What key measurement is indicated by the top number in a blood pressure reading?

The top number in a blood pressure reading represents the pressure in the arteries when the heart beats, which is referred to as systolic blood pressure. This measurement is crucial because it reflects the force of blood against the artery walls during the contraction phase of the heart cycle, known as systole, when the heart pumps oxygenated blood into the bloodstream. Understanding this value is essential for assessing cardiovascular health and diagnosing potential hypertension or other heart-related issues.

The other options do not accurately describe the systolic reading. For example, the heart's resting pressure is actually represented by the bottom number, or diastolic blood pressure. The average pressure in the arteries and the pressure during blood flow might seem relevant but do not specifically define what the top number indicates in a standard blood pressure reading.