http://www.google.com.br/search?q=sistema+circulatorio&hl=pt-BR&safe=off&prmd=imvnsb&tbm=isch&tbo=u&source=univ&sa=X&ei=Z6J4T_zoMMfEtgf82vzgDg&ved=0CEMQsAQ&biw=1280&bih=709&sei=TKN4T7n1Kce2twfnw-HkDg

http://pt.wikipedia.org/wiki/Sistema_circulat%C3%B3rio

http://www.sobiologia.com.br/conteudos/Corpo/Circulacao5.php

http://www.youtube.com/watch?v=XEeW7F-P9uc&feature=related