The pressure levels in your circulatory system change as your heart contracts and relaxes. Its highest pressure occurs during the systolic phase of the cardiac cycle (contraction). The sphygmomanometer, more commonly known as a blood pressure cuff, is used to measure blood pressure. It consists of an inflatable cuff that wraps around your upper arm, a bulb attached to a tube to pump the cuff full of air and a gauge that shows the level of pressure in your arteries as your heart contracts and relaxes.

The cuff is wrapped around your arm and inflated to stop the blood flow in the main artery. As the cuff is slowly allowed to deflate, blood flows through the artery again. A stethoscope is used to listen to your blood flow as the cuff deflates. The first sound heard from the blood vessel is the systolic pressure. The cuff continues to deflate until no further sounds are heard a point called the diastolic pressure. The systolic pressure over the diastolic pressure constitute the blood pressure reading. Normal blood pressure ranges from 90/60 to 140/80.