Ch. 21

Water, Electrolyte, & Basic Balance

Compare: intracellular fluid, extracellular fluid, interstitial fluid, transcellular fluid

• Intracellular Fluid

  • Found inside the cells

    • Includes all the water & electrolytes that cell membranes enclose

      • Has high concentrations of K⁺, Mg⁺², PO₄^-3, & SO₄^-2 ions

• *Extracellular fluids are all similar in composition, having high concentrations of Na⁺, Cl^-, & HCO_3- ions; low K⁺

  • Intracellular Fluid Compartment:

    • All water & electrolytes inside cell membranes

    • Contains 63% of body water

  • Transcellular Fluid: Separated from other extracellular fluids by epithelial layers; consists of: 

    • *cerebrospinal fluid

    • aqueous & vitreous humors in eye

    • synovial fluid in joints

    • serous fluid

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