Question

Friction between membranes of the heart is reduced by:
a. serous fluid in the pericardial cavity
b. the epicardium.
c. a blood-filled sinus called the pericardium.
d. a cushion of air that surrounds the heart.
e. fluid between the epicardium and the myocardium

Answer 1

Answer:

The correct option is : a. serous fluid in the pericardial cavity

Explanation:

The heart is enclosed in a sac containing the heart, known as the  pericardium. The pericardium has two layers- fibrous and serous layer.

The serous layer of the pericardium produces and secretes the pericardial fluid into the pericardial cavity.

The pericardial fluid is a lubricating serous fluid present in the pericardial cavity. It reduces the friction caused between the pericardial membranes by lubricating the epicardial surface.