Where is most of the potassium in a healthy person located?

Most of the potassium in a healthy person is located inside the cells. This is primarily due to the role of potassium as a key intracellular ion, essential for various cellular functions, including maintaining the resting membrane potential of cells, facilitating muscle contractions, and participating in enzymatic processes.

Potassium is predominantly found in the intracellular fluid, with around 98% of the body's potassium located within cells. This distribution is vital for cellular homeostasis and communication. The Na+/K+ ATPase pump plays a significant role in maintaining this balance by actively transporting sodium out of the cell and potassium into the cell, creating an electrochemical gradient essential for normal physiological functions.

In contrast, only a small fraction of potassium exists in the bloodstream or extracellular fluid, which is crucial for regulating overall body functions but represents a minor proportion of total body potassium. The extracellular fluid has a much lower concentration of potassium compared to the intracellular space, highlighting the importance of the intracellular compartment in potassium storage and function.