The systolic pressure is the pressure applied by the blood on the blood vessels during the contraction while the diastolic pressure is the pressure applied to the blood vessel during relaxation. Pulse pressure can be estimated by the difference between the systolic and diastolic pressure readings. It is measured in millimeters of mercury (mm/Hg). The systolic pressure is 120 mm/Hg and the diastolic phase is 80 mm/Hg. The pulse pressure counts to 40 mm/Hg.