Immune System

3. thin-walled, valved structure that transports lymph around the body
4. a secretion that covers cells that line our respiratory and digestive systems and helps trap pathogens that enter the body
7. a specific protein produced when an antigen enters the body
9. any substance that triggers your immune system to produce antibodies or mount a targeted immune response
10. small, bean-shaped structure that contains white blood cells that identify and destroy harmful invaders before they can spread

1. a small, specialized gland in the upper chest that acts as the master training center for your immune system
2. another name for a white blood cell
3. a type of white blood cell that act as the primary defenders in your immune system
5. an abdominal organ that filters the blood, recycles old red blood cells, and stores platelets and white blood cells
6. soft, spongy tissue inside your bones that acts as the body's primary blood cell factory
8. a pair of soft tissue masses at the back of the throat that trap germs that are breathed in
11. specialized white blood cells that protect your body by ingesting (eating) harmful foreign particles, bacteria, dead cells, and cellular debris