Red blood cells are the most numerous blood cells in the human body, and their main function is to transport oxygen and carbon dioxide. When a person breathes, he inhales oxygen into the lungs, where the oxygen combines with hemoglobin in the red blood cells to form oxyhemoglobin, which is transported to various tissues and organs with the blood circulation for use by the body’s tissues and organs. At the same time, the carbon dioxide produced by various tissues and organs and hemoglobin to form carboxyhemoglobin, transported to the lungs through the blood circulation, with the respiration out of the body. Therefore, the main physiological role of red blood cells is to transport oxygen and carbon dioxide. If the number of red blood cells decreases, the ability of red blood cells to transport oxygen will decrease, and the human body will experience symptoms of hypoxia, which are manifested as dizziness, fatigue, pallor, panic and chest tightness, laziness, etc., which are the symptoms of anemia.