Chapter 14: Systemic Circulation & Blood Pressure Regulation

Systemic Circulation & Blood Pressure Regulation establishes that mean arterial pressure is determined by the interaction between cardiac output and systemic vascular resistance, while pulse pressure is primarily a function of stroke volume and arterial compliance. The text details the arterial pressure waveform and explains how the non-linear compliance of arteries results in increased stiffness at higher pressures, a phenomenon that underpins the development of isolated systolic hypertension in older adults due to arteriosclerosis and age-related vascular changes. Clinical assessment techniques are reviewed, specifically the indirect measurement of blood pressure using sphygmomanometry and the interpretation of Korotkoff sounds caused by turbulent flow. The chapter contrasts the resistive arterial system with the highly compliant venous system, which contains the majority of total blood volume and acts as a dynamic reservoir. This distinction is critical for explaining how gravitational forces during standing cause venous pooling, thereby reducing central venous pressure, venous return, and cardiac output via the Frank-Starling mechanism. A significant portion of the text is dedicated to the integration of cardiac and vascular function, utilizing graphical analysis to demonstrate how the cardiac function curve and vascular function curve intersect to determine the equilibrium point for cardiac output and central venous pressure. This framework is used to predict hemodynamic shifts caused by variables such as changes in blood volume, arteriolar resistance, and myocardial contractility, as well as compensatory mechanisms in heart failure. Finally, the chapter addresses the inflammatory pathophysiology of atherosclerosis involving oxidized LDL and plaque rupture, while also discussing the pharmacology of statins and their potential adverse effects, such as myopathy and rhabdomyolysis.