All human blood vessels are connected. The blood vessels of the human body are divided into arteries and veins, and the arteries and veins are connected to each other through capillaries, and because of their wide distribution, the blood vessels are connected to each other, constituting a network of capillaries. Due to the high permeability of the capillary walls, many substances can enter the arterial blood through the capillaries for material exchange, the body can absorb nutrients through the arterial blood, and then discharged wastes into the venous blood. After a series of cycles, venous blood re-acquires nutrients and becomes arterial blood, and the cycle repeats itself. Therefore, we should pay attention to maintain good living habits to prevent thrombosis and the occurrence of cardiovascular and cerebrovascular diseases.