Blood pressure simply describes the pressure of blood on the vessel walls in
which it is contained. The term blood pressure as commonly used refers
to systemic arterial pressure. Systolic blood pressure (SBP) is the highest pressure in the arterial system during cardiac contraction, i.e. during systole. Diastolic blood pressure (DBP)
is the lowest pressure occurring in the systemic arteries during a cardiac cycle
and occurs during diastole. Sixty percent of mean arterial pressure is determined
by diastolic and 40% by systolic pressure. This is because arterial BP remains
closer to the diastolic pressure than the systolic for more of the cardiac cycle.