What is the correct distinction between systolic and diastolic blood pressure readings?

• A. Systolic pressure occurs during heart contraction; diastolic during resting phase between beats.
• B. Systolic pressure during resting phase; diastolic during contraction.
• C. Systolic and diastolic are the same measurement.
• D. Systolic is measured in arteries; diastolic in veins.

Answer: (A)

The difference comes from the two phases of the heartbeat: contraction and relaxation. Systolic pressure is the peak arterial pressure that occurs when the heart contracts and pushes blood into the arteries. Diastolic pressure is the lowest arterial pressure that occurs when the heart relaxes between beats, allowing the ventricles to fill. When you hear or see a blood pressure reading, the higher value is systolic and the lower value is diastolic (for example, in a typical reading of 120/80 mmHg, 120 is systolic and 80 is diastolic). This distinction matters because systolic pressure reflects the force the heart generates with each beat, while diastolic pressure reflects the baseline arterial pressure when the heart is at rest. The other statements don’t fit because systolic isn’t during relaxation, diastolic isn’t during contraction, they are not the same measurement, and both pressures are measured in arteries (not veins).