What is the typical extracellular concentration of hydrogen phosphate (HPO4--) in mEq/L?

The typical extracellular concentration of hydrogen phosphate (HPO4--) is around 4 mEq/L. This concentration is significant as hydrogen phosphate plays a critical role in various physiological processes, including energy metabolism and as a buffer in the blood. In the extracellular fluid, hydrogen phosphate exists mainly in equilibrium with dihydrogen phosphate (H2PO4-) and phosphate ions (PO4^3-), but among these, HPO4-- is a key player in maintaining the acid-base balance of the body.

The physiological range ensures that there is sufficient HPO4-- available to participate in biological reactions, particularly those involving ATP and cellular metabolism. This specific concentration can fluctuate slightly depending on various factors, including dietary intake and the body's metabolic state, but 4 mEq/L is a standard reference point in human physiology.

Other values listed do not accurately represent the typical extracellular concentration of hydrogen phosphate. For instance, much higher concentrations would pertain to different ions or compounds found in the extracellular fluid, while lower concentrations would not support the functions attributed to HPO4-- in physiological contexts. Thus, recognizing the specific concentration of HPO4-- is crucial for understanding its various roles in the body.