Final answer:
Mean arterial pressure (MAP) is approximated by adding one-third of the pulse pressure to the diastolic pressure, giving an estimate of the average force driving blood into vessels.
Step-by-step explanation:
Mean arterial pressure (MAP) is approximated by adding one-third of the pulse pressure to the diastolic pressure. Pulse pressure is defined as the difference between systolic and diastolic pressures, which represent the maximal and minimal pressures in the arteries during the cardiac cycle, respectively.
To calculate the MAP, one would take the systolic pressure (the higher number in a blood pressure reading) and subtract the diastolic pressure (the lower number). This gives us the pulse pressure.
Then, one third of this value is added to the diastolic pressure to estimate MAP. For example, with a blood pressure reading of 120/80 mm Hg, the pulse pressure would be 120 - 80 = 40 mm Hg. One third of this pulse pressure is approximately 13.33 mm Hg. Adding this to the diastolic pressure gives us a MAP of 80 + 13.33, which is approximately 93.33 mm Hg.