In an unfortunate accident, a young man is struck in the leg by a bullet that tears through the femoral artery just above his right knee. The subsequent blood loss leads to a rapid drop in blood pressure. Baroreceptors in the aorta monitor blood pressure and send signals to the vasomotor center of the brain. In this case, the vasomotor center will increase its sympathetic stimulation of the blood vessels which will cause them to constrict. This constriction leads to an increase in blood pressure. This is a description of __________.