The Meaning of Blood Pressure Numbers

Blood pressure is a measurement of the force exerted by blood against the walls of the arteries as the heart pumps blood throughout the body. Blood pressure is expressed as two numbers: systolic pressure over diastolic pressure. Systolic pressure is the pressure in the arteries when the heart beats, while diastolic pressure is the pressure in the arteries when the heart is at rest between beats.

A normal blood pressure reading is typically around 120/80 mmHg (millimeters of mercury). The systolic pressure is the first number and the diastolic pressure is the second number. A reading of 140/90 mmHg or higher is considered high blood pressure, also known as hypertension. However, blood pressure readings can vary throughout the day, and a single high reading does not necessarily indicate hypertension.