For a typical 70 kg adult, distribution of total body water into plasma, extracellular fluid, and intracellular fluid is:

For a typical 70 kg adult, distribution of total body water into plasma, extracellular fluid, and intracellular fluid is:

• A. 3 L plasma, 12 L ECF, 27 L ICF
• B. 4 L plasma, 16 L ECF, 22 L ICF
• C. 5 L plasma, 15 L ECF, 22 L ICF
• D. 3 L plasma, 16 L ECF, 23 L ICF

Answer: (D)

The idea being tested is how total body water is partitioned among body compartments in a typical adult. In a 70 kg person, total body water is about 42 liters. Most of that water is inside cells (intracellular fluid), roughly two-thirds, around 28 liters, while the extracellular fluid makes up about one-third, about 14 liters. The extracellular fluid itself is divided into plasma (about 3 liters) and interstitial fluid (roughly 11 liters). These values can vary a bit, but they stay in these general ranges. So the option that fits these proportions best is one that has plasma around 3 liters, extracellular fluid close to 16 liters, and intracellular fluid around 23 liters, totaling about 42 liters. This arrangement keeps intracellular fluid as the largest compartment, plasma as a small portion of the extracellular fluid, and the extracellular fluid value in a plausible range. The other choices deviate more from these typical relationships—for example, by giving too little or too much extracellular fluid or by misplacing the relative sizes of the compartments—making them less representative of the usual distribution.

The idea being tested is how total body water is partitioned among body compartments in a typical adult. In a 70 kg person, total body water is about 42 liters. Most of that water is inside cells (intracellular fluid), roughly two-thirds, around 28 liters, while the extracellular fluid makes up about one-third, about 14 liters. The extracellular fluid itself is divided into plasma (about 3 liters) and interstitial fluid (roughly 11 liters). These values can vary a bit, but they stay in these general ranges.

So the option that fits these proportions best is one that has plasma around 3 liters, extracellular fluid close to 16 liters, and intracellular fluid around 23 liters, totaling about 42 liters. This arrangement keeps intracellular fluid as the largest compartment, plasma as a small portion of the extracellular fluid, and the extracellular fluid value in a plausible range. The other choices deviate more from these typical relationships—for example, by giving too little or too much extracellular fluid or by misplacing the relative sizes of the compartments—making them less representative of the usual distribution.