Blood pressure is the a measure of the amount of force exerted by the pump of the heart on the walls of the blood vessels.
When the heart pumps this pressure is at its greatest – this is known as systolic pressure. When the heart relaxes the pressure is at its lowest – this is diastolic pressure.
Along with heart rate, blood pressure tends to rise when the body has a temporary need for greater nutrients, for example when we exercise or are in danger. This is only a problem if we suffer physical stress of this type for extended periods, meaning that the blood pressure remains relatively high (Hypertension).
High blood pressure can result from either an increase in the amount of blood being pumped (i.e. a faster, more forceful heart beat), an increase in the tension of the artery walls or a combination of the two.
According to current thinking, for adults the ideal systolic blood pressure should be between 90 - 120mmHg with diastolic between 60 – 80mmHg. However, don't forget in reality blood pressure varies enormously according to activity, posture, time of day, and emotional sate.