What is Blood Pressure?
Blood pressure is the force blood exerts against artery walls as the heart pumps it around the body. It's recorded as two numbers — systolic (during a heartbeat) over diastolic (between beats) — measured in millimeters of mercury (mmHg). Consistently high blood pressure (hypertension) damages arteries and raises the risk of heart attack and stroke.
Blood pressure is the pressure of circulating blood on artery walls, expressed as systolic/diastolic in mmHg — a normal reading is around 120/80 mmHg.
Try it: interactive calculator
Step-by-step worked examples
A person has a blood pressure of 120/80 mmHg. Find their mean arterial pressure (MAP).
MAP = DBP + (SBP − DBP)/3 = 80 + (120 − 80)/3 = 80 + 13.3 = 93.3 mmHg
A patient's blood pressure is 140/90 mmHg. Calculate the MAP.
MAP = 90 + (140 − 90)/3 = 90 + 16.7 = 106.7 mmHg
A person's blood pressure is 100/60 mmHg. What is their MAP?
MAP = 60 + (100 − 60)/3 = 60 + 13.3 = 73.3 mmHg
Flashcards
Quick quiz
Q1.A reading of 120/80 mmHg — what does 80 represent?
Q2.Calculate MAP for a blood pressure of 130/85 mmHg.
Q3.Which blood pressure category is 135/85 mmHg?
Q4.What is pulse pressure?
The full card deck, worked steps and AI-tutor support for “What is Blood Pressure?” are in Notek — study by hand before your exam.
Common mistakes
Only the top (systolic) number matters. — Correct: Both numbers matter — isolated diastolic or systolic elevation both carry cardiovascular risk.
Blood pressure is the same all day. — Correct: It naturally fluctuates with activity, stress, sleep, and time of day — one reading isn't the full picture.
MAP is just the average of systolic and diastolic. — Correct: MAP weights diastolic more heavily because the heart spends more time in diastole: MAP = DBP + (SBP−DBP)/3.
High blood pressure always causes noticeable symptoms. — Correct: Hypertension is often called a 'silent' condition — many people feel fine despite dangerously high readings.
FAQ
What is blood pressure?
It's the force blood exerts on artery walls, recorded as systolic over diastolic pressure in mmHg.
What is the formula for mean arterial pressure?
MAP = DBP + (SBP − DBP) / 3, where SBP is systolic and DBP is diastolic pressure.
What are examples of blood pressure readings?
120/80 mmHg (normal), 135/85 mmHg (elevated/stage 1), and 150/95 mmHg (stage 2 hypertension) are common examples.
How do you calculate blood pressure (MAP)?
Add the diastolic pressure to one-third of the difference between systolic and diastolic — try it in the calculator above.