Most of us have had our blood pressure measured at some time and you will recollect an inflatable cuff being placed on your upper arm, attached by a tube to a measuring gauge.  These days, more often than not, the gauge will be an electronic gizmo which gives a digital reading.  The older style gauge comprises a glass tube containing mercury, looking rather like a giant, thick thermometer, mounted in a protective box.  
Measurements are taken in millimetres of mercury (mmHg) and the modern devices are calibrated to show this, even though no mercury is involved; much safer and cheaper. Two separate measurements are always taken:
Systolic blood pressure
Often called by its shortened version - "Systolic", is the higher of the two numbers that the doctor will tell you.
Systolic blood pressure is the force exerted on the walls of the blood vessels while the heart is contracting - that is, the muscles are “squeezing” the blood out from your heart.
Diastolic blood pressure
Shortened version - "Diastolic", is the force exerted on the blood vessels while the heart is at rest - that is before the next "pump" of refreshed blood leaving the heart.
High Blood Pressure - Low Blood Pressure - Normal?

Every individual's blood pressure tends to vary greatly and can actually change from one heart beat to the next. In order to determine a person's average blood pressure it is necessary to take more than one measurement at various times of day over a period of time.

If a person maintains normal blood pressure he or she is less likely to develop cardiovascular problems or other health complications. Blood pressure that is abnormally high or low can lead to potentially fatal problems. Therefore it is very important to make sure that you or your health care provider checks your blood pressure regularly.

Healthy Levels

Generally the older you are the higher your blood pressure is likely to be but starting at the ideal level, healthy blood pressure has a systolic measurement of between 90 and 119.  It has a diastolic measurement of 60-79.  People with low average measurements are less prone to the health complications associated with hypertension and hypotension.  Children have lower blood pressure than adults.

Prehypertension

If more than one test indicates that you have a blood pressure reading of between 120/80 and 139/89 you have what is called prehypertension. This means that you are at risk of developing hypertension.  If you have prehypertension you probably need to make certain lifestyle amendments in the interest of maintaining your health.  This is probably best done under the supervision of your doctor but is likely to include a review of your weight and maybe dieting, an exercise regime and avoiding nicotine, alcohol, caffeine, sugar, saturated fats and sodium wherever possible.

Hypertension

There are two stages of hypertension or high blood pressure. Stage one hypertension is a measurement between 140/90 and 159/99. There are various prescription medications that can be taken to correct the problem of stage one hypertension and the same lifestyle amendments that are used to treat prehypertension are probably necessary.  Generally, people with hypertension are at increased risk of heart attack, stroke, heart failure, aneurysm, kidney failure and eye problems.

Stage two hypertension is a measurement of 160/100 or more.  People who have elevated hypertension are at particularly high risk of the aforementioned health problems. And most probaly require urgent medical treatment if they are to avoid having a heart attack or stroke.

Hypotension

Hypotension is the term used to describe low blood pressure.  A low measurement varies from one individual to the next.  In other words, a person with a diastolic pressure of 60 may experience no adverse symptoms while the next individual may start to react badly if theirs reaches as low as 70.  A severe case of hypotension is dangerous because it means that the oxygen and vital nutrients in the bloodstream are not reaching vital organs. This can cause blackouts, which are sometimes mistaken for a stroke or in more extreme cases, organ damage or failure.  In the most extreme cases it can cause coma or death.

Hypotension has numerous potential causes including pregnancy, certain medications, blood loss, inadequate nutrition, dehydration and septicaemia.  You can reduce your risk of developing hypotension by eating a healthy diet with sufficient calories, vitamins and minerals and drinking plenty of water.  One of the reasons one is often reminded of the importance of breakfast is to avoid the possibility of faintness and blackouts.  Even those on low calorie diets are well advised to ensure they eat breakfast at the start of their day.

Monitor Your Blood Pressure

Doctors often take your blood pressure as a routine matter, irrespective of why you visit them.  However, not all doctors do this and secondly, some people are either lucky and have only occasional need to visit their doctor.  Even worse, some should visit their doctor but do not.  Either way, there can be no excuse these days to not check your blood pressure as electronic, simple-to-use Blood Pressure Monitors are readily available and if you use the Internet, you can read about them in peace before you choose.
These electronic Blood Monitors are so simple, even a child of seven or eight could do it.  You put the cuff on your arm, switch on, press a button and the machine does the rest.  There's no need to take your pulse; no need to listen with a stethoscope.  All you have to do is write down the result and keep a log.  The Blood Pressure Monitors normally come with Quick Start and detailed instructions and invariably give guidance as to what blood pressure you should expect to see.