Shown here are examples of visceral or autonomic pathways that allow the CNS to regulate blood pressure (BP) and heart rate (HR). When blood pressure (BP) declines, pressure receptors (baroreceptors) in the wall of the aortic artery detect the change and a corrective, involuntary reflex begins. Action potentials (= electro-chemical impulses) are generated in autonomic sensory (= afferent) neurons and conducted to the cardiac regulatory center in the brainstem. From the brainstem, impulses are conducted down the spinal cord by CNS neurons. The impulses are transmitted to motor (= efferent) neurons in the spinal cord, which conduct them to the heart. On their arrival, the impulses stimulate the heart to beat faster.