The brain requires unobstructed blood flow to nourish its many functions. Very high, sustained blood pressure will eventually cause blood vessels to weaken. Over time these weaken vessels can break, and blood will leak into the brain. The area of the brain that is being fed by these broken vessels start to die, and this will cause a stroke. Additionally, if a blot clot blocks a narrowed artery, blood ceases to flow and a stroke will occur.
Healthcare professionals use a stethoscope and a manual sphygmomanometer to measure your blood pressure. Typically they take the reading above your elbow. The sphygmomanometer has a bladder, cuff, bulb, and a gauge. When the bulb is pumped it inflates the bladder inside the cuff, which is wrapped around your arm. This inflation will stop the blood flow in your arteries. The stethoscope is used to listen for sound of the heartbeat, and no sound indicates that there is no flow. As the pressure is released from the bladder, you will hear the sound of the blood flowing again. That point becomes systolic reading. The diastolic reading is when you hear no sound again, which means that the blood flow is back to normal.
When your heart contracts and squeezes blood out into your network of arteries, the pressure inside those blood vessels is at its highest. This is called systolic pressure and it’s the top number on your blood pressure reading. In between beats, the heart relaxes and the pressure drops. This is your diastolic blood pressure, and it’s the reading’s bottom number.
Typically, more attention is given to systolic blood pressure (the first number) as a major risk factor for cardiovascular disease for people over 50. In most people, systolic blood pressure rises steadily with age due to the increasing stiffness of large arteries, long-term buildup of plaque and an increased incidence of cardiac and vascular disease.