Difference Between Systolic and Diastolic Pressure

Systolic vs Diastolic Pressure

The pressure on the arterial wall during the phase of the heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries is called systolic pressure. The pressure on the arterial wall when the heart muscle relaxes and allows the chambers to fill with blood is called diastolic pressure.

Pressure is the word commonly used to refer the arterial blood pressure. The blood circulation is mainly carried out by the heart, which acts as a pump. When the heart pumps, the blood will forcefully directed to aorta (the main vessel starts from the left ventricle of the heart to give blood to organs); when the pressurised blood enter the aorta it exerts the pressure in its wall, and aorta has a elastic capacity to an extend and distend a bit. A pressure is generated by this heart muscle contraction to the blood passed on to the wall of aorta. This pressure at the end of the contraction of the heart is called systolic pressure. After that again the heart will be relaxed and the blood supply to the aorta stops and the valves at the beginning of aorta closes. At this time the aorta comes back to normal position from the distended position. This recoiling will again give pressure to the blood. The pressure in the vessel wall during the relaxation of the heart is called diastolic pressure.

In a normal individual the systolic pressure will be 120 mm mercury. The diastolic pressure is 80 mm mercury. The blood pressure usually measured by Sphygmo manometer. However, now electronic blood pressure measuring apparatus are in the market. The systolic and diastolic pressure will vary depending on the individual’s activity. The systolic pressure may rise to higher level during heavy work, fearing situation etc. However these levels come back to normal with the rest.

Females may have less systolic and diastolic pressure. They usually have 110 mm Hg (Mercury’s chemical symbol) systolic pressure and 70 mm Hg diastolic pressure. Children also have less systolic and diastolic pressure, it depends on their age and activity.

Continuous high reading of blood pressure is called as HYPERTENSION. Like diabetic, this also a chronic disease and need continuous treatment.

Persistent low reading of blood pressure is called as HYPO TENSION.


The systolic pressure is the pressure on the arterial wall during the heart muscle contraction. Diastolic pressure is the pressure when heart is relaxing.