What is the function of pericardial fluid? Where is it found?

Pericardial fluid is a serous fluid secreted by the serous layer of the pericardium into the pericardial cavity. The pericardium itself has two layers:

• The fibrous pericardium – the tough outer layer attached to the diaphragm.
• The serous pericardium – further divided into the parietal layer and the visceral layer (which is in direct contact with the heart).

Pericardial fluid, produced mainly by ultrafiltration, surrounds the visceral layer. It acts as a lubricant, allowing smooth movement of the heart and reducing friction during pumping. Most of the fluid is drained by the lymphatic capillaries.

The fluid contains lactate dehydrogenase (LDH), proteins, and lymphocytes. It also helps protect the heart from infections that may spread from nearby organs such as the lungs. Normally, the pericardial cavity holds about 10–50 ml of this fluid.