Blood pressure is essentially the pressure exerted by the blood on the walls of the arteries while flowing through them. One type of pressure is the pressure exerted when blood is pumped into the circulatory system by the heart, and the other is due to the resistance offered by the arteries to it. In normal situations, the arteries are extremely elastic and expand or contract depending on the situation.

The blood pressure can change from minute to minute, as it increases when the heart pumps blood and falls when the heart relaxes. It also changes with changes in posture, exercise or while a person is sleeping. But, it should normally be less than 140/90 mm Hg for an adult. Blood pressure that stays above this level consistently is considered high. Your doctor may take several readings over a period before making a judgment about whether your blood pressure is considered to be in a high level range.

Blood pressure numbers indicate

• The higher (systolic) number represents the pressure while the heart is beating.
• The lower (diastolic) number represents the pressure when the heart is resting between beats.

The systolic pressure is always stated first and the diastolic pressure second. For example: 122/76 (122 over 76), systolic=122 mm of Hg, diastolic=76 mm of Hg.

Blood pressure of less than 140 over 90 is considered a normal reading for adults. A systolic pressure of 130 to 139 or a diastolic pressure of 85 to 89 needs to be watched carefully. A blood pressure reading equal to or greater than 140 (systolic) over 90 (diastolic) is considered elevated (high).

High Blood Pressure
Optimal or ideal blood pressure is less than 120/80. Normal blood pressure is considered to be less than 130/85 mm of Hg. High–normal is considered to be between 130–139/85–89 mm of Hg.

High blood pressure or hypertension, is divided into three stages
Stage 1: 140–159/90–99 mm of Hg.
Stage 2: 160–179/100–109 mm of Hg.
Stage 3: Greater or equal to 180/110 mm of Hg.