Final answer:
Peritonitis involves an abnormal shift of fluid from the bloodstream into body tissue, caused by inflammation of the peritoneum due to various factors like bacterial infections or ruptured ulcers.
Step-by-step explanation:
Peritonitis, with associated fluid loss, is the result of an abnormal shift of fluid from bloodstream into body tissue. This condition occurs when the peritoneum, the lining of the abdominal cavity, becomes inflamed. Causes include ruptured ulcers, traumatic injury, or bacterial infections that breach the alimentary canal wall, thus allowing materials to spill into the peritoneal cavity and inducing inflammation. This leakage and accumulation of fluids in tissues characterize the abnormal fluid dynamics associated with peritonitis.