What does blood pressure measure?

Blood pressure is a vital sign that measures the pressure exerted by circulating blood on the walls of blood vessels, particularly arteries, as the heart pumps it throughout the body. This pressure is a result of the force that blood exerts against the vessel walls during the cardiac cycle. Specifically, blood pressure readings typically consist of two numbers: systolic pressure, which occurs during heartbeats when the heart contracts and pumps blood, and diastolic pressure, which occurs when the heart is at rest between beats.

Understanding blood pressure is crucial in assessing cardiovascular health; abnormal levels can indicate various medical conditions, including hypertension or hypotension. The other options focus on different parameters related to blood but do not accurately define blood pressure itself. For example, volume refers to the total amount of blood, concentration of oxygen pertains to the oxygen content in the blood, and speed of blood flow is related to circulation dynamics rather than the pressure exerted by the blood.