6. This system fights pathogens (germs) and produces and stores white blood cells. a. immune b. muscular c. endocrine d. integumentary

5. This system breaks down food into nutrients that the body can absorb. a. digestive b. excretory c. reproductive d. immune

7. This system supports the body and protects vital organs. a. skeletal b. muscular c. circulatory d. nervous

9. Which system sends electrical messages that helps control the body's responses to internal and external changes? a. nervous b. endocrine c. reproductive d. integumentary

11. What two systems work together to supply the body with oxygen? a. respiratory and muscular b. respiratory and circulatory c. circulatory and digestive d. muscular and digestive

3. Which system absorbs oxygen and releases carbon dioxide? a. respiratory b. excretory c. endocrine d. immune

1. Which system acts as a barrier from the sun and helps regulate body temperature? a. integumentary b. muscular c. digestive d. circulatory

2. Which system controls voluntary and involuntary movement? a. muscular b. skeletal c. immune d. excretory

12. Which two body systems work together to break down food into energy and rid the body of the waste produced during this process? a. Skeletal and endocrine b. Digestive and excretory c. Nervous and immune d. Muscular and skeletal

4. This system transports oxygen and nutrients around the body. a. circulatory b. respiratory c. skeletal d. digestive

10. The nervous system helps the respiratory system by__ a. carrying oxygen to lungs b. sending the message to diaphragm to contract c. protecting and supporting the heart d. breaking down nutrients needed by lung tissue

8. This system sends chemical messagengers (hormones) that regulate growth, development, and metabolism. a. endocrine b. nervous c. immune d. skeletal