What is mean arterial pressure?

Mean arterial pressure (MAP) is defined as the average blood pressure throughout the cardiac cycle. It provides an important measure of the perfusion pressure experienced by the organs and tissues. Since the heart spends more time in diastole (the relaxation phase) than in systole (the contraction phase), MAP is not simply the arithmetic average of systolic and diastolic pressures. Instead, it can be calculated using the formula: MAP = diastolic pressure + 1/3(systolic pressure - diastolic pressure).

This calculation reflects the longer duration of diastole compared to systole and gives a more accurate representation of the effective blood pressure that drives blood flow to the organs. It is critical in assessing cardiovascular health and understanding how well blood is circulating to meet the metabolic demands of tissues.

The other definitions provided in the options do not capture this essential concept of averaged pressure throughout the entire cycle of the heartbeat, highlighting why the correct answer is focused on the average pressure during the entirety of the cardiac cycle rather than specific moments or measurements.