No, K+ (Potassium) is not primarily extracellular.
Potassium (K+) is primarily an intracellular cation. The majority, about 98%, of the body's potassium is found inside cells. The concentration of K+ inside cells is high, ranging between 140-150 mmol/l. In contrast, only about 2% of the total potassium is found in the extracellular fluid, where its concentration is much lower, typically between 3.5 and 5 mmol/l.
| Location | K+ Concentration (mmol/l) | Percentage of Total K+ |
|---|---|---|
| Intracellular | 140-150 | 98% |
| Extracellular | 3.5-5 | 2% |
Therefore, while some K+ is present in the extracellular fluid, it is not the major location for this cation. This distribution is crucial for maintaining cell membrane potential and normal cellular function.
