Which term refers to the hydrostatic force that blood exerts against the wall of a vessel?

• A. Gum disease
• B. Sunscreen
• C. Blood pressure
• D. Helmet

Answer: (C)

Blood pressure is the hydrostatic force that blood exerts on the inner walls of blood vessels. It arises from the heart pumping blood and the resistance provided by the vessel walls and blood volume. When the heart contracts, pressure peaks (systolic pressure); between beats, pressure drops (diastolic pressure). These two values, measured in millimeters of mercury, are typically written as the systolic over diastolic number (for example, 120/80 mmHg). This force is what drives blood through the circulation to deliver oxygen and nutrients to tissues. If pressure is too high or too low, health risks can arise. The other terms listed don’t describe a force in blood vessels—gum disease is dental, sunscreen protects skin, and a helmet is safety gear.