AAMC Chemical and Physical Foundations of Biological Systems (C/P) Full-Length (FL) 2 Practice Test 2026 - Free MCAT Practice Questions and Study Guide

The lower number in a blood pressure reading, such as 130/85, indicates diastolic pressure. This pressure reflects the force of blood against the artery walls when the heart is at rest between beats, specifically during the phase of the cardiac cycle known as diastole. During this phase, the heart fills with blood, and the pressure in the arteries drops.

In this example, 85 is the diastolic pressure, which is critical for assessing cardiovascular health. It helps determine how well the body maintains blood flow to organs and tissues when the heart is not actively pumping. Understanding diastolic pressure is vital because it can indicate potential risks for conditions such as hypertension if readings are consistently elevated.

The other terms in the answer choices do not fit this context: systolic pressure, which is the upper number, measures pressure during heartbeats; mean arterial pressure gives an average blood pressure throughout the cardiac cycle; and pulse pressure is the difference between systolic and diastolic pressures.