The circulatory system is responsible for moving blood throughout the body . during this process , oxygen , carbon dioxide , and other nutrients are circulated to all parts of the body . students model this by filling rubber tubing with a liquid . they squeeze the tubing to move the liquid . what are the students modeling ? a the squeezing represents the esophagus pushing food down into the stomach . b they are simulating how blood moves through vessels by constriction of the heart and vessels . c the students are showing food traveling from the large intestine to the small intestine d attachment of muscles to the skeletal system is represented in this activity .