No, the heart is not covered with a mucous membrane. Instead, the heart is surrounded by a double-walled sac known as the pericardium. The pericardium consists of an outer fibrous layer and an inner serous layer. The serous layer produces a lubricating fluid that allows the heart to move smoothly during the heartbeat.
A mucous membrane, on the other hand, is a lining that secretes mucus and is typically found in areas such as the respiratory, gastrointestinal, and urogenital tracts. These membranes serve to protect and moisten the surfaces of organs that come into contact with outside elements or substances. Since the heart is a muscular organ that pumps blood and is located within the thoracic cavity, it does not have the same type of protective lining as those found in mucous membranes.