I am doing a crossword puzzle for the Circulatory and respiratory systems review. If you can say them all I will give you 22 points. If you need to know how many letters ask in comments.

3.Pumps blood to heart

6.What returns fluid that leaks from capillaries back to the circulatory system

7. branching system of tubes which sends air to the alveoli

9. contains blood with little oxygen and a lot of carbon dioxide

15. a dangerous tumor in the respiratory system.

16. muscle that relaxes when you exhale.

19.moves substances through the body.

Down:

5.Separates the atria from the ventricle ; keeps blood flowing one way

8. thin walled blood vessel  that allows for gas exchange

11. hair like structures that line the trachea and nose

12. receives blood from the lungs

17. movement of air in and out of lungs

18 location of gas exchange in the lungs

20. oxygen transport blood component