In the Windkessel arterial model, which statement correctly describes the roles of the two elements, C and R?

• A. Capacitance stores arterial blood; Recoil controls venous return.
• B. Resistance represents peripheral resistance; Compliance represents arterial storage; together they shape pressure flow.
• C. Capacitance represents arterial storage and Conductance represents flow.
• D. Compliance controls blood viscosity.

Answer: (B)

The idea being tested is how the Windkessel model uses two lumped elements to represent the arterial system: a resistor for peripheral resistance and a capacitor for arterial compliance (storage). The resistor represents the impedance to outflow into the peripheral circulation; higher resistance means slower drainage and a more pronounced decay of pressure after each beat. The capacitor represents the ability of the arterial walls to stretch and store blood; this storage raises and then gradually releases pressure as the heart’s output fluctuates, smoothing the flow. Together, they shape the pressure–flow relationship by storing energy during systole and releasing it during diastole, while the resistance governs how quickly blood leaves the arterial reservoir. The other statements mix up roles (for example, venous return isn’t the primary function of arterial recoil in this model; conductance isn’t a separate element here; and compliance isn’t about viscosity).