Mean arterial pressure is equal to diastolic pressure plus one-third of the pulse pressure. an equivalent equation is map = 2/3 dbp + 1/3 sbp. why is diastolic blood pressure (dbp) a larger component of map than systolic blood pressure (sbp) ?

This is because the ventricular diastole or the filling of the ventricles with blood takes much more time than ventricular systole or the pumping of blood from the ventricles to systemic and pulmonary circulations. The difference in time between diastole and systole reflects on the equation.