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Physiology · Cardiovascular

Systolic, diastolic, mean and pulse pressure !

  • Measurement
  • Exam priority: high

Blood pressure has a top number when the heart pushes, a bottom number when it rests, and an average that keeps organs perfused.

Updated 2026-11-01

Also called: Blood pressure, Mean arterial pressure (MAP)

See it in 3D: Ascending aorta · Aortic arch · Brachial artery

What it is

Arterial pressure swings with each beat between systolic (peak) and diastolic (lowest) values. Pulse pressure is the difference and depends mostly on stroke volume and arterial stiffness. Mean arterial pressure is the time-averaged pressure that drives flow into organs.

Key facts

  • The pressure wave travels faster than the blood itself (≈ 3–15 m/s); it speeds up in stiff arteries.
  • Toward the periphery the systolic peak rises and the diastolic falls slightly (pulse amplification), but mean pressure falls only a little until the arterioles.
  • The aorta's elastic recoil (Windkessel effect) keeps flow going in diastole.
  • A cuff that is too small reads falsely high.

Cardiac cycle (Wiggers diagram)

Cardiac cycle (Wiggers diagram): Rapid ejection Pressure (mmHg)040801200–25 mmHg detail: atrium and ventricle01020LV volume (mL)50120ECGHeart sounds0200400600800Time (ms)AortaLVdicrotic notchacvLALVEDV 120ESV 50PQRSTS1S2AOACMCMO1234567

HR 75/minCycle 800 msSystole ≈ 300 msSV 70 mLEF 58%

3. Rapid ejection (≈ 220–330 ms)

Once LV pressure exceeds aortic diastolic pressure (about 80 mmHg) the aortic valve opens and most of the stroke volume leaves. LV and aortic pressures peak (about 120 mmHg).

  • Valves: aortic open, mitral closed
  • Sound: none normally (the aortic stenosis murmur is heard here)
  • ECG: ST segment
  • Aorta
  • Left ventricle (LV)
  • Left atrium (LA)
  • LV volume
  • ECG
  • S1 and S2
  • Ventricular systole
  • Ventricular diastole
  • Valve events (MC, AO, AC, MO)
Follow the aortic pressure trace: peak in ejection, the notch at aortic closure, the slow fall in diastole.

Equations

Pulse pressurePP = SBP − DBP
SBP
systolic pressure
DBP
diastolic pressure
Mean arterial pressure (estimate)MAP ≈ DBP + PP/3

At fast heart rates systole takes a larger share, and MAP moves closer to the arithmetic average.

Reference values (adult)

ParameterValueNote
Normal blood pressure< 120/80 mmHg
Mean arterial pressure≈ 70–100 mmHg≥ 65 mmHg is the usual target in shock
Pulse pressure≈ 30–50 mmHg
Hypertension (common thresholds)≥ 130/80 or ≥ 140/90 mmHgdepends on the guideline

Approximate values for a healthy adult at rest; each laboratory sets its own ranges.

Clinical notes

  • Aortic regurgitation: bounding pulses and a wide pulse pressure (high systolic, low diastolic).
  • Cardiac tamponade: narrow pulse pressure and pulsus paradoxus (systolic fall > 10 mmHg on inspiration).

Test yourself

Think of the answer, then tap the question to see it.

A patient's blood pressure is 150/60 mmHg. What are the pulse pressure and the estimated MAP?

Pulse pressure 90 mmHg; MAP ≈ 60 + 90/3 = 90 mmHg.

Why does an older person often have a high systolic but normal or low diastolic pressure?

A stiff aorta stores less blood in systole, so systolic pressure rises more, and recoils less in diastole, so diastolic pressure falls: wide pulse pressure.

Why is pulse pressure narrow in severe hypovolemia?

Stroke volume is small, and sympathetic vasoconstriction keeps diastolic pressure relatively maintained, so the difference between systolic and diastolic narrows.

Why is MAP not the simple average of systolic and diastolic pressure at rest?

At rest about two thirds of each cycle is diastole, so the time-averaged pressure sits closer to the diastolic value.

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See it in 3D

The structures of Durgical's 3D anatomy where it happens.

← All of physiology

Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given.

Sources: 20.2 Blood Flow, Blood Pressure, and Resistance (OpenStax (Rice University), 2022); Essential Hypertension (StatPearls (NCBI Bookshelf), 2025); Cardiac Tamponade (StatPearls (NCBI Bookshelf), 2025); Hall JE. Guyton and Hall Textbook of Medical Physiology, 13th ed. (ch. 15). Reference book used to check facts; its text and figures are not reproduced (Elsevier, 2016).

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Representative model, for educational purposes only.