What is the peritoneum?

The peritoneum is a significant membrane in the body that serves a crucial role in the abdominal cavity. It is a serous membrane that lines the abdominal wall and covers the abdominal organs, providing a protective layer as well as allowing for smooth movement of the organs during digestion and other bodily processes. This characteristic is essential as it not only supports and protects the organs but also facilitates the functioning of the gastrointestinal system by reducing friction.

In contrast, the other options refer to different membranes or tissues that are associated with other organs and cavities in the body. The tissue surrounding the heart is known as the pericardium; the tissue lining the lungs is referred to as the pleura; and the tissue surrounding the brain is called the meninges. These structures each play vital roles specific to their locations, but they are not related to the peritoneum, which is explicitly involved in the abdominal region.