Which side of the heart is the low-pressure side?

• A. Systemic circulation
• B. Left side
• C. No pressure
• D. Right side

Answer: (D)

The right side is the low-pressure side because it pumps blood into the pulmonary circulation, which has far lower resistance than the systemic circuit. The right atrium and right ventricle operate at much lower pressures than the left atrium and left ventricle, which must generate high pressure to push blood through the entire body. In practical terms, pulmonary pressures are relatively low, while systemic pressures are high (for example, systemic arteries run around 100–120 mmHg systolic). The left side handles the high-pressure systemic circulation, and the notion of “no pressure” isn’t physiologically correct since some pressure is always generated to move blood.