The largest portion of total body water is found in which tissue?

The largest portion of total body water is found in which tissue?

• A. Intracellular fluid
• B. Extracellular fluid
• C. Intravascular extracellular fluid
• D. Interstitial fluid

Answer: (A)

Water inside cells is the largest portion of total body water. In an average adult, total body water is about 60% of body weight, and roughly two-thirds of that resides as intracellular fluid inside cells (about 40% of body weight), while extracellular fluid outside cells accounts for about one-third (roughly 20% of body weight). The extracellular space itself splits into interstitial fluid and intravascular (plasma) fluid, with interstitial fluid being the larger part of the extracellular pool but still much smaller than the intracellular pool. The reason intracellular fluid dominates is that cells contain large amounts of water in the cytosol, maintained by osmotic gradients created by intracellular solutes; water readily distributes across membranes but the cell’s solute content keeps most of the water inside.

Water inside cells is the largest portion of total body water. In an average adult, total body water is about 60% of body weight, and roughly two-thirds of that resides as intracellular fluid inside cells (about 40% of body weight), while extracellular fluid outside cells accounts for about one-third (roughly 20% of body weight). The extracellular space itself splits into interstitial fluid and intravascular (plasma) fluid, with interstitial fluid being the larger part of the extracellular pool but still much smaller than the intracellular pool. The reason intracellular fluid dominates is that cells contain large amounts of water in the cytosol, maintained by osmotic gradients created by intracellular solutes; water readily distributes across membranes but the cell’s solute content keeps most of the water inside.