Fun puzzle! Just a quick note, the aorta is not IN the heart. The heart pumps blood out into the aorta, which is an artery that branches out thousands and thousands of times creating the route for blood to get to the rest of the body. After the oxygenated blood travels through the body and the O2 is used up, thousands and thousands of branches come back together into the vena cava that takes blood back to the heart. From there, blood is pumped to the lungs and gets oxygenated again, then comes back to the heart, then goes out through the aorta again. Your anatomy lesson for the day