A “Sphyg” as doctors often call it is used to measure your blood pressure. It is a cuff that goes round your arm and is inflated until it stops the blood flowing. Then the pressure is let down until first the systolic beat is strong enough to let the blood through (the doctor listens with a stethoscope) and then the diastolic beat. That gives your blood pressure as two figures – 80/100 is typical of a healthy pressure I think. The systolic is the large one. The “lub-dup” noice your heart makes are teh two parts to the beat. the first is the diastolic – sending blood from your heart to the lung and the second the systolic – sending the blood round your body.