Question

why is the heart called a double pump

Answer 1

Although your heart is one organ, it acts as a double (2; twice) pump.

FIRST "PUMP":
The first pump carries blood with a lack of oxygen to your lungs to get rid of carbon dioxide and get more oxygen. After that, the blood is carried back to your heart.

SECOND "PUMP":
The second pump delivers the blood with that has enough oxygen throughout your body.

Answer 2

Your heart is a single organ, but it acts as a double pump. The first pump carries oxygen-poor blood to your lungs, where it unloads carbon dioxide and picks up oxygen

Then delivers oxygen-rich blood back to your heart. The second pump delivers oxygen-rich blood to every part of your body.

Hope this helped!