1. THE IMMUNE SYSTEM What happens when we get sick? Why do we get better?

2. K-W-L: How does your body fight infection? What do you Know? What do you Want to know? What have you Learned?

3. What are some of the substances or invaders that are targeted by the immune system? Turn to your neighbor and share your thoughts

4. Foreign Invaders Any non-self substance capable of triggering an immune response is known as an antigen. An antigen can be a whole non-self cell, a bacterium, or a virus.

5. How does your body know when a substance is an invader?

6. ANATOMY OF THE IMMUNE SYSTEM The immune system is localized in several parts of the body –immune cells develop in the bone marrow and thymus –immune responses occur in the secondary organs

8. There are three lines of defense against infection

9. First Line of Defense: The outer layer of the body Primary goal: prevent organisms from gaining access

10. Second line of defense: Cells and proteins in our blood stream Primary goal: recognize, neutralize and destroy invaders

11. Third Line of Defense: The Immune Response Two types of cells are involved: –B cells: provide immunity against antigens and pathogens in the body fluids This is called humoral immunity –T cells: provide defense against abnormal cells and pathogens inside living cells This is called cell-mediated immunity

12. Humoral Immunity produces antibodies Antibodies produced by B cells of the Immune System recognize foreign antigens and mark them for destruction.

13. On your paper, distinguish between an antigen and an antibody.

14. Cell-mediated Immunity Body’s defense against its own cells when they have become cancerous or infected by viruses. Important in fighting infection caused by fungi and protists.

15. T cells divide and differentiate during cell mediated immunity Killer (cytotoxic ) HelperMemorySuppressor Tracks down and kills antigens Activates the killer T cells and B cells Similar to B cells – will cause a secondary response if body is invaded by the same antigen twice Shut down the killer cells once the pathogen is brought under control

16. Check your understanding: Complete the Learned Column of your K-W-L chart First, generally describe the function of the immune system. Next, list following cells on your paper: –B cells, plasma cells, helper T cells, killer T cells and macrophages –Write a description of the function(s) of each type of cell in preventing or fighting disease