Normal blood pressure is important for proper blood flow to the body’s organs and tissues. The force of the blood on the walls of the arteries is called blood pressure. Blood pressure is measured both as the heart contracts, which is called systole, and as it relaxes, which is called diastole. Normal blood pressure is considered to be a systolic blood pressure of 115 millimeters of mercury a diastolic pressure of 70 millimeters of mercury (stated as "115 over 70"). If an individual were to have a consistent blood pressure reading of 140 over 90, he would be evaluated for having high blood pressure. If left untreated, high blood pressure can damage important organs, such as the brain and kidneys, as well as lead to a stroke.