The Immune System

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

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

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)

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

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

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

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

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

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…

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

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

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