Red blood cells are the most numerous blood cells in the peripheral blood and their main role is to transport oxygen and carbon dioxide for normal body metabolism. Mature red blood cells do not have a nucleus, but they contain a large amount of hemoglobin. Hemoglobin has a special structure, which can combine with oxygen to form oxyhemoglobin and flow with the blood circulation to the tissues and organs that need oxygen, which is separated from hemoglobin, and oxygen is taken in by the tissues and organs for the body to produce energy and maintain metabolism. The carbon dioxide produced by the body’s tissues and organs is combined with hemoglobin to form carboxyhemoglobin, which is transported with the blood circulation to the lungs and expelled from the body through respiration. Therefore, the main role of red blood cells is to transport oxygen and carbon dioxide. When the number of red blood cells decreases, the body will experience a decrease in oxygen-carrying capacity, and a series of symptoms of anemia will appear, such as pallor, dizziness, weakness, headache, dizziness, panic and chest tightness after activity.