Answer :
the circulatory system is the system of the blood flow in the body. it is called the circulatory system because it flows in a cycle like motion repeating the same path in circulation.
Circulus relates to the circulatory system because the organ systems' job is to pump blood and oxygen throughout your body. It "circles" your body because blood is pumped by your veins to your other organs inside of you. Eventually, that used blood goes to your lungs to be filled with oxygen again and then gets pumped around by your heart to your other organs again, again, and again - it's a cycle.