systemic arterial blood pressure is referred to as blood pressure (bp). blood pressure is the pressure that acts on the walls of blood vessels when blood flows in blood vessels. it is the driving force that drives blood to flow in blood vessels. the ventricles contract and blood flows from the ventricles into the arteries. at this time, the pressure of the blood on the arteries is the highest, which is called systolic blood pressure (sbp). the ventricles relax, the arteries retract elastically, and the blood slowly continues to flow forward, but the blood pressure drops. the pressure at this time is called diastolic blood pressure (dbp).