Final answer:
Most organs are held in place by tissue membranes, and specifically the peritoneum in the abdominal cavity.
Step-by-step explanation:
Most organs are held in place by thin transparent tissues called tissue membranes. Specifically, in the case of the digestive organs within the abdominal cavity, they are held in place by the peritoneum, which is a broad serous membranous sac made up of squamous epithelial tissue surrounded by connective tissue. The peritoneum itself is composed of two regions; the parietal peritoneum that lines the abdominal wall and the visceral peritoneum that envelops the abdominal organs. Between these two layers is the peritoneal cavity, which contains a small amount of fluid to minimize friction.