Which statement best describes the function of pericardial fluid?

• A. It nourishes cardiac tissue
• B. It increases friction to stabilize the heart
• C. It reduces friction during heart contractions
• D. It compresses the heart to regulate it

Answer: (C)

Pericardial fluid acts as a lubricant in the pericardial cavity, allowing the heart to move smoothly within the sac as it beats. This small amount of serous fluid reduces friction between the heart’s surface and the pericardium during every contraction and relaxation, supporting efficient, friction-free movement. Nourishment of cardiac tissue comes from the coronary blood supply, not from this fluid. The fluid isn’t intended to increase friction or to compress the heart to regulate its function; in fact, excess fluid can impair filling and circulation, which is a problem, but normal function is lubrication.