Human fluid metabolism
Jump to navigation
Jump to search
At the most basic, the physiology of human fluid metabolism splits into the extracellular fluid compartment and the intracellular fluid compartment. Even with that separation, there is a constant exchange of water, ions, and non-ionized substances between the compartments and subcompartments. [1]
Electrolytes
In virtually all fluids, not just the concentration, but the ratios of four principal ions are critical:[2]
- Sodium (Na+) and potassium (K+)
- Chloride (Ca+2) and bicarbonate (HCO3+
Several other ions and molecules also are important, but sodium:potassium balance, for example, is fundamental to cell electrical activity.
| Substance | Extracellular volume | Intracellular volume |
|---|---|---|
| Sodium | 135-145 mEq/L | 10-20 mEq/L |
| Potassium | 3.5-5.0 mEq/L | 130-140 mEq/L |
| Chloride | 95-105 mEq/L | |
| Bicarbonate | 22-26 mEq/L | |
| Glucose | 90-120 mg/dL | |
| Calcium | 8.5-10 mg/dL | |
| Magnesium | 1.4-2.1 mg/dL | 20-30 mEqL |
| Urea nitrogen | 10-20 mg/dL | 10-20 mg/dL |
At this point in the diagram, we only distinguish between plasma and interstitial fluid, not urine, lymph, sweat, and other fluids within the extracellular compartment.
Blood versus fluid
References
- ↑ Arthur C. Guyton and John E. Hall, ed. (2000), Guyton and Hall Textbook of Medical Physiology, vol. Tenth Edition, W. B. Saunders, ISBN 072168677Xpp. 2-4
- ↑ Richard A. Preston (2002), Acid-Base, Fluids and Electrolytes Made Ridiculously Simple, McMaster, ISBN 0940780313, p. 5