oxygen-poor
Blood flows through the heart in two separate loops. You can think of them as a left side loop and a right side loop. The right side of the heart collects oxygen-poor blood from the body and pumps it into the lungs, where it releases carbon dioxide and picks up oxygen. The left side carries the oxygen-rich blood back from the lungs into the left side of the heart, which then pumps the oxygen-rich blood to the rest of the body. The blood delivers oxygen to the cells of the body and returns to the heart oxygen-poor.