Caption: Frog blood cells; the white blood cells are the round, dark ones in the center of the picture.
Red blood cells give your blood its red color. They carry oxygen from your lungs to all of the cells in your body. However, there is more to your blood than just red blood cells. More than half of your blood is made up of a liquid called plasma. It is mostly water, but it is very important. Plasma helps your blood to flow. It allows your heart to pump your blood through your blood vessels. Red blood cells make up most of the remaining part of your blood, but there are other important blood components. One of these is white blood cells.