RBC through the Heart

Red blood cells (RBCs) are also known as erythrocytes. They are how vertebrates deliver oxygen to cells in their bodies. The red blood cells travel through the circulatory system to exchange carbon dioxide with oxygen in the lungs. You are a RBC in the brain and need to travel through the heart to the lungs where you naturally drop your CO2 and pick up O2. Then travel back through the heart and into the body to give the body oxygen.