54. Blood Pressure and How We Measure It

The simple idea

• Systolic pressure — the peak during ejection (about 120 mmHg).
• Diastolic pressure — the lowest point between beats (about 80 mmHg).
• Pulse pressure = systolic − diastolic (about 40 mmHg) — rises with bigger stroke volume or stiffer arteries.
• Mean arterial pressure (MAP) — the average pressure driving blood to organs: about diastolic + one‑third of pulse pressure (≈ 93 mmHg).