1. The immune system
Your bodies cavalry

2. Your defense system Made of: Skin Mucus Bone marrow
Special blood cells
Lymphoid organs
Lymph nodes
Spleen
Thymus

3. Skin Mucus 1st barrier against foreign invaders
Invaders can only get in through breaks in the skin
Natural breaks
Accidental breaks
Protects natural breaks in the skin
Sticky and traps invaders
Allows your body to safely get rid of invaders

4. Blood and bone Bone marrow Blood cells are made in the bone marrow
Immune cells called leukocytes
2 types and 3 subtypes
Lymphocytes: tags invaders
B cells
T cells
Natural Killer cells
Phagocytes: engulfs and digests invaders

5. Lymphoid organs
Lymph nodes: filters blood for invaders and stores leukocytes
Spleen: also filters blood
Thymus: stores immature leukocytes

6. Identifying enemies Skin and mucus keep everything out
The blood cells are selective
Your body must first identify invaders, learn how to kill them, then actually kill them

7. Invading the human body
It is very difficult to get into the body
1st line of defense: Skin and mucus keep stuff out
2nd line of defense: body removes irritants through coughing, sneezing, or crying
3rd line of defense: the body is very inhospitable for invaders
Strong acids in the stomach and vagina

8. If invasion is successful
If bacteria gets into the body…
Genetic markers identify foreign cells as “not you”
Something must be done!
If invaders have entered through a break or damage in the skin – inflammation response and localized fever

9. Inflammation response
Blood flow to the area is increased
This brings extra leukocytes
The phagocytes seek out foreign cells and eat them
Blood also brings platelets which block access to the body and extra nutrients which help your damaged cells repair themselves
Digested invaders are carried through the blood stream to be filtered out and released in urine

10. If invasion is successful
Fever
Body temperature will be raised where there is infection
Heat kills some types of invaders
Heat slows reproduction of other invaders
Heat can be caused by extra blood in the area