First 165 words of the document:
Blood pressure is the pressure of the blood against the walls of the arteries.
Blood pressure results from two forces. One is created by the heart as it pumps blood into the
arteries and through the circulatory system. The other is the force of the arteries as they resist
the blood flow.
What do blood pressure numbers indicate?
The higher (systolic) number represents the pressure while the heart contracts to pump
blood to the body.
The lower (diastolic) number represents the pressure when the heart relaxes between
The systolic pressure is always stated first. For example: 118/76 (118 over 76) systolic = 118,
diastolic = 76.
Blood pressure below 120 over 80 mmHg (millimetres of mercury) is considered optimal for
adults. A systolic pressure of 120 to 139 mmHg or a diastolic pressure of 80 to 89 mmHg is
considered "prehypertension" and needs to be watched carefully. A blood pressure reading of
140 over 90 or higher is considered elevated (high).