Immune system

3. (v.) to tear, split, or open (something) quickly or violently
8. (n.) a choice that you make about something after considering all the possibilities
9. (adj.) ends in -ly; means very dangerous for your body and can kill a living organism
12. a huge cell of the immune system that kills bacteria
13. (n.)a process in your body when a particular part of it suddenly becomes bigger
15. (n.) a smaller cell of the immune system that helps to fight bacteria during the second and third stages of the battle
19. (n.) an example of smth that is stored for future analysis or research
20. (ph.v) to ask for help
21. (n.) an extremely small particle that causes a disease and that spreads from one person or animal to another

1. a substance found in foods (such as meat, milk, eggs, and beans) that is important for building your muscles
2. (ph.v) to throw the ball into a game; to join a system and start working
4. (adj.) very important; an element without which the hole system won't work
5. the red liquid that circulates in our body
6. (v.)to produce
7. (n.) a covering piece of material or a part that lies over or under another
10. (n.ph.) a small, oval-shaped, rounded mass of tissue in the body which cleans and filters the lymph
11. (n.) a group of single-celled microorganisms that often cause disease
14. (v.) to gather smth for the purpose of storing or analysing in the future
16. (n.) the necessity of doing smth very quickly
17. (n.) O2;smth that we need for breathing
18. (v.) to remain alive; to continue to live after a disaster
20. a hundred million