Which component of blood pressure is represented by the first number in a reading?

The first number in a blood pressure reading represents the systolic pressure, which indicates the pressure in the arteries when the heart beats and pumps blood into them. It reflects the maximum pressure exerted on the arteries during heart contraction, making it a critical measurement for assessing cardiovascular health.

In contrast, diastolic pressure is the second number in the reading, which measures the pressure in the arteries when the heart is at rest between beats. Understanding the distinction between these two measurements is essential for accurately interpreting blood pressure readings and recognizing potential health issues. The pulse pressure, which is the difference between the systolic and diastolic pressures, and the mean arterial pressure, which represents the average pressure in a person's arteries during one cardiac cycle, are both derived from these values but do not represent the first number in the reading.