The digestive system works very closely with the circulatory system to
get the absorbed nutrients distributed through your body. The
circulatory system also carries chemical signals from your endocrine
system that control the speed of digestion.
The digestive system also works in parallel with your excretory system
(kidneys and urination). While the digestive system collects and removes
undigested solids, the excretory system filters compounds from the
blood stream and collects them in urine. They are closely connected in
controlling the amount of water in your body.
Hope That Helps!