Systolic vs. Diastolic

Systolic and diastolic are two components of blood pressure.

Systolic is the rhythmic contraction of the heart in which blood is forced onward. This is the maximum pressure in the arteries. A normal range of systolic blood pressure for adults is 90-120 mmHg. In a blood pressure reading, it is the first or top number in the fraction.

Diastolic is the rhythmic expansion of the chambers of the heart during which they fill with blood. This is the minimum pressure in the arteries. A normal range of diastolic blood pressure for adults is 60-80 mmHg. In a blood pressure reading, it is the second or bottom number in the fraction.

A person's overall blood pressure is reported as a fraction in the form of systolic over diastolic. Both readings are measured in mmHg (millimeters of mercury). Blood pressure data is important in determining the overall health of the circulatory and cardiac systems.