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The pressure created by blood pumping through the heart is present in all blood
vessels. The term "blood pressure" refers to the force exerted by
blood against the walls of the arteries.
There are actually two blood pressures — systolic (sis-tol'ik) and diastolic (di-astol'ik). Systolic blood
pressure is the force exerted by blood against the walls of the arteries during
the pumping phase of the cardiac cycle (systole). Diastolic blood pressure is
that force during the relaxation phase of the cardiac cycle (diastole). Blood
pressure is higher during systole when blood is being pumped forcefully out
of the heart and into the arteries. It is lower during diastole when the ventricles
of the heart are relaxed.
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