The Immune System

1. The Immune System http://kidshealth.org/kid/htbw/_bfs_ISmoviesource.html

2. Terms to know • Pathogens--- organisms that cause disease • Antigen--- a marker molecule on a cell that the immune system uses to recognize a pathogen • Antibody--- a chemical that helps destroy a specific kind of pathogen by locking onto a specific marker molecule

3. Three lines of defense

4. 1. Barriers • Skin—forms a physical and chemical barrier • Breathing passages---mucus and cilia trap and remove pathogens (sneeze or cough) • Mouth and Stomach---most pathogens you swallow are destroyed by chemicals in your salivia or stomach acids

5. 2. Inflammatory response • Fluid and certain types of white blood cells leak from blood vessels into nearby tissues. • The white blood cells (phagocytes) then fight the pathogen. • During the inflammatory response, the affected area becomes red, swollen, and warm. Fever may also occur.

6. 3. Immune response • The cells of immune system can distinguish between different kinds of pathogens. The immune system cells react to each kind of pathogens with a defense targeted specifically at that pathogen. • White blood cells that target specific pathogens are called lymphocytes.

7. Two major kinds of lymphocytes • T-cells identify pathogens by recognizing their antigens • B-cells produce chemicals called antibodies

8. HIV • Human Immunodeficiency Virus • Spread through bodily fluids only • HIV works like a trojan horse----HIV sneaks inside the T cell and destroys it. HIV goes undetected from the immune system.