From VOA Learning English, this is the Health Report. The heart is our life force. It pumps blood, which carries Oxygen to every orgen in the body. As the blood flows through the blood vessels, it puts pressure on the vessel walls. That pressure is often measured when you go to see a doctor or other health care worker. Blood pressure readings are often taken with a cuff tightened around the upper arm. Blood pressure is measured using two numbers. The first, or upper number, is called the systolic pressure. The lower number is the diastolic pressure. The upper number shows. The pressure inside the blood vessels when the heart is pumping. The lower number shows the pressure when the heart rests between beats.