1. The Immune System Non-Specific/Innate Specific/Acquired
Always ready; immediate
• 1st line of defense: barriers
• 2nd line of defense: internal
Specific/Acquired
Response to a specific pathogen
• 3rd line of defense: antibodies
and memory cells; retained for life
The good guys
Show bad guys ppt

2. First line of Defense Barriers to Entry • Skin outer layer dead cells
oil/sweat glands
• Mucus & Cilia (hairs)
traps pathogens
induces cough, sneeze

3. • Antiseptic Body Fluids
Saliva, tears, stomach acid
contain enzymes that
breakdown pathogens

4. Second Line of Defense Once the pathogen gains entry
Macrophages - white blood cells (WBC)
ingest & kill pathogen via phagocytosis
pus is a mixture of macrophages & dead pathogens
Video

5. • Inflammatory Response Injured cells release histamines
capillaries expand (red, hot & swollen)
signals WBC to infection site
Fever
temperature increase is harmful to cells
But too hot and your cells are damaged too

6. Third Line of Defense Acquired/Specific Immunity
Tailored to each pathogen
Creates an immunological
‘memory’
aka pathogen or dust or..
Host cell or macrophage

7. Cell enzymes break down pathogen
host cell/macrophage displays bits (antigens) on cell surface
Helper T cells identify and bind to antigens
signal additional immune system cells
Pathogen enters cell
• invades host cell simple virus
• eaten by macrophage bacteria/coated virus
Response depends on pathogen type

8. Cell-mediated response intracellular pahtogens, i.e. viruses
Humoral (antibody)
Response
extracellular pathogen,
i.e. bacteria
Helper T
Killer (cytotoxic) T cells
seek, puncture memory T
& destroy cells made
B cells
plasma cell
produces memory B
antibodies cells made
Killer T lyse/destroy
infected cell
Macrophage ingests antibody-cell complex

9. Killer (cytotoxic)
T cell

10. Sources of antibodies
Non-specific
specific

11. Since it’s spring…