If you have ever given blood, the nurses may have told you that your blood is made up of several different things including red blood cells, white blood cells, and plasma. Each part of your blood has a special job. Red blood cells carry oxygen to your body's cells and remove carbon dioxide. White blood cells help fight infection. Plasma is the liquid part of your blood that carries the red blood cells and the white blood cells. Iron is a mineral that is found in food and it is also found in your blood. Your body needs iron to make hemoglobin. Hemoglobin is what gives your blood its red color and it is also what helps carry oxygen to your cells. If you don't have enough iron in your blood, you can become very tired and your skin may look pale.