IMMUNITY

2. A long-lived lymphocyte that responds to the reintroduction of a specific antigen long after initial exposure is a .... cell.
4. A colourless fluid that bathes the cells; part of the lymphatic system.
8. Injection of a killed or weakened pathogen or pathogen part that stimulates the production of antibodies.
9. Largest organ in the lymphatic system; filters blood & contains lymphocytes and macrophages that destroy pathogens.
10. A single-celled pathogen that can cause disease like tetanus; can be round, rod or spiral shaped.
12. Active immunity results from the development of ...... in response to antigens; produced by B lymphocytes as a Y-shaped protein.
15. The ability of an organism to resist disease through natural or acquired resistance.
16. Small bean-shaped glands found in the lymphatic system containing white blood cells; can filter bacteria from lymph fluid. lymph ....
17. Near-colourless cells of the immune system that circulate in the blood & lymph are .... blood cells.

1. Type of white blood cell that matures in the thymus; have T cell receptors; they hunt down & destroy cells infected with pathogens; a T .....
3. Passive immunity is offered to babies when they receive antibodies from their mother's .......
5. Tiny thin-walled blood vessels from which white blood cells can leave the blood to enter the tissues.
6. General name of a disease-causing organism including bacteria, virus and fungus.
7. A white blood cell that can engulf and absorb bacteria by phagocytosis.
11. Cell organelle in phagocytes containing enzymes that digest and destroy ingested pathogens.
13. An additional dose of a vaccine needed to periodically boost the immune system is a .... shot.
14. A foreign substance which induces the production of antibodies; found on the surface of pathogens.