THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -The two layers of serous pericardium : visceral and parietal are separated by the pericardial cavity, which contains 20 to 60 mL of the plasma ultrafiltrate. The pericardium acts as mechanical protection for the heart and big vessels, and a lubrication to reduce friction between the heart and the surrounding structures.

Detailed explanation-2: -The inner (visceral) layer of the serous pericardium lines the outer surface of the heart itself. Between the two layers of the serous pericardium is the pericardial cavity, which contains pericardial fluid. It is this fluid that provides lubrication between the two layers, and allows the heart to expand and contract.

Detailed explanation-3: -Pericardial fluid helps reduce friction between the epicardial membranes of the heart, thereby helping the membranes to glide over each other during each heartbeat. It is found in the pericardial cavity (where it is secreted by the serous layer of the pericardium).

Detailed explanation-4: -A fibrous sac known as the pericardium surrounds the heart. This sac is made of two thin layers with a small amount of fluid between them. This fluid reduces friction between the layers as they rub against each other when the heart beats. In some cases, too much fluid builds up between these two layers.