In a blood pressure reading, which term refers to the bottom number?

• A. Systolic pressure
• B. Mean arterial pressure
• C. Pulse pressure
• D. Diastolic pressure

Answer: (D)

In a blood pressure reading, the bottom number represents the pressure in the arteries during the heart’s relaxation between beats. This diastolic pressure is the minimum arterial pressure in a typical cardiac cycle and reflects the baseline after the heart fills and before it contracts again. The top number is systolic pressure, the peak pressure when the heart contracts. The difference between the two is pulse pressure, while mean arterial pressure is an average pressure over the cycle, often estimated as diastolic pressure plus about one-third of the pulse pressure. For example, a reading of 120/80 mmHg has a diastolic (bottom) value of 80.