body systems 99

4. the force of blood pushing against the blood vessel walls
5. a tube of neutrons that runs along the spine
8. groups of organs that perform a body function
9. the main organs of the respiratory system
12. the system that enables you to breathe
14. structures made up of different types of tissues that all work together
15. the body system that gets rid of some of the waste in your body produces and also maintains fluid balance
16. the muscle that acts as the pump for the circulatory system
17. a body system consisting of bones and the tissues connecting them
18. cells that carry electrical messages

1. large muscle at the bottom of the chest
2. the basic building blocks of life
3. all the muscles in your body
6. the control and communication system of the body
7. places where one bone meets another
10. the process by which your body breaks down food into small nutrient particles
11. a system that allows the body to move blood to and from tissues
13. groups of similar cells that do the same kind of work