Fluid & Electrolyte Q 89

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In the extracellular fluid, chloride is a major:

  

    A. Compound

    B. Ion

    C. Anion

    D. Cation

    

    

Correct Answer: C. Anion

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Chloride is a major anion found in the extracellular fluid. Chloride is an inorganic anionic halogen with an atomic weight of 35.5. It is distributed exclusively within the extracellular fluid compartment (ECF), which comprises the blood/plasma (or serum) compartment and the interstitial fluid compartment. Chloride is the major anion associated with sodium in the ECF.

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Option A: A compound occurs when two ions are bound together. When two distinct elements are chemically combined—i.e., chemical bonds form between their atoms—the result is called a chemical compound. Most elements on Earth bond with other elements to form chemical compounds, such as sodium (Na) and Chloride (Cl), which combine to form table salt (NaCl).

Option B: Chloride is an ion, but this choice is too general. Ions are formed when the number of protons in an atom does not equal the number of electrons. If more protons are present, the ion is positive and is known as a cation; if more electrons are present, the ion is negative and referred to as an anion.

Option D: HCO3 is a cation. Cations are positively charged ions. They are formed when a metal loses its electrons. They lose one or more than one electron and do not lose any protons. Therefore, they possess a net positive charge.

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