 What is our immune system?  A system that prevents disease and infection  The immune system “cleans the body” by removing what?  Pathogens such as bacteria and viruses

 Three things that are included in in our first line of defense include:  1. SKIN (acts as a barrier)  2. Mucus/Cilia  Mucus = sticky to trap germs  Cilia = tiny hairs that “sweep” out germs  3. Gastric Juice (acids in stomach kill germs)

 Two things that make up the 2 nd line of defense are  1. Inflammation (phagocytic WBC’s)  2. FEVER  When do we need the 2 nd line of defense?  When the 1 st line fails and pathogens get into the body!!

 1. What is Inflammation?  an increased blood flow to a part of the body that has been injured or invaded by a pathogen (hot, red, swollen)  2. Why do you think the skin over an infection is hotter than the surrounding skin?  There is more blood at that site so it raises the temperature  3. What line of defense is inflammation?  2 nd line

 What is your body’s 3 rd line of defense?  Anti-bodies  What are anti-bodies?  Specific proteins that are made by WBCs to fight off pathogens  Where would we find anti-bodies?  Plasma of the blood  What is an antigen?  Anything that can stimulate an immune response

 What is the most common shape of an anti- body?  The “Y” shape  How does the shape of an antibody change from a T to a Y?  When it connects to an antigen  Do you think antibodies are shape-specific? That is, do the antigen and anti-body have to fit together properly for it to work?  YES

 What is another name for WBCs?  Leukocytes  What does the word “phagocytosis” mean?  Cell eating

 What does it mean when we say antibodies are specific?  Their shape has to fit with the antigen they are fighting  Do you think this is a specific defense?  YES!  What happens when a pathogen invades the body?  Anti-bodies are created