What does blood pressure measure?

Blood pressure specifically measures the force of blood against the walls of the blood vessels, typically expressed in millimeters of mercury (mmHg). This measurement is crucial because it provides vital information about a person's cardiovascular health. When the heart pumps, it creates pressure in the arteries that can be categorized into two readings: systolic pressure, which occurs when the heart contracts, and diastolic pressure, when the heart is at rest between beats.

Understanding blood pressure is essential for assessing overall heart health and can indicate various conditions such as hypertension or hypotension. The other options, while related to various aspects of cardiovascular health, do not accurately define what blood pressure measures. For instance, while the strength of the heart muscle can influence blood pressure, it is not the direct measure of blood pressure itself. Similarly, the amount of oxygen in the blood pertains to oxygenation rather than pressure, and the volume of blood in circulation relates to overall blood volume rather than the specific pressure against blood vessel walls.