Download Immune System

Immune System
The body’s defense system
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
Lymphatic system (Protection 3)
Lymph nodes, spleen, tonsils, thymus gland, appendix
Lymph node – contains lymphocytes
(T-cells, B-cells)
Type of white blood cell
-Filters pathogens
that defends the body
-Armpits,neck, intestines….
-get big when infection present
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.
Antibody Immunity
• Antigen – the foreign invader surface proteins
(recognized phagocytes/lymphocytes)
– When an antigen is present, body produces
___________
antibodies in response, that are specific
(complementary) to that antigen (shape
matches!)
Check out the cartoon
http://www.nyscience.org/whataboutaids/whatis/immune/content.html
What? I don’t understand!
• Macrophage eats pathogen (puts antigen on surface)
• Proteins from antigen are expressed on macrophage
surface
• T-cells recognize these antigen proteins as non-self and
start signaling
• Some become Killer T-cells – secrete enzymes directly
into infected cells and kill them
• Others become Helper T-cells which stimulates more
Killer T-cell growth, and stimulates growth of B-cells
and their production of antibodies (helper T-cells are
like the conductor of an orchestra – telling everyone
when and how to play)
Vaccines (Active immunity)– viral protein without genetic
Info. (either from outside of envelope
or the capsid protein itself)
Prepares immune system for future
Attacks, gives time to build up defense
(helps Acquired Immunity)
Vaccines
•
•
•
•
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
Antibiotics
• Chemicals produced by other organisms (like other
bacteria or fungi) that kill/inhibit bacterial growth (not
viruses!)
• Eg. Penicillin, Ampicillin….
• Harms/prevents formation of bacterial cell wall (makes
holes) – causes water to flow in [from high to low
concentration, remember?] and kills bacterium.