People often talk about blood pressure, then, how is blood pressure formed? Blood pressure is the measured pressure of blood to the walls of blood vessels, which can be divided into arterial blood pressure, capillary blood pressure and venous pressure, and the commonly said blood pressure refers to the arterial blood pressure. The reason why circulating blood can flow from large arteries to small arteries, capillaries, small veins and large veins in order is that there is a decreasing blood pressure difference between blood vessels. To maintain a certain blood pressure, three basic factors are required. 1. The interaction of the power generated by the heart contracting to eject blood and the resistance to the flow of blood. When the heart contracts to eject blood, it acts directly on the arterial blood vessel wall, which is the direct source of arterial pressure. Therefore, when the heart stops, no blood pressure can develop. In addition, clinically we often see hypertensive patients with extensive myocardial infarction have their blood pressure return to normal, which is due to a significant reduction in the heart’s ability to eject blood. When the blood flow through the blood vessels, especially through the tiny arteries, due to the friction between the various substances of the blood components and between the blood and the walls of the blood vessels, there will be a lot of resistance. Thus, the blood injected into the large arteries by each contraction of the heart cannot all pass rapidly through the small arteries, but a part of it is stored in the arterial system, filling and compressing the walls, forming arterial blood pressure. Thus, the power generated by the heart’s systolic ejection and the peripheral resistance to blood flow in the blood vessels are the two fundamental interdependent conditions for the formation of arterial blood pressure. If there is no peripheral resistance, all the blood ejected from the heart will flow to the periphery, i.e., the energy released by the heart contraction can be fully expressed as kinetic energy of blood flow, and thus the lateral pressure on the vessel wall will not increase. Therefore, blood pressure is equal to the product of cardiac output and peripheral resistance. Lu Xiaoyan, Department of Integrative Cardiology, China-Japan Friendship Hospital 2, there must be sufficient circulating blood volume. If the circulating blood volume is insufficient, the blood vessel wall is in a state of collapse, and the basis for the formation of blood pressure is lost. As commonly known as hemorrhagic shock, is due to excessive bleeding, the effective blood volume is insufficient due to the reduction of blood pressure. In addition, a large amount of sweating, diarrhea and long-term non-diet, can also be due to insufficient blood volume and lower blood pressure. 3. The elasticity of the wall of large blood vessels. When the heart contraction, can produce pressure on the arteries, why diastolic blood pressure does not immediately drop to zero, but still maintain a certain blood pressure value? This is due to the elastic retraction effect of the large arteries. In the process of contraction of the heart, the blood in the aorta cannot all flow away quickly because of the peripheral resistance. In general, the left heart ejects 60-80ml of blood into the aorta during each contraction, only about 1/3 of it flows to the periphery, and the remaining 2/3 is temporarily stored in the aorta and the aorta, under the action of blood pressure, the elastic fibers of the aorta wall are stretched, the lumen is enlarged, and part of the energy released by the heart contraction is temporarily stored in the aorta wall in the form of kinetic energy converted into potential energy. When the heart diastolic, the aortic valve closed, due to the ejection of blood stopped, blood pressure fell, the original elongated elastic fibers in the wall of the aorta will be retracted, so that the lumen of the artery becomes smaller, and potential energy is converted into kinetic energy, the part of the blood stored in systole will continue to push to the periphery, and the aortic pressure in diastole can still be maintained at a high level. As can be seen, the intermittent ejection of blood from the left heart becomes a continuous flow in the arteries due to the action of the elastic receptor vessels, which propel blood flow and maintain a certain lateral pressure of blood against the vessel walls. When the heart is systolic, the arterial blood pressure rises rapidly, and in the middle of cardiac systole, the highest value reached by the rise in blood pressure is called systolic pressure (or high pressure); when the heart is diastolic, the arterial blood pressure falls rapidly, and in the end of cardiac diastole, the lowest value reached by the fall in blood pressure is called diastolic pressure (or low pressure). The difference between systolic pressure and diastolic pressure is called pulse pressure (pulse pressure), normal people about 30 to 40 mmHg. the average value of the blood pressure of each instant in a cardiac cycle, called the average arterial pressure. It is the average pushing force that continuously pushes the blood forward during – a cardiac cycle. Therefore, it can more accurately reflect the functional state of the heart and blood vessels, and is calculated as follows: Mean arterial pressure = diastolic pressure x 1/3 x pulse pressure Thus, it can be seen that blood pressure is formed on the basis of sufficient circulating blood volume, when the heart contracts and ejects blood, the lateral pressure of blood on the vessel wall, and the elasticity of the aorta transforms energy storage from kinetic energy to potential energy and then to kinetic energy, thus maintaining the lateral pressure of blood on the vessel wall. -This maintains the lateral pressure of blood on the blood vessel wall and promotes blood flow to ensure normal blood pressure. Warm tip: The blood pressure is usually referred to as arterial blood pressure, using mmHg as the unit of measurement. Commonly used blood pressure measuring instruments include mercury column meters and electronic measuring instruments. The blood pressure of the left and right arms, upper and lower extremities of a normal person is not exactly the same, usually, the right arm is 5-10mmHg higher than the left arm blood pressure, and the lower extremities are 20-40mmHg higher than the upper extremities.