Why is blood circulation in the human heart called double circulation?

(N/A) The blood circulation in the human heart is called double circulation because the blood passes through the heart twice in one complete cycle of the body.
First,deoxygenated blood enters the right half of the heart to be pumped to the lungs for oxygenation.
Second,oxygenated blood returns to the left half of the heart to be pumped to the rest of the body.
This separation ensures that oxygenated and deoxygenated blood do not mix,making the process highly efficient.