respiratory system and circulatory system

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Across
  1. 2. the smallest blood vessel and it forms the connection between the vessels that carry blood away from the heart (arteries) and the vessels that return blood to the heart (veins).
  2. 4. this makes up 21% in the atmosphere
  3. 6. are blood vessels that carry blood away from the heart
  4. 9. he large air passages that lead from the trachea to the lungs.
  5. 10. are a type of blood vessel that return deoxygenated blood from your organs back to your heart.
  6. 11. used for breathing and smelling
Down
  1. 1. It plays a major role in breathing, as its contraction increases the volume of the thorax and so inflates the lungs.
  2. 3. a pair of organs in the rib-cage
  3. 5. It is naturally present in air and is absorbed by plants in photosynthesis.
  4. 7. The airway that leads from the larynx to the bronchi and it is also called a windpipe
  5. 8. it pumps blood around your body and it sends oxygen and nutrients to all parts of your body