Final answer:
The top number in a blood pressure reading is the systolic pressure, indicating the maximum arterial pressure during a heartbeat, and the bottom number is the diastolic pressure, indicating the arterial pressure when the heart is resting between beats.
Step-by-step explanation:
When reading blood pressure (BP), the numbers represent two different types of pressure within the arteries. The top number is the systolic pressure, which indicates the maximum pressure in the arteries when the heart beats and pumps blood out. The bottom number is the diastolic pressure, which reflects the pressure in the arteries when the heart is at rest between beats. Generally, a healthy blood pressure range is considered to be a systolic pressure of less than 120 mm Hg and a diastolic pressure of less than 80 mm Hg. It is crucial to maintain blood pressure within a healthy range to reduce the risk of heart-related issues such as stroke or heart attack.