1. Immune System
S7L2e. Students will describe the basic functions of human body systems.

2. What is your immune system?
Your immune system is the complex group of defenses that work against harmful substances and all types of disease-causing organisms
Your immune system includes your skin, respiratory, digestive, and circulatory systems

3. What are the major organs of the immune system?
Tonsils
Skin
Cilia
White blood cells

4. What are pathogens?
Disease causing organisms

5. How does your digestive system defend your body against disease?
Saliva in your mouth contains substances that kill bacteria
Enzymes in your stomach, pancreas, and liver help destroy pathogens

6. How does your circulatory system defend your body against disease?
White blood cells surround and digest foreign organisms and chemicals
If the white blood cells cannot destroy bacteria fast enough, you could develop a fever, which slows the growth of pathogens and speeds up your body’s defenses

7. What are antigens?
Molecules that are foreign to your body

8. What is an antibody?
Antibodies are proteins made in response to antigens
Antibodies make antigens useless, therefore protecting your body against antigens