Veins are what kind of system?

• A. High pressure system
• B. Low pressure system
• C. Medium pressure system
• D. Variable pressure system

Answer: (B)

Veins are a low pressure system. They act as the body's reservoir, with walls that are thin and highly compliant, so a large amount of blood can be stored with only small increases in pressure. This contrasts with arteries, which must handle high pressures generated by the heart. Venous pressures at rest are quite low (central venous pressure is only a few mmHg), which is why return of blood to the heart relies on mechanisms like the skeletal muscle pump and respiratory movements to help propel blood forward. Valves prevent backflow, ensuring one-way flow toward the heart. So, the venous system is defined by its low pressure and high capacity to store blood, not by high or variable pressures.