign cells
Lymph organs
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bone marrow
lymph nodes
spleen
thymus
Function of 2 Main Groups of Cells
1. Leukocytes—Non-specific defense. Rely on
Phagocytosis to ingest invading microbes.
They include Macrophages and White Blood
Cells.
2. Lymphocytes—Provide high specificity and
diversity to the immune system. Allow for
extremely aggressive response to a microbial
attack. They include B-Cells and T-Cells
Problem
Foreign cells like bacteria enter the body and
consume our cells and damage tissue.
Foreign cells give off toxins, chemical by
products of their metabolism, that are
poisonous to many of our cells (enzymes)
How to identify and destroy only the
foreign cells and not attack our
own?
Three Level Approach to Problem
Level I - Non-Specific Defense:
Prevent entry
• Skin
• Mucous Membrane
• Secretions of skin and mucous
membranes
Level 2 – Non-Specific Defense:
Search/Destroy at point of attack
foreign objects
• White blood cells
• Antimicrobial proteins
• Inflammatory response
 Damaged cells
release chem.
Signals:
 histamines
 protoglandins
Capillaries dilate
 More permeability
 Clotting elements
(Platelets) appear
 Clotting begin
 Phagocytic
leukocytes
enter region
 Attracted to
chem. sig.
 Leukocytes
consume
pathogens and
cell debris by
phagocytosis
Level 3 - Specific Defense:
Complex system of interacting cells
(immune pathway)
Pathogen  Macrophage  T- Cell 
B-Cell  Antibodies
Macrophages identify germs
When a germ invades our bodies, macrophages gobble up
the germ and display its surface shape, or antigen, for other
immune cells to see.
Helper T cells direct the defense
Helper T cells spot the foreign antigen on the macrophage
and begin to multiply. They alert other white blood cells and
direct the body's defense.
B cells make antibodies
B cells start to make chemicals called antibodies. Antibodies
lock onto foreign antigens making it easier for other immune
cells to destroy them.
Killer T cells destroy germs
Alerted by helper T cells, killer T cells multiply and destroy
the invading germs. Working together, our white blood
cells can usually destroy invading germs.
Antibody
An antibody is a
protein used by the
immune system to
identify and
neutralize foreign
objects like
bacteria and
viruses.
Each antibody
recognizes a
specific antigen
unique to its target.
Vaccines
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Inactivated bacteria or virus
Provokes immune response but not the
disease or illness
Memory cells react faster to second
exposure
Some pathogens mutate too quickly to
be eliminated by vaccines
Viruses
a. Basic Structure:
• Contains genetic information.
• Surrounded by a protein coat.
• They may have external structures and a
membrane.
• NOT Living
b. Virus Diagram
c. Examples of Viruses
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Hepatitis B
HIV
Measles
Mumps
Rabies
Ebola
Influenza
Do not draw
Retroviruses (backwards)
Instead of DNA, Retroviruses infect cells with
RNA.
– The RNA is then copied into DNA by an
enzyme called Reverse Transcriptase inserted
as a prophage like the Lysogenic cycle.
– HIV is one example of a retrovirus
Can mutate very easily and become resistant to
treatment – the problem w/ HIV
Viruses are not always bad!
• Today, in genetic research viruses are
commonly used.
– The viral genetic info can be removed and
replaced with new genetic information.
– These modified viruses can then be inserted
into other organisms, allowing the virus to
inject its new (good) genetic info into the host
cell.
• Called a Vector
Bacteria (prokaryote)
a. Basic Structure
• Lacks membrane
bound organelles
• Except they do
have small
ribosomes!
b. Diagram
DNA is typically circular,
not in chromosome form
Identifying Bacteria
 Gram Staining – stain affects bacteria
differently based on their cell wall structure
 Gram positive = purple
 Gram Negative = pink
 Shape – 3 different shapes are common
 Cocci - Sphere shape
 Bacilli - Rod shape
 Spirilla - Spiral shape
Viruses vs. Bacteria
Antibiotics work on bacteria NOT on viruses