Diagram

Red blood cells journey

Red blood cells start at the heart, then travel the Pulmonary artery and to the lungs, where the blood cells get oxygentrated. The red blood cells return to the heart where they are the sent through the atora, after that they branch off into arteries that takes the blood to many different parts of the body, it is when they reach these body parts, that they start giving the oxygen to the organ while in a single file. They then travel through the veins on there way back to the heart, before they get to the heart they travel through the Spleen and Liver, which take away old blood cells... After that they return to the heart and start their journey again.