THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -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. This is called pericardial effusion.

Detailed explanation-2: -A pericardial effusion refers to the accumulation of excess fluid in the pericardial sac surrounding the heart. In a healthy individual, the pericardial sac contains between 15 and 50 milliliters (mL) of serous fluid.

Detailed explanation-3: -The pericardium is a membrane like a sac that surrounds the heart and its major blood vessels. Normally there is a small amount of fluid between the pericardium and the heart that helps cushion the heart and reduces friction between the heart and the pericardium when the heart beats.

Detailed explanation-4: -The pericardial cavity is the potential space formed between the two layers of serous pericardium around the heart. Normally, it contains a small amount of serous fluid that acts to reduce surface tension and lubricate. Therefore, the cavity facilitates the free movement of the heart.