electrolyte

(ĕ-lek′trŏ-līt″)

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[electro- + -lyte]

1. A solution that conducts electricity.
2. A substance that, in solution, conducts an electric current and is decomposed by its passage. Acids, bases, and salts are common electrolytes.
3. An ionized salt in blood, tissue fluids, and cells. These salts include sodium, potassium, and chlorine. SEE TABLE: Major Electrolytes
Major Electrolytes

Electrolyte mEq/L*	Plasma Level mEq/L	ICF Level	Functions
Sodium (Na+)	136-142	10	• Creates much of the osmotic pressure of ECF; the most abundant cation in ECF
			• Essential for electrical activity of neurons and muscle cells
Potassium (K+)	3.8-5.0	141	• Creates much of the osmotic pressure in ICF; the most abundant cation in ICF
			• Essential for electrical activity of neurons and muscle cells
Calcium (Ca+2)	4.6-5.5	1	• Most (98%) is found in bones and teeth.
			• Maintains normal excitability of neurons and muscle cells
			• Essential for blood clotting
Magnesium (Mg+2)	1.3-2.1	58	• Most (50%) is found in bone
			• More abundant in ICF than in ECF
			• Essential for ATP production and activity of neurons and muscle cells
Chloride (Cl−)	95-103	4	• Most abundant anion in ECF; diffuses easily into and out of cells; helps regulate osmotic pressure
			• Part of hydrochloric acid (HCl) in gastric juice
Bicarbonate (HCO3−)	28	10	• Part of the bicarbonate buffer system
Phosphate (HPO4−2)	1.7-2.6	75	• Most (85%) is found in bones and teeth
			• Primarily an ICF anion
			• Part of DNA, RNA, ATP, phospholipids
			• Part of phosphate buffer system
Sulfate (SO4−2)	1	2	• Part of some amino acids and proteins

ELECTROLYTE CONCENTRATIONS IN BODY FLUIDS

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