What are the names of upper and lower blood pressure readings?

The two numbers in a blood pressure reading represent the systolic blood pressure (top number) and the diastolic blood pressure (bottom number).

Systolic blood pressure is the pressure in your arteries when your heart beats. It is the highest pressure your arteries experience during one heartbeat.

Diastolic blood pressure is the pressure in your arteries when your heart rests between beats. It is the lowest pressure your arteries experience during one heartbeat.