Circulatory system

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Across
  1. 4. Specialised cells that are electrically active in the heart act as a...
  2. 6. Which vessels carry blood to the heart?
  3. 7. Which artery leaves the right side of the heart?
  4. 8. Blood that enters the left side of the heart is...
  5. 12. What gas is carried by red blood cells?
  6. 13. Which valve connects the right atrium and ventricle?
  7. 14. What is the inner lining of veins and arteries made of?
  8. 16. How are dissolved substances carried in the blood?
  9. 17. What is the name of the circulatory system that transports oxygen, nutrients CO2 & waste?
  10. 18. How are capillaries specialised for efficient gas exchange?
  11. 19. Which vein enters the right atrium?
  12. 20. At what structure does diffusion occur to pass oxygen into the blood?
Down
  1. 1. Which vein enters the left atrium?
  2. 2. What is the name of the circulatory system that transports blood to the lungs?
  3. 3. Which valve connects the left atrium and ventricle?
  4. 5. What tissue is the outer layer of veins and arteries made of?
  5. 9. Which vessels carry blood away from the heart?
  6. 10. What is the channel in the middle of blood vessels called?
  7. 11. Which artery leaves the left side of the heart?
  8. 15. Blood that enters the right side of the heart is...
  9. 19. What structures stop backflow of blood?