Fig. 2.

Capacity curve from Fig. 1 above (blue), with the linearized response (orange) around the operating point (blue diamond marker). The diamond marker denotes the point of optimal responsiveness, or operating point. Responsiveness is optimal when the tangent line has maximal slope around the current blood pressure. Regulating to optimal responsiveness requires either keeping current blood pressure near the operating point, or relaxing the baroreflex’s gain to widen the curve. The latter sacrifices performance (slope) at the operating point but provides greater resilience against uncertainty and perturbations. Note that the operating point refers to the point on the horizontal axis.