Another regulatory reflex involves pressure receptors located in the right atrium. In this case, an increase in right a trial pressure signals the cardiovascular control center that an increase in venous return has occurred; hence, to prevent a backup of blood in the systemic venous system, an increase in cardiac output must result. The cardiovascular control center responds by sending sympathetic accelerator nerve impulses to the heart, which increase heart rate and cardiac output. The end result is that the increase in cardiac output lowers right a trial pressure back to normal, and venous blood pressure is reduced