22 12 Across 1. Close circuit of tubes through which blood flows 3. Where exchange of materials (nutrients gas waste) takes place 7. Movement of blood through the tissues ofthe heart 9. Responsible for carrying blood back tothe heart 10. It contains oxygenated blood 11. It pumps blood throughout the body. 12. Gas that is essential to life. Down 2. Movement of blood from the heart to the rest of the body 4. Organ system in-charge of gas exchange 5. Movement of blood from the heart to the lungs 6. Internal circulating medium of the body 8. Organ system responsible for the circulation of the blood​