Human fluid metabolism

## Contents

* 1 Electrolytes
* 2 Blood versus fluid
* 3 References

| Main Article
| Discussion
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This editable Main Article is under development and subject to a disclaimer.

[edit intro]

Basic compartments

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[edit]

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

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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[edit]

Again as a basic idea, blood is plasma that carries blood cells and additional circulating chemicals. Many clinical measurements involving blood chemistry are made on the easier-to-collect blood serum, which is the fluid remaining after blood clots. Serum does not circulate in the body, although it can accumulate near blood clots.

## References[edit]

1. ↑ 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
2. ↑ Richard A. Preston (2002), Acid-Base, Fluids and Electrolytes Made Ridiculously Simple, McMaster, ISBN 0940780313, p. 5