Autonomic Control of the Heart Rate

During exercise, the heart rate needs to increase in response to an increased demand for oxygen. This is controlled by a region in the brain called the medulla oblongata.There are two centres in the medulla oblongata: the cardiac acceleration centre and the vagal centre.In response to stimulation, the central nervous system activates the cardiac acceleration centre which increases heart rate directly via the sympathetic accelerator nerves which sends impulses to the sinoatrial node to increase the heart rate.The vagal centre decreases the heart rate via the parasympathetic nervous system. It sends impulses along the vagus nerve to the SAN to decrease the heart rate.The cardiac centre in the medulla receives impulses from chemoreceptors and pressure receptors in the walls of the carotid artery and aorta.