Which statement best defines diastolic pressure?

• A. Pressure during ventricular contraction
• B. Pressure in arteries when the heart relaxes
• C. Average arterial pressure over the cardiac cycle
• D. Pressure during systole

Answer: (B)

Diastolic pressure is the arterial pressure during the heart's relaxation phase. When the ventricles finish pumping, the heart relaxes (diastole) and the arterial walls rebound, so the pressure falls to a lower, minimum value in the arteries. This is the diastolic pressure—the lowest pressure in the arterial system during the cardiac cycle. In a typical reading like 120/80 mmHg, the diastolic number (80) reflects this relaxation period and is important because coronary arteries receive blood flow primarily during diastole.

The other part of the cycle, systolic pressure, is the pressure during ventricular contraction when the heart is actively pumping blood into the arteries. Average arterial pressure over the cycle is represented by mean arterial pressure, which combines both values but isn’t the same as diastolic pressure.