Definition: Measuring your blood pressure yields two values -- the systolic and diastolic pressure. The blood pressure reading is recorded like this: 120/80, with the systolic pressure on top and the diastolic pressure on the bottom. Both values represent the pressure in millimeters of mercury, or mmHg.
The systolic pressure, the top number in the blood pressure reading, is the pressure the blood exerts in the artery when the heart muscle is beating.
The diastolic pressure, the bottom number in the blood pressure reading, is the pressure the blood exerts in the artery in between heart beats, while the heart muscle is relaxing.
Both the systolic and the diastolic blood pressures are important in determining whether your blood pressure is normal, elevated, or low.
