The force of blood on artery walls is called blood pressure. Normal pressure is important for the proper flow of blood from the heart to the body's organs and tissues. Each heart beat forces blood to the rest of the body. Near the heart, pressure is higher, and away from it lower.
Blood pressure depends on many things, including how much blood the heart is pumping and the diameter of the arteries the blood is moving through. Generally, the more blood that's pumped and the narrower the artery the higher the pressure is. Blood pressure is measured both as the heart contracts, which is called systole, and as it relaxes, which is called diastole. Systolic blood pressure is measured when the heart ventricles contract. Diastolic blood pressure is measured when the heart ventricles relax.
A systolic pressure of 115 millimeters of mercury is considered normal, as is a diastolic pressure of 70. Commonly, this pressure would be stated as 115 over 70.Stressful situations can temporarily cause blood pressure to rise. If a person has a consistent blood pressure reading of 140 over 90, he would be evaluated for high blood pressure.
Left untreated, high blood pressure can damage important organs, such as the brain and kidneys, as well as lead to a stroke.
Review Date 9/7/2021
Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.