tailieunhanh - Ebook Cardiovascular physiology (10th edition): Part 2

(BQ) Part 2 book "Cardiovascular physiology" presents the following contents: The arterial system, the microcirculation and lymphatics, the peripheral circulation and its control, control of cardiac output - Coupling of heart and blood vessels, coronary circulation, special circulations, interplay of central and peripheral factors that control the circulation. | THE ARTERIAL SYSTEM OBJ ECTIVES 1. Explain how the pulsatile blood flow in the large arteries is converted into a steady flow in the capillaries. 2. Discuss arterial compliance and its relation to stroke volume and pulse pressure. 3. Explain the factors that determine the mean systolic and diastolic arterial pressures and the arterial pulse pressure. 4. Describe the common procedure for measuring the arterial blood pressure in humans. THE HYDRAULIC FILTER CONVERTS PULSATILE FLOW TO STEADY FLOW The principal functions of the systemic and pulmonary arterial systems are to distribute blood to the capillary beds throughout the body. The arterioles which are the terminal components of the arterial system regulate the distribution of flow to the various capillary beds. In the region between the heart and the arterioles the aorta and pulmonary artery and their major branches constitute a system of conduits of considerable volume and distensibility. This system of elastic conduits and high-resistance terminals constitutes a hydraulic filter that is analogous to the resistancecapacitance filters of electrical circuits. Hydraulic filtering converts the intermittent output of the heart to a steady flow through the capillaries. This important function of the large elastic arteries has been likened to the Windkessels of antique fire engines. The Windkessel in such a fire engine contains a large volume of trapped air. The compressibility of the air trapped in the Windkessel converts the intermittent inflow of water to a steady outflow of water at the nozzle of the fire hose. The analogous function of the large elastic arteries is illustrated in Figure 7-1. The heart is an intermittent pump. The cardiac stroke volume is discharged into the arterial system during systole. The duration of the discharge usually occupies about one third of the cardiac cycle. In fact as shown in Figure 4-13 most of the stroke volume is pumped during the rapid ejection phase. This phase constitutes .