I searched on google for some of the answers I was not sure of:
16. http://www.tutorvista.com/biology/parts-of-the-ears-and-their-functions
17. http://www.fi.edu/learn/heart/vessels/vessels.html
18. Blood picks up oxygen from the lungs
19. teeth and saliva
20. http://www.sciencebob.com/research/digestion.php
