Blood pressure

Blood pressure
Medical diagnostics
A healthcare worker measuring blood pressure using sphygmomanometer.
MeSH	D001795
MedlinePlus	007490
LOINC	35094-2

Blood pressure is a measurement used in medicine. In the body, the arteries carry blood away from the heart. As blood travels through the arteries, it presses against the walls of the arteries. Blood pressure measures how hard the blood is pushing against the walls of the arteries.^[1]

Usually, "blood pressure" measures the pressure in larger arteries delivering blood to body parts other than the lungs, like the brachial artery in the arm. Blood pressure is usually measured in millimeters of mercury (mmHg).

There are two numbers in a blood pressure. The first is the systolic pressure. It measures how hard the blood pushes against the walls of the arteries when the heart is in systole (beating and pushing out blood). This is when the pressure against the walls of the arteries is highest. The second number is the diastolic blood pressure. It measures how hard the blood pushes against the walls of the arteries when the heart is in diastole (resting between beats and not pushing out any blood). For example, in the picture on this page, the pressure on the walls of the arteries is 122 mmHg when the heart is beating, and 65 mmHg when the heart is resting. This blood pressure would be written as "122/65" and read as "122 over 65."

Mean arterial pressure is a person's average blood pressure. Pulse pressure is the difference between the systolic and diastolic pressures.^[1]

To measure blood pressure, doctors use a device called a sphygmomanometer.

1. ↑ ^{1.0 1.1} "Understanding Blood Pressure Readings". American Heart Association. 2014-08-04. Retrieved 2015-01-03.