here are some links that are so helpful enshallah
for the digestive system
http://library.thinkquest.org/5777/dig1.htm
for the circulatory system
http://texasheart.org/HIC/Anatomy/Anatomy.cfm
and this site for all the systems together
http://www.kidskonnect.com/subject-index/31-health/337-human-body.html