The arterial vasculature is generally divided into large arteries, medium arteries, small arteries and micro-arteries, and their roles are to maintain diastolic blood pressure, regulate blood flow to various organs, regulate peripheral vascular resistance, and promote material exchange, respectively. 1. Large arteries: generally refers to the aortic arch, thoracic aorta, abdominal aorta and its branches of the relatively large blood vessels, thick walled blood vessels, there can be obvious expansion, in the systolic period of the heart by the expansion of the capacity, in the diastolic period of elasticity contraction, to ensure that the blood flow uninterruptedly, to maintain diastolic blood pressure. 2. Middle arteries: blood vessels between large arteries and small arteries, which can be dilated and contracted through neural and humoral regulation, distributing blood to various organs and regulating blood flow to each organ. 3. Small arteries and micro-arteries: the lumen of the blood vessels is small and the resistance to blood flow is large, which can promote the exchange of substances in the capillaries and regulate the peripheral resistance of the blood vessels.