What is blood pressure?

• A. The force exerted by the blood against the blood vessel wall
• B. The speed of blood flow through arteries
• C. The amount of blood pumped per heartbeat
• D. The pressure of blood in the heart chambers

Answer: (A)

Blood pressure is the force that circulating blood exerts against the walls of blood vessels, especially arteries, as it flows through the circulatory system. This force comes from the heart pumping blood into the arteries and the resistance offered by the vessels. It changes with each heartbeat: higher when the heart contracts (systolic) and lower when the heart relaxes (diastolic), and we usually express it as a systolic over diastolic value (for example, 120/80 mmHg). The other statements describe different ideas—how fast blood moves, how much blood is ejected per beat, or the pressure inside the heart chambers—not the overall pressure exerted on vessel walls.