Body Systems

4. _____ are born with 300 bones?
6. The circulatory system is made up of ___?
7. Muscles make up approximately ___% of total weight.
8. the brain and the spinal cord are the _____?
12. The nerves that go through the whole body make up the ____?
14. Located only in the heart, _____ muscle pumps blood around the body.
15. The ______ circulation carries blood from the heart to all the other parts of the body and back again.
17. Your skeleton is made of more than 200 ____?
18. air enters the respiratory system by the nose and the ____?
19. the human brain weighs _____ pounds?
20. The mitral ____ separates the left atrium from the left ventricle.

1. The _______ circulation is a short loop from the heart to the lungs and back again.
2. what system allows us to breathe?
3. The ____ is the hardest-working muscle in the body.
5. The brain and the spinal cord are protected by ___?
9. The ear contains the _____ muscles in the body alongside the smallest bones.
10. this system contains the face body part mouth and ?
11. The longest bone in the body is in your?
13. The smallest bone in the body is in your?
16. the lungs contain ______ that allow them to inflate and deflate without loosing shape.