There are always two pressures expressed in blood pressure ranges, the systolic and the diastolic pressure.
Blood pressure ranges are usually written using the systolic number before or above the diastolic number, for example 120/80 mmHg. The systolic pressure, which is the first number shown, the 120 in the example above, is the pressure reading as the heart pumps blood out from the ventricle into the veins. The diastolic pressure, 80 in the above example, and as illustrated in the blood pressure chart, is the resting pressure, which is between beats when the pressure decreases before the next heart pumping action.
For young adults aged 20 to 40, the normal, healthy blood pressure ranges are 120/80 but there is also normal to high, 130/85 and normal to low, 110/75. The high blood pressure ranges for this age group progress in stages from 140/90 up as high as 210/120. The low blood pressure ranges go from 90/60 to a dangerously low level of 50/33. By the age of 50, the average, normal blood pressure ranges have risen to 129/85 and at 60, there is a further increase in the average normal range to 134/87.
High blood pressure is termed hypertension, low blood pressure is hypotension. If there is no obvious cause for hypertension, which is often the case, it is called primary hypertension. Secondary hypertension, the term given to only 5 to 10% of cases, can be caused by a number of factors, amongst them kidney or heart disease and hardening of the arteries. More blood pressure information.
Understanding High Blood Pressure Video
Reference for: What are Blood Pressure Ranges?