The pressure exerted on the walls of the blood vessels or arteries during the systole is lowest if the blood vessels are of high compliance or low stiffness. Thus people who have elastic and highly compliant arterial walls have a narrow pulse pressure. Pulse pressure is the systolic pressure minus the diastolic pressure. This reflects low aortic wall tension. Low wall tension also means that the workload of the heart is low. The stiffer and harder the blood vessel walls, the wider the pulse pressure and more the heart has to work to pump blood into the arteries. In persons with stiffer arterial walls only a small fraction of each cardiac stroke volume can be utilized for blood circulation without increasing the blood pressure. The arterial wall stiffness depends on the structural elements within the arterial wall for example muscle, elastin and collagen. These bear the pressure on the wall when the wall is distended.