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A negative feedback system which buffers short-term changes in blood pressure. Increased pressure stretches blood vessels which activates PRESSORECEPTORS (baroreceptors) in the vessel walls. The net response of the central nervous system is a reduction of central sympathetic outflow. This reduces blood pressure both by decreasing peripheral vascular resistance and by lowering cardiac output. Because the baroreceptors are tonically active, the baroreflex can compensate rapidly for both increases and decreases in blood pressure.