1. The Immune System

2. Quick Definitions to Start…
Pathogen: Disease causing invaders in your body (“germs”)
Infectious Disease: Passed from other diseased organisms
Can be transmitted by…

3. Transmitting Pathogens
Method #1- DIRECT CONTACT: Shaking hands or sharing drinks
Method #2- INDIRECT CONTACT: sneezing or coughing from infected individual

4. More Methods…
Method #3- WATER/FOOD: Eating infected food (ex. E.coli bacteria in meat)
Method #4- ANIMAL BITES: Bitten by animal with disease (ex. rabies)

5. The FIRST LINE of Defense!
Skin (sweat & oil form physical barrier)
Stomach acid destroys pathogens
Mucus & cilia catch pathogens in respiratory system

6. The SECOND LINE of Defense
Innate Immune Response
Quick, general & non specific
Response is the SAME for any invader

7. Details…
Special white blood cells called phagocytes engulf and destroy pathogens!
They recognize pathogens as “foreign invaders”

8. More Details…
Fluid, cells & dissolved substances in blood rush to site of infection 
Results in 
INFLAMMATION (fever, swelling & redness at site of infection)

9. The ACQUIRED Immune Response
Very specific attack on a particular pathogen called an ANTIGEN
An antigen is a non- living particle or substance

10. We’ll label the cartoon together…
STEP 1: RECOGNITION
A foreign invader is recognized!
White blood cells signal Helper T-Cells
Helper T Cells Signal/Activate B-Cells
We’ll label the cartoon together…

11. STEP 2: MOBILIZATION B-Cells produce antibodies
Killer T-Cells can directly destroy antigens or pathogens (no antibodies required!)

12. STEP 3: DISPOSAL Antibodies destroy pathogens by binding to them
Antibodies remain in as Memory B-Cells!

13. STEP 4: IMMUNITY Memory B-Cells keep an antibody “copy”
Can be reactivated if you encounter the same antigen again!
Called ACTIVE IMMUNITY