Blood circulates throughout our bodies pumped along by the heart.
With each beat of the heart the pressure rises and after each beat it falls. The maximum pressure after a beat of the heart is called the systolic pressure and the low point of pressure is called the diastolic pressure. There are many causes of high blood pressure. Systolic pressure greater than 140 mm Hg or a diastolic pressure greater than 90 mm Hg is considered hypertension. Most people who develop hypertension have what is known as essential hypertension.