Christmas Nervous system

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Across
  1. 3. The pole that Santa lives at
  2. 4. Blood vessel that takes blood from the heart to the body
  3. 6. Title character from A Christmas Carol
  4. 8. Organ that pumps blood around the body
  5. 10. The bottom and larger chambers in the heart
  6. 11. The junction between two neurons
  7. 14. Part of the nervous system which controls voluntary actions
  8. 16. Reindeer with the red nose
  9. 18. Single ice crystal falling from the sky
  10. 20. Blood travels to and from the lungs via the _____ system
Down
  1. 1. The muscles that move the ribcage during breathing
  2. 2. Blood vessel that takes blood from the body back to the heart
  3. 5. Examples include acetylcholine, nor-adrenaline and glutamate
  4. 7. Part of the nervous system that includes the brain and the spinal cord
  5. 9. Santa's last name
  6. 11. The ions that move across the membrane during depolarisation
  7. 12. The nervous systems fight-or-flight division
  8. 13. The most famous snowman
  9. 15. Tiny sacs in the lungs where gas exchange occurs
  10. 17. Muscle below the lungs that helps us breathe
  11. 19. The part of the cardiovascular centre that controls increasing heart rate