Transcellular fluid is one of the compartments of total body water.

• A. It is not a TBW compartment
• B. It is one of the TBW compartments
• C. It is the only TBW compartment
• D. It contains more TBW than extracellular

Answer: (B)

Transcellular fluid is a defined part of the total body water. Total body water is made up of intracellular fluid inside cells and extracellular fluid outside cells. The extracellular fluid isn’t one homogeneous space; it’s divided into interstitial fluid, plasma, and transcellular fluid. Transcellular fluid includes cerebrospinal fluid, synovial fluid, pleural and pericardial fluids, peritoneal fluid, biliary and pancreatic secretions, and other body fluids that are contained within epithelial-lined compartments. Although this fluid volume is relatively small compared with the other extracellular compartments, it is still part of the total body water. So, it is indeed one of the compartments that comprise TBW.