Blood pressure provides clues about the amount of work your heart is doing to pump blood through your arteries. It’s one of your body’s four major vital signs. The other vital signs are:
Vital signs help show how well your body is functioning. If a vital sign is too high or too low, it’s a sign that something may be wrong with your health.
Blood pressure is measured using two different readings. The first reading is called your systolic pressure. That’s the first or top number in a reading. The second reading is your diastolic number. That one is the second or bottom number.
For example, you may see blood pressure written as 117/80 mm Hg (millimeters of mercury). In that case, the systolic pressure is 117 and the diastolic pressure is 80.
Systolic pressure measures the pressure inside of the artery when the heart is contracting to pump blood. The diastolic pressure is the pressure inside the artery once the heart is resting between beats.
Higher numbers in either recording can show that the heart is working extra hard to pump blood through your arteries. This may be the result of an outside force, like if you’re stressed or scared, which causes your blood vessels to become more narrow. It could also be caused by an internal force, such as buildup in your arteries that can cause your blood vessels to become narrower.
If you’d like to check your own blood pressure at home, it’s best to first check with your doctor about how they’d like you to monitor and record it. For example, your doctor may prefer you to check your blood pressure:
before or after a certain medication
at certain times of the day
when you’re stressed or feeling dizzy