Download The Immune System

The Immune System

Protects against foreign cells and viruses
1st Line of Defense
Skin = Barrier Defense
 Mucus (respiratory tract) = traps
pathogens
 Sweat, Tears, Saliva

contains enzymes that digest cell walls
 Decrease pH of skin

2nd Line of Defense

Non specific cellular defense

Macrophages!
 Eat
cellular debris and pathogens
 Release interleukins to summon reinforcements
(helper T cells)


Achy
Fever
NOM NOM!

Inflammation
Histamine released by injured cells
 Increases permeability of capillaries (tiny
blood vessels at tissues) to allow for more
macrophages in the area
 Interferon: neighborhood warning protein
released by infected cells

3rd Line of Defense
Specific Immunity
 Cells triggered by helper T cells

T cells: destroy infected cells with “surgical
precision”
 B cells: make antibodies that paralyze viruses
 Memory cells: patrol body for rest of life

Active vs. passive immunity

Active immunity goes through all of the
steps and leads to development of
memory cells
Normal immune response
 Vaccinations


Passive immunity gives temporary
immunity via antibodies not produced by
individual
Fetus, breastfeeding
 Snake bite anti-venom

HIV

Virus that infects T cells

Disables defense system
Antibody Actions