In a blood pressure reading, what is the top number called?

The top number in a blood pressure reading is referred to as systole. This number represents the pressure in the arteries when the heart contracts and pumps blood out into the body. It is a crucial measure because it indicates how hard the heart is working to circulate blood and conveys the maximum arterial pressure during each heartbeat.

Understanding this term is essential for interpreting blood pressure readings accurately. Systolic pressure is typically the higher of the two values recorded in a blood pressure measurement, with the bottom number, known as diastolic pressure, representing the pressure when the heart is at rest between beats.

The other terms listed do not apply to the measurement context in the same way: diastole refers to the resting period of the heart cycle, hypertension signifies a condition of consistently high blood pressure, and homeostasis pertains to the body's ability to maintain stable internal conditions. Thus, systole is the precise term for the top number in blood pressure readings, highlighting its role in monitoring cardiovascular health.