1. KEY CONCEPT The immune system consists of organs, cells, and molecules that fight infections.

2. The immune system is the body system that fights off infection and pathogens.

3. Think of your body as a heavily guarded castle
Think of your body as a heavily guarded castle. When pathogens invade they must break down the outer wall or find a way around it. If the intruders get past the physical barriers, they must face your body’s fighters in hand-to-hand combat.
Invaders are winning= you are sick
Your body is winning= you are healthy

4. What is our first line of defense?
SKIN!!!!!!!
Cuts and wounds are entry points
What are the other entry points?
Eyes
Nose
Ears
Mouth
Excretory Organs (lungs)

5. Skin is a physical barrier to infection
It is your first line of defense!
Mucous membranes in these openings trap pathogens entering the body.
The circulatory system transports immune cells.

6. SKIN
First line of defense against pathogens
Protection from infection
Oil glands in skin
Inhibit the growth of bacteria

7. Cut yourself
Bleed
Form blood clot
Blood clot dries out- Scab is formed
Skin cells divide and multiply- (mitosis)
Scab falls off

8. Six main types of white blood cells
phagocyte- Destroys viruses, bacterium, and fungi by engulfing them
Ex: macrophage

9. 2) T cells- Destroy body cells that are infected
3) B cells- Produce proteins that inactivate pathogens that haven't infected body cells yet

10. 4) Complement Proteins: made by white blood cells, and weaken pathogen’s cell membrane allowing water in so it will burst

11. 5) Antibodies: made by B cells
Attack pathogens by “binding” themselves to the pathogen to prevent them from attacking healthy cells
Cause pathogen’s to clump, making it easier for phagocytes to engulf and destroy

12. 6) Interferons: produced by body cells infected by a virus
Stimulate uninfected body cells to produce enzymes that will prevent viruses from entering and infecting them
***If a virus can’t enter it- it can’t reproduce!