Blood pressure is a measurement of the pressure exerted by the circulating blood on the partitions of the arteries, veins and chambers of the heart. The pressure of blood is measured in the context of systolic and diastolic activities. If the arteries change into contracted, the passage of blood is hampered and it increases the pressure of blood. The situation causes high blood pressure or hypertension while low blood pressure is called hypotension. The condition may be characterized with the symptoms equivalent to extreme blood loss, infection, fluid loss or injury to the heart.