Review of Medical Physiology - William F. Ganong 2002

Formation and Excretion of Urine
Regulation of Composition and Volume of Extracellular Fluid
Regulation of Specific Ionic Composition

The levels of certain specific ions in ECF, as well as glucose and other non-ionized compounds essential for METABOLISM, are maintained through specific regulatory mechanisms (Chapter 17). The concentration of Ca2+ ions in ECF is regulated via a feedback mechanism between the Ca2+ level and the secretion of Parathyroid glands and Calcitonin-secreting Cells (see Chapter 21). The concentration of Mg2+ is also tightly regulated, although the mechanisms governing Mg2+ metabolism are not yet fully understood.

The mechanisms determining the content of Na+ and K+ are an integral part of the aforementioned systems that regulate ECF volume. The concentration of these ions also depends on the H+ concentration, and pH is one of the primary Factors influencing the anionic composition of ECF.



Last update: 10/08/2026

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