Circulatory and respiratory system

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Across
  1. 5. a heavy colorless gas CO2 that is formed especially by the burning and breaking down of organic substances
  2. 6. Tiny air sacs at the end of the bronchioles
  3. 8. a colorless, odorless reactive gas, the chemical element of atomic number 8
  4. 9. a hollow muscular organ that pumps the blood through the circulatory system
  5. 10. channels that carry blood throughout your body
Down
  1. 1. delicate blood vessels that exist throughout your body
  2. 2. A tiny branch of air tubes in the lungs.
  3. 3. The airway that leads from the larynx (voice box) to the bronchi
  4. 4. the most common type of blood cell and delivers oxygen to the body tissues
  5. 7. One of a pair of organs in the chest that supplies the body with oxygen, and removes carbon dioxide from the body.