Blood is pumped at high pressures in arteries from the heart to ensure that all parts of the body receive adequate blood flow. Capillary beds, however, would hemorrhage under direct arterial pressures. How does the design of the circulatory network contribute to reducing blood pressure to avoid this scenario?
A. Blood flow through the capillaries is essentially frictionless, and this reduces the amount of pressure on their walls. B. The total cross-sectional diameter of the arterial circulation increases with progression from artery to arteriole to capillary, leading to a reduced blood pressure. C. Fluid loss from the arteries is high enough that pressure drops off significantly by the time blood reaches the capillaries. D. Capillary beds have the thickest walls of any blood vessel to resist these high pressures.