Final answer:
The intracellular fluid (ICF) is consistent in volume as a percentage of body weight among infants, adult males, and adult females, accounting for about 60 percent of the total body water and remaining stable due to the regulation of cellular water content.
Step-by-step explanation:
The body fluid compartment that maintains a constant volume (percentage of body weight) across infants, adult males, and adult females is the intracellular fluid (ICF). The ICF is the fluid contained within cells, constituting about 60 percent of the total body water. Despite various factors, such as age, gender, and body composition, this percentage remains relatively stable. In adult males, the ICF accounts for approximately 25 liters of fluid.
The stability of ICF is crucial because fluctuations in cellular water content can lead to cell dysfunction or death. For example, if a cell's water content drops too low, this can result in the cytosol becoming hyper-concentrated with solutes, impairing normal cellular processes. Conversely, an excessive water intake may cause the cell to swell and potentially burst.
Women generally have a higher percentage of body fat compared to men, which corresponds to a slightly lower percentage of body water. However, this does not significantly alter the proportion of intracellular fluid. Therefore, despite differences in total body water content, the ratio of intracellular fluid compared to body weight remains consistent among infants, adult males, and adult females.