She'll inflate the cuff to a pressure higher than your systolic blood pressure, and it will tighten around your arm. Then she'll release it. As the cuff deflates, the first sound she hears through the stethoscope is the systolic blood pressure. It sounds like a whooshing noise. The point where this noise goes away marks the diastolic blood pressure.
Blood pressure refers to the force exerted by circulating blood on the walls of blood vessels and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as blood moves through arteries, arterioles, capillaries, and veins; the term blood pressure generally refers to arterial pressure, i.e., the pressure in the larger arteries, arteries being the blood vessels which take blood away from the heart.
The guidelines also redefined the various categories of hypertension. It eliminated the category of prehypertension, which had been defined as systolic blood pressure of 120 to 139 mm Hg or diastolic pressure (the lower number in a reading) of 80 to 89 mm Hg. Instead, people with those readings are now categorized as having either elevated pressure (120 to 129 systolic and less than 80 diastolic) or Stage 1 hypertension (130 to 139 systolic or 80 to 89 diastolic).
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.