High Blood Pressure: What Is Blood Pressure?
Blood pressure is the measure of the force
of your blood moving through your body's "circulatory system."
This complex network of veins and arteries contains blood
vessels that can be as large as a banana or so narrow that
blood cells can barely squeeze through them. Ideally, your
blood flows through almost 100,000 miles of arteries and veins
in a smooth stream -- much like water flowing through your
home's faucets into the sink or tub.
Within your body, the beats of your heart
create a pressure-driven force that sends your blood moving
through the body's arterial pathways in a steady, pulsating
rhythm. This "force" is measured to determine your blood
pressure level.
With each beat, your heart contracts,
sending out a "surge" of pressure into the bloodstream. This
surge period is called
"systolic" from a Greek word meaning "to contract."
After the pressure surge, your heart rests for a brief time and
"expands" to get ready for another beat. The arteries that have
received the surge of blood now rebound, forcing it further
through the system. This is called the
"diastolic" or "expansion"
period.
Doctors measure your blood pressure during
each of these periods. They often say "your pressure is 120
over 80," or some other combination of numbers. This first
number is a measure of the "systolic push" of the heartbeat on
the blood. The second number is the "diastolic" measurement of
the pressure in your arteries as blood continues to flow
through the system while the heart is at
rest.
Finding this measurement is easy. Anyone
can do it with a simple home monitoring device called a
sphygmomanometer or blood pressure cuff. Your doctor's
device may be a little more sophisticated -- with a cuff, a
stethoscope, and a pressure gauge -- but they all work pretty
much the same way. When your pressure is measured, this cuff is
tightened to cut off the circulation momentarily. The cuff is
loosened, and as the blood begins to flow again, the device
measures the systolic and diastolic forces. The measurement is
expressed in numbers as though they were a fraction (e.g.,
140/90).
Next:
What Do We
Mean by "You Have High Blood
Pressure"?
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