What does blood pressure measure?

Blood pressure specifically measures the force exerted by circulating blood on the walls of blood vessels, particularly arteries. This force is generated by the heart as it pumps blood throughout the body. Understanding blood pressure is crucial for assessing cardiovascular health since higher or lower than normal blood pressure can indicate various health issues. It consists of two measurements: systolic pressure, which occurs when the heart beats and pumps blood, and diastolic pressure, which occurs when the heart is at rest between beats. This measurement is commonly represented in millimeters of mercury (mmHg) and is a key vital sign monitored in both clinical settings and personal fitness assessments.

The other choices relate to different concepts: the amount of oxygen in the blood (involves oxygen saturation levels), the resistance of blood vessels during exercise (more related to how blood vessels constrict or dilate under physical stress), and the volume of blood in circulation (which pertains to overall blood volume rather than the pressure it exerts). Understanding these distinctions can enhance the comprehension of cardiovascular dynamics and overall health assessments.